Co-reporter:Hui Chen, Cheng-Bing Ma, Lei Sun, Chang-Neng Chen
Polyhedron 2017 Volume 132(Volume 132) pp:
Publication Date(Web):16 August 2017
DOI:10.1016/j.poly.2017.04.023
A family of octanuclear clusters [FeIII4LnIII4O2(OH)4(mosaoH)4 (Piv)4(N-mdea)4(H2O)2] [Ln = Y(1), Gd(2), Tb(3) and Dy(4), mosaoH2 = 3-Methyloxysalicylaldoxime, N-mdeaH2 = N-methyl diethanolamine, pivH = pivalic acid] has been prepared by reactions of [Fe3O(piv)6(OH2)2(OH)]·H2O with Ln(NO3)3·6H2O, mosaoH2 and N-mdeaH2 ligands. The crystal structures of 1–4 were obtained, and their core can be described as two distorted tetrahedral subunits of [Fe2Ln2(μ4–O)] connected by a pair of μ3–OH− groups. A dc magnetic susceptibility study reveals that there exist strong antiferromagnetic interactions between the neibouring Fe atoms. Fitting of the susceptibility data of compound 1 containing diamagnetic YIII ions gives J = −127 cm−1. Compound 4 exhibits frequency-dependent out-of-phase ac susceptibility signals indicative of slow magnetization relaxation.A family of FeIII4LnIII4 clusters containing 3-methyloxysalicylaldoximate ligand has been prepared, and their crystal structures and magnetic properties have been studied. Among them, compound FeIII4DyIII4 exhibits frequency-dependent out-of-phase ac susceptibility signals indicative of slow magnetization relaxation.Download high-res image (127KB)Download full-size image
Co-reporter:Lei Sun, Hui Chen, Chengbing Ma and Changneng Chen
RSC Advances 2016 vol. 6(Issue 15) pp:12408-12413
Publication Date(Web):25 Jan 2016
DOI:10.1039/C5RA25526K
Reactions of manganese nitrate and lanthanide nitrate hexahydrate with 2-(hydroxymethyl)pyridine (hmpH) and sodium propionate as co-ligands in the mixed solutions of acetonitrile and ethanol generated two hexanuclear Mn–Ln compounds [Mn4Ln2O2(OH)(hmp)5(EtCO2)3(MeCN)(NO3)5(H2O)] [Ln = La (1), Nd (2)]. Compounds 1 and 2 are isostructural and possess a core of [MnIII4LnIII2(μ3-OR)3(μ3-O)2(μ2-O)3]5+, which comprises three face-sharing defect cubane units. The core topology represents a new core type of Mn–Ln cluster. The soild-state dc magnetic susceptibility analyses indicate antiferromagnetic interactions within the two compounds. Compound 1 possesses an S = 0 ground state spin, fitting of the dc data for a tetranuclear MnIII4 with the Magpack program gives parameters of J1 = −0.50 cm−1, J2 = −5.03 cm−1, J3 = 3.77 cm−1 and g = 1.95.
Co-reporter:Lei Sun, Hui Chen, Chengbing Ma and Changneng Chen
Dalton Transactions 2015 vol. 44(Issue 48) pp:20964-20971
Publication Date(Web):06 Nov 2015
DOI:10.1039/C5DT03130C
A new family of isostructural Mn/Ln dodenuclear clusters: [Mn8Ln4(O)8(hmp)4(O2CPh)12(NO3)4(PhCO2H)(C2H5OH)] [Ln = La (1), Pr (2), Nd (3), Gd (4), Dy(5), hmpH = 2-(hydroxymethyl)pyridine] have been synthesized by the reaction of Mn(NO3)2 and Ln(NO3)3·6H2O with hmpH and benzoic acid as co-ligands. Compounds 1–5 possess a spindle-shaped core of [MnIII8LnIII4(μ4-O)4(μ3-O)4(μ3-OR)2(μ2-OR)8]10+, which is composed of six face-sharing defected cubane units and two square-pyramidal units. The compounds represent the highest nuclearity Mn/Ln clusters with the use of hmpH to date. That the ferromagnetic interactions dominated within complexes 1–4 were suggested by solid-state dc magnetic susceptibility analyses. Compound 4 displays a magnetic-caloric effect (MCE) with 13.94 J kg−1 K−1 as the entropy change at 6 K for ΔH = 8 T. Compounds 1 and 5 exhibit an out-of-phase χ′′M peak maximum above 2.0 K. Fitting of the ac susceptibility data to an Arrhenius law gives an energy barrier Ueff = 6.88/7.44 K for compounds 1 and 5 respectively.
Co-reporter:Jin-ying Liu, Cheng-bing Ma, Hui Chen and Chang-neng Chen
CrystEngComm 2015 vol. 17(Issue 45) pp:8736-8745
Publication Date(Web):15 Oct 2015
DOI:10.1039/C5CE01471A
Four novel manganese phosphonate clusters, namely Cl@[Mn6(t-BuPO3)8(H2O)2(CH3OH)4][OH] (1), Br@[Mn6(t-BuPO3)8(H2O)2(CH3OH)4][OH]·4H2O (2), [Mn13O6(t-BuPO3)10(OH)6(CH3OH)6][Mn13O6(t-BuPO3)10(OCH3)6(t-BuPO3H2)2(H2O)4]·2CH3OH·10H2O (3) and [Mn15K2O8(t-BuPO3)10(CH3O)4(C6H5COO)4(H2O)8]·6H2O (4), have been successfully synthesized in the presence of tert-butylphosphonic acid, carboxylic acid, NBun4MnO4 and different manganese sources. These clusters were characterized by elemental analyses, IR spectroscopy, thermogravimetric (TG) analyses and single-crystal X-ray diffraction. Single-crystal structure analyses reveal that the structures of 1–4 are diverse. The structure of cluster 1 is analogous to that of cluster 2, which displays a cage-like arrangement with one halide ion (Cl−, Br−) lying inside the centre of the cave. Cluster 3 is a carboxylate-free manganese phosphonate cluster consisting of two similar Mn13 structural units. Moreover, there exist two potassium ions and fifteen manganese ions in the heterometallic cluster 4. In addition, solid-state DC magnetic susceptibility measurements indicate the existence of overall antiferromagnetic (AF) exchange interactions between the Mn ions in all clusters.
Co-reporter:Xiaowei Song, Huimin Wen, Chengbing Ma, Hui Chen and Changneng Chen
New Journal of Chemistry 2015 vol. 39(Issue 3) pp:1734-1741
Publication Date(Web):15 Dec 2014
DOI:10.1039/C4NJ01858C
A pentadentate aminopyridine ligand [(9-methyl-1,10-phenanthrolin-2-yl)methyl]bis-(pyridin-2-ylmethyl)amine (DPA-Dmphen) has been prepared and characterized. This ligand readily accommodates Co(II) or Ni(II) bearing a coordinated apical water ligand, and the resulting complexes of general formula [M(Dmphen-DPA)(H2O)](ClO4)2 (MCo (1) and MNi (2)) have been investigated for photo- and electrocatalytic proton reduction in CH3CN–H2O (1/3, v/v) mixed solvent and CH3CN, respectively. Under visible-light irradiation (λ > 400 nm), complex 1 shows hydrogen evolution activity in the presence of [Ir(ppy)2(bpy)]PF6 as a photosensitizer and TEA as an electron donor, whereas 2 displays much lower catalytic activity under the same conditions. The highest turnover number (TON) of 210 is achieved for H2 evolution from an optimized system containing 1 (0.1 mM), [Ir(ppy)2(bpy)](PF6) (0.5 mM), and 10 vol% TEA in CH3CN–H2O (1/3, v/v) mixed solvents at pH 10. Under those conditions catalytic hydrogen production is mainly limited by photosensitizer and catalyst stability. Furthermore, electrochemical studies reveal that both complexes are active for electrocatalytic proton reduction in acetonitrile, when using acetic acid as a proton source with overpotentials of (0.48 V vs. Fc+/Fc) for 1 and (0.46 V vs. Fc+/Fc) for 2.
Co-reporter:Hui Chen, Cheng-Bing Ma, Ming-Qiang Hu, Hui-Min Wen and Chang-Neng Chen
Dalton Transactions 2014 vol. 43(Issue 44) pp:16737-16744
Publication Date(Web):15 Sep 2014
DOI:10.1039/C4DT01816H
Using 3-methyloxysalicylaldoxime (mosaoH2) and N-methyl diethanolamine (N-mdeaH2) as coligands, a family of heptanuclear Mn/Ln heterometallic compounds [MnIIMnIII2LnIII4(mosao)2(mosaoH)4(piv)4(N-mdea)4]·xMeCN [Ln = Dy(1), Tb(2) and Y(3), pivH = pivalic acid] have been prepared. The crystal structures of 1–3 were obtained, and their core consists of two MnIIILn2(μ3-OR)2 (RO2− = N-mdea2−) triangles linked to a central MnII atom. A dc magnetic susceptibility study reveals that single-ion effects of the Ln ions are dominant in compounds 1 and 2. As for compound 3, which contains diamagnetic Y ions, the magnetic interactions between Mn ions via oximate NO bridges are revealed to be ferromagnetic. Fitting of the χmT vs. T data gives g = 1.96 and J = 1.12 cm−1, affording a S = 13/2 ground state. All of the three compounds exhibit frequency-dependent out-of-phase ac susceptibility signals indicative of slow magnetization relaxation and potential SMM behavior. Among them, 1 and 3 display the out-of-phase χ′′m peak maximum above 2.0 K. Fitting of the ac susceptibility data to the Arrhenius law gives an energy barrier Ueff = 9.27/13.83 K for 1 and 3, respectively.
Co-reporter:Xiao-Wei Song, Hui-Min Wen, Cheng-Bing Ma, Hong-Hua Cui, Hui Chen and Chang-Neng Chen
RSC Advances 2014 vol. 4(Issue 36) pp:18853-18861
Publication Date(Web):11 Apr 2014
DOI:10.1039/C4RA01413H
Three comparable hybrid photocatalytic systems, comprising semiconductor g-C3N4, end-group-functionalized cobaloxime complexes (carboxy-functionalized cobaloxime, C1; pyrene-functionalized cobaloxime, C2; and non-functionalized cobaloxime, C3), and triethanolamine (TEOA), are active for visible-light-driven hydrogen production in CH3CN–H2O (9/1, v/v) solution. Upon irradiation for 12 h, the turnover numbers of hydrogen evolution are 234, 281 and 195 for the hybrid systems C1/g-C3N4, C2/g-C3N4 and C3/g-C3N4, respectively. The highest hydrogen evolution efficiency of the C2/g-C3N4 system can be attributed to the strongest π–π interactions between the pyrene moiety and g-C3N4. Based on electrochemical properties, steady-state photoluminescence spectra and theoretical analyses, the visible light absorption of g-C3N4, the catalytic H2-evolving ability of cobaloxime as well as the efficient charge separation of the excited g-C3N4 in the presence of both TEOA and cobaloxime, are responsible for the high activity of these hybrid systems.
Co-reporter:Ying-Qi Xu;Jian Luo ;Zhong-Ning Chen
European Journal of Inorganic Chemistry 2014 Volume 2014( Issue 20) pp:3208-3215
Publication Date(Web):
DOI:10.1002/ejic.201402197
Abstract
The gadolinium(III) complexes GdL1 and GdL2 were designed as Zn2+-responsive bimodal magnetic resonance imaging (MRI) and fluorescence imaging probes. Upon binding to Zn2+ ions, GdL1 exhibits a bidentate or tridentate mode to form heterodinuclear GdL1Zn or heterotrinuclear (GdL1)2Zn, whereas GdL2 binds to the Zn2+ ion only in a bidentate mode to form (GdL2)2Zn. The gadolinium(III) complexes derived from both H3L1 and H3L2 exhibit remarkable interactions with human serum albumin (HSA) at both site I and site II, which result in significant enhancements of the relaxivity and remarkable improvements of T1-weighted imaging contrast. In the presence of HSA, both the relaxivity (r1) and fluorescence exhibit 300 % enhancement with a clear blueshift of the fluorescence for GdL1Zn, which is ascribed to direct binding to HSA through the formation of a Zn–HSA coordination bond. In contrast, the presence of HSA induces smaller relaxivity increases for GdL1 (155 %), (GdL1)2Zn (183 %), GdL2 (192 %), and (GdL2)2Zn (181 %); these increases are ascribed to weaker hydrophobic interactions or stereospecificity with HSA. The contrast of T1-weighted phantom MR images of these gadolinium(III) complexes in human serum (HS) is much improved relative to that in 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES) buffer solutions.
Co-reporter:Xiao-Wei Song;Hui-Min Wen;Cheng-Bing Ma;Ming-Qiang Hu;Hui Chen;Hong-Hua Cui
Applied Organometallic Chemistry 2014 Volume 28( Issue 4) pp:267-273
Publication Date(Web):
DOI:10.1002/aoc.3119
Two photocatalytic hydrogen evolution systems were constructed by assembling [FeFe]-hydrogenase mimics, either carboxyl group-containing (C1) or not (C2), on to the surface of ZnS using triethanolamine as electron donor in DMF-H2O (9/1, v/v) solution. Upon irradiation for 30 h, the turnover numbers of hydrogen evolution were 3400 and 4950 for the hybrid system C1/ZnS and C2/ZnS, respectively. The photocatalytic activity of the C2/ZnS system was five times higher than the activity of the pristine ZnS, suggesting that the [FeFe]-hydrogenase mimics are crucial toward improving the activity of ZnS. On the basis of the spectroscopic studies and analyses, the photogenerated electron transfer from ZnS to the mimics is probably responsible for the activity enhancement of ZnS. The time dependence of hydrogen generation shows that the mimic C2 is more active than C1. The different hydrogen evolution activity can be attributed to the different adsorption modes of the two [FeFe]-hydrogenase mimics on the surface of ZnS. Copyright © 2014 John Wiley & Sons, Ltd.
Co-reporter:Hong-Hua Cui, Nan-Nan Wu, Jin-Yun Wang, Ming-Qiang Hu, Hui-Min Wen, Chang-Neng Chen
Journal of Organometallic Chemistry 2014 Volume 767() pp:46-53
Publication Date(Web):15 September 2014
DOI:10.1016/j.jorganchem.2014.04.026
•Pyrimidyl-diphosphine substituted [Fe2S2] mimics have been firstly synthesized.•Complexes 3, 5 and 6 exhibit two reduction waves, while 2 and 4 show only one.•PNNP makes the contributions to LUMO of 3 not only from diiron units but also PNNP.Two tetranuclear iron–sulphur complexes {[(μ-pdt)Fe2(CO)5]2(PNP) (2) and [(μ-pdt)Fe2(CO)5]2(PNNP) (3)} and three dinuclear ones {[(μ-pdt)Fe2(CO)5](PNP) (4), [(μ-pdt)Fe2(CO)5](PNNP) (5) and [(μ-pdt)Fe2(CO)5](PNN) (6)} were synthesized, using two new pyrimidyl-phosphine ligands PNNP [4,6-bis(diphenylphosphino) pyrimidine] and PNN (4-tertiary butyl-6-diphenylphosphino pyrimidine) together with the reported pyridyl-phosphine PNP [bis(diphenylphosphino)pyridine] as substituents to react with Fe2(μ-pdt)(CO)6. The molecular structures of 2, 3 and 6 were confirmed by single-crystal X-ray analyses, which show that all phosphine ligands occupy the apical positions, while the space group of 3 (P21/n) is different from that of 2 (P-1). Cyclic voltammograms reveal that pyrimidyl-phosphine substituted complexes 3, 5 and 6 present two reduction waves in CH2Cl2 solutions, while pyridyl-phosphine substituted 2 and 4 show only one. The DFT computational studies demonstrate that the contributions to the LUMO of 3 are comparable from the two Fe2S2 centres and ligated PNNP ligand, which is different from those of other [Fe2S2] mimics in this work.The contributions to the LUMO of 3 are comparable from the two [Fe2S2] centres and the ligated PNNP, which is different from other [Fe2S2] mimics, such as complex 2.
Co-reporter:Xiaowei Song, Huimin Wen, Chengbing Ma, Changneng Chen
Polyhedron 2014 Volume 81() pp:639-645
Publication Date(Web):15 October 2014
DOI:10.1016/j.poly.2014.07.031
A cobalt complex based on the tripodal iminopyridine type ligand (2E)-2-N-(pyridin-2-ylmethylidene)-1-N,1-N-bis({2-[(E)-(pyridin-2-ylmethylidene)amino]phenyl})benzene-1,2-diamine (L1), namely, [CoL1](BF4)2 (1a), was synthesized and characterized by FT-IR, UV–Vis spectroscopy, magnetic moment and elemental analysis. X-ray structural study of 1a shows that the complex is coordinatively saturated and contains the uncoordinated bridgehead nitrogen atom. Electrochemical studies reveal that the complex 1a has an electrocatalytic proton reduction activity in acetonitrile, when using acetic acid as a proton source with icat/ip ∼ 3.3. Therefore we estimate that the complex 1a could give the highest TOF of 2.3 s−1 for the reduction of proton to hydrogen. Furthermore, under visible-light irradiation, an optimized H2 evolution system containing 1a (0.1 mM), [Ir(ppy)2(bpy)](PF6) (0.1 mM), and 10 vol% TEA in CH3CN–H2O (1/1, v/v) mixed solvents at pH 10 gives a highest turnover number of 34. For comparison, an electron-withdrawing ester group (CO2CH2CH3) is introduced into the pyridine moiety of the ligand as in L2, however, which leads to its corresponding cobalt complex 2a less active than the complex 1a for electro- and photocatalytic H2 evolution. Additionally, the control experiment establishes that the isostructural zinc complex [ZnL1](BF4)2 (1b) is ineffective for H2 generation.Graphical abstractA cobalt complex 1a of tripodal iminopyridine type ligand was synthesized and characterized. The complex is capable of electro-catalyzing proton reduction in acetonitrile using acetic acid as a proton source and photo-catalyzing hydrogen generation in combination with the photosensitizer [Ir(ppy)2(bpy)]PF6.
Co-reporter:Hong-hua Cui, Jin-yun Wang, Ming-qiang Hu, Cheng-bing Ma, Hui-min Wen, Xiao-wei Song and Chang-neng Chen
Dalton Transactions 2013 vol. 42(Issue 24) pp:8684-8691
Publication Date(Web):21 Mar 2013
DOI:10.1039/C3DT50140J
Exploration of the complex Ni2(MBD)4 (MBD = 2-mercaptobenzimidazole) (C1) having different coordinated Ni atoms as a photocatalyst for hydrogen evolution is made. For comparison, the bimetallic Ni2(MBT)4 (MBT = 2-mercaptobenthiazole) (C2) complex with the same coordinated Ni atoms was synthesized. Both of the complexes have been successfully constructed for photo-induced hydrogen production using organic dyes as photosensitizers and triethanolamine (TEOA) as the effective electron donor by visible light (>400 nm) in acetonitrile–water solution. The time-dependence of H2 generation and DFT computational studies demonstrate that the complex C1 is more active than C2 for H2 evolution. The mechanisms of photocatalytic hydrogen generation for C1 and C2 involve different protonation sites resulting from the differences between the two structures.
Co-reporter:Hui Chen, Cheng-Bing Ma, Ming-Qiang Hu, Hui-Min Wen, Hong-Hua Cui, Jin-Ying Liu, Xiao-Wei Song and Chang-Neng Chen
Dalton Transactions 2013 vol. 42(Issue 14) pp:4908-4914
Publication Date(Web):07 Jan 2013
DOI:10.1039/C2DT32739B
Reactions of [Mn6O2(piv)10(py)2.5(piv)1.5], Ln(NO3)3·6H2O and N-mdeaH2 in MeCN in the presence of Me3SiCl generated a family of octanuclear Mn/Ln complexes [Mn6IIIMnIILn(N-mdea)3(N-mdeaH)(piv)8O2(OH)3(NO3)(H2O)]·xCH3CN·xH2O [Ln = Gd (1), Dy (2), Er (3), pivH = pivalic acid, N-mdeaH2 = N-methyl diethanolamine]. Each complex possesses a [Mn6IIIMnIILn(μ3-O)2(μ3-OH)3]16+ core containing two butterfly-like subunits of [Mn3Ln(μ3-OH)2] and [Mn4(μ3-O)2] sharing a common vertex, and an outer Mn atom ligated to one of the subunits through a μ3-OH− ligand. The core topology represents a new Mn/Ln core type. The magnetic susceptibility study of 1–3 indicates the presence of dominant antiferromagnetic interactions within the complexes. For complex 1, which contains an isotropic GdIII atom, fitting of the obtained M/(NμB) vs. H/T data gave S = 4, g = 1.90, and D = −0.31 cm−1. The results were further supported by ac data. Complex 3 exhibits out-of-phase ac susceptibility signals, indicating it may be a SMM.
Co-reporter:Jinying Liu, Chengbing Ma, Hui Chen, Mingqiang Hu, Huimin Wen, Honghua Cui and Changneng Chen
Dalton Transactions 2013 vol. 42(Issue 11) pp:3787-3790
Publication Date(Web):07 Feb 2013
DOI:10.1039/C3DT32985B
A family of heptanuclear [MnII3LnIII4] clusters with planar disc-like cores have been synthesized by a solvothermal route, where Ln = La, Pr, Nd, and Gd, and such fascinating topology is unprecedented in 3d–4f complexes. Dc magnetic susceptibility data show different magnetic behaviors derived from the difference in Ln ions.
Co-reporter:Jinying Liu, Chengbing Ma, Hui Chen, Mingqiang Hu, Huimin Wen, Honghua Cui, Xiaowei Song and Changneng Chen
Dalton Transactions 2013 vol. 42(Issue 7) pp:2423-2430
Publication Date(Web):12 Nov 2012
DOI:10.1039/C2DT32269B
A new family of isostructural Mn–Ln heterometallic clusters, [MnII2MnIII2LnIII2(Piv)8(thme)2(H2tea)2] (H3thme = 1,1,1-tris(hydroxymethyl)ethane, Hpiv = pivalic acid, H3tea = triethanolamine, and Ln = Pr, Nd, Sm, Eu, Gd, Tb, and Dy) have been prepared by reaction of the hexanuclear manganese precursor, [Mn6O2(Piv)10(4-Me-Py)2.5(Hpiv)1.5], with H3thme, H3tea, and Ln(NO3)3·6H2O under the solvothermal conditions. Complexes 1Pr–7Dy were characterized by single-crystal X-ray diffraction and their core [Mn2IIIMn2IILn2III(μ3-OR)4(μ2-OR)6]6+ composed of four face-sharing defected cubane units. Antiferromagnetic (AF) exchange interactions were suggested for all of the complexes by solid-state dc magnetic susceptibility measurements. Complexes 6Tb and 7Dy, show frequency-dependent ac susceptibility signals suggestive of slow magnetic relaxation.
Co-reporter:Hu-Min Wen;Jin-Yun Wang;Bin Li;Li-Yi Zhang, ;Zhong-Ning Chen
European Journal of Inorganic Chemistry 2013 Volume 2013( Issue 27) pp:4789-4798
Publication Date(Web):
DOI:10.1002/ejic.201300622
Abstract
A series of platinum(II) complexes bearing 1,3-bis(2-pyridylimino)isoindoline (BPI) derivatives as ligand have been prepared by substitution of the coordinated Cl in precursors [Pt(L)Cl] [L = L1 (1), L2 (2), L3 (3)] by a monodentate strong-field ligand such as CN–, CN-cyclohexyl, PPh3, NCS–, PhS–, or N(CN)2–. Most of these compounds display orange-to-red luminescence in both the solid state and solution at ambient temperature. Compared with precursors 1–3, both low-energy absorption and emission bands in ligand-substituted platinum(II) complexes 4–13 exhibit distinct blueshifts. The emission of platinum(II) complexes with CN-containing monodentate ligands shows progressive blueshifts with increasing ligand field strength: 609 (10, NCS–) 603 [12, N(CN)2–] 590 (4, CN–) 581 nm (7, C≡N-cyclohexyl). The emission of complexes 4–9 originates mainly from the 3[π π*(BPI)] 3IL triplet excited state, mixed with some 3[dπ(Pt) π*(BPI)] 3MLCT character. In contrast, the emission of 10–13 arises from a clearly increased 3[π(L) π*(BPI)] 3LLCT state with reduced 3[π π*(BPI)] 3IL and 3[5d(Pt) π*(BPI)] 3MLCT character. Noticeably, dicyanamido-linked dinuclear complex 13 displays a significant ligand–ligand electronic interaction between the two BPI across the Pt–N≡C–N–C≡N–Pt bridge with remarkable LLCT character from one BPI to the other.
Co-reporter:Hong-hua Cui, Ming-qiang Hu, Hui-min Wen, Guo-liang Chai, Cheng-bing Ma, Hui Chen and Chang-neng Chen
Dalton Transactions 2012 vol. 41(Issue 45) pp:13899-13907
Publication Date(Web):06 Sep 2012
DOI:10.1039/C2DT31618H
Two [FeFe] hydrogenase mimics, [Fe2(μ-pdt)(CO)5L1] (L1 = PPh2SPhNH2) (Ph = phenyl) (2) and [Fe2(μ-pdt)(CO)5L2] (L2 = PPh2PhNH2) (3), and two molecular photocatalysts, [(CO)5(μ-pdt)Fe2PPh2SPhNHCO(bpy)(ppy)2Ir]PF6 (bpy = bipyridine, ppy = 2-phenylpyridine) (2a) and [(CO)5(μ-pdt)Fe2PPh2PhNHCO(bpy)(ppy)2Ir](PF6) (3a), have been designed and synthesized, anchoring Ir(ppy)2(mbpy)PF6 (mbpy = 4-methyl-4′-carbonyl-2,2′-bipyridine) (PS) to one of the iron centers of complexes 2 and 3 by forming amide bonds. Molecular dyads 2a, 3a and the intermolecular systems 2, 3 with PS have also been successfully constructed for photoinduced H2 production using triethylamine (TEA) as a sacrificial electron donor by visible light (>400 nm) in CH3CN–H2O solution. The time-dependence of H2 generation and spectroscopic studies suggest that the activity of H2 evolution can be tuned by addition of a S atom to the phosphane ligand. The highest turnover numbers (TON) of hydrogen evolution obtained are 127, using 2a as a photocatalyst in a supramolecular system, and 138, based on catalyst 2 in a multi-component system. Density functional theory (DFT) computational studies demonstrate that the S atom in the second coordination sphere makes complex 2 accept an electron more easily than 3 and improves the activity in light-induced hydrogen production.
Co-reporter:Hui-Min Wen, Jin-Yun Wang, Ming-Qiang Hu, Bin Li, Zhong-Ning Chen and Chang-Neng Chen
Dalton Transactions 2012 vol. 41(Issue 38) pp:11813-11819
Publication Date(Web):03 Aug 2012
DOI:10.1039/C2DT31507F
A diiron dithiolate complex 1o with a dithienylethene (DTE) phosphine ligand has been elaborately designed and fully investigated by spectroscopic and DFT computational studies. Upon irradiation with UV light, the DTE moiety in complex 1o undergoes an excellent photocyclization reaction to attain ring-closed state 1c in high yield (>95%), accompanied by a colour change from orange to deep blue. On the other hand, upon irradiation with visible light (>460 nm), ring-closed form 1c in CH3CN solution reverts perfectly into ring-open form 1o. Both 1o and 1c were characterised by IR, 1H, 31P, 19F NMR and electrochemical spectroscopy. The electrochemical behaviours of both the open and closed forms were investigated by cyclic voltammetry. Upon photocyclization reaction, a 290 mV (from −2.29 V to −2.00 V) positive shift is induced in the potential of electrochemical catalytic proton reduction, due to the electron-withdrawing effect of the ring-closed DTE moiety. Consequently, complex 1 can reversibly photoswitch the potential of proton reduction on the [FeFe] moiety.
Co-reporter:Hui Chen, Cheng-Bing Ma, Da-Qiang Yuan, Ming-Qiang Hu, Hui-Min Wen, Qiu-Tian Liu, and Chang-Neng Chen
Inorganic Chemistry 2011 Volume 50(Issue 20) pp:10342-10352
Publication Date(Web):September 16, 2011
DOI:10.1021/ic201403k
A family of MnIII/NiII heterometallic clusters, [MnIII4NiII5(OH)4(hmcH)4(pao)8Cl2]·5DMF (1·5DMF), [MnIII3NiII6(N3)2(pao)10(hmcH)2(OH)4]Br·2MeOH·9H2O (2·2MeOH·9H2O), [MnIIINiII5(N3)4(pao)6(paoH)2(OH)2](ClO4)·MeOH·3H2O (3·MeOH·3H2O), and [MnIII2NiII2(hmcH)2(pao)4(OMe)2(MeOH)2]·2H2O·6MeOH (4·2H2O·6MeOH) [paoH = pyridine-2-aldoxime, hmcH3 = 2, 6-Bis(hydroxymethyl)-p-cresol], has been prepared by reactions of Mn(II) salts with [Ni(paoH)2Cl2], hmcH3, and NEt3 in the presence or absence of NaN3 and characterized. Complex 1 has a MnIII4NiII5 topology which can be described as two corner-sharing [Mn2Ni2O2] butterfly units bridged to an outer Mn atom and a Ni atom through alkoxide groups. Complex 2 has a MnIII3NiII6 topology that is similar to that of 1 but with two corner-sharing [Mn2Ni2O2] units of 1 replaced with [Mn3NiO2] and [MnNi3O2] units as well as the outer Mn atom of 1 substituted by a Ni atom. 1 and 2 represent the largest 3d heterometal/oxime clusters and the biggest MnIIINiII clusters discovered to date. Complex 3 possesses a [MnNi5(μ-N3)2(μ-OH)2]9+ core, whose topology is observed for the first time in a discrete molecule. Careful examination of the structures of 1–3 indicates that the Mn/Ni ratios of the complexes are likely associated with the presence of the different coligands hmcH2– and/or N3–. Complex 4 has a MnIII2NiII2 defective double-cubane topology. Variable-temperature, solid-state dc and ac magnetization studies were carried out on complexes 1–4. Fitting of the obtained M/(NμB) vs H/T data gave S = 5, g = 1.94, and D = −0.38 cm–1 for 1 and S = 3, g = 2.05, and D = −0.86 cm–1 for 3. The ground state for 2 was determined from ac data, which indicated an S = 5 ground state. For 4, the pairwise exchange interactions were determined by fitting the susceptibility data vs T based on a 3-J model. Complex 1 exhibits out-of-phase ac susceptibility signals, indicating it may be a SMM.
Co-reporter:Cheng-Bing Ma;Ming-Qiang Hu;Hui Chen, ;Qiu-Tian Liu
European Journal of Inorganic Chemistry 2011 Volume 2011( Issue 32) pp:5043-5053
Publication Date(Web):
DOI:10.1002/ejic.201100719
Abstract
A series of homo- and heterometallic manganese(III or IV) clusters, [Mn2O2(pybim)4](NO3)4·11H2O [1; pybim = 2-(2-pyridyl)benzimidazole], [Mn3O4(bipy)4(H2O)2][Ce(NO3)5(H2O)][NO3]2·2H2O (2; bipy = 2,2′-bipyridine), [Mn2Ce3O6(pta)6(NO3)2(dmf)4]·H2O (3; Hpta = p-toluic acid), and [Mn8CeO8(pta)12(dmf)4] (4), were prepared by the reaction of simple Mn2+ salts with (NH4)2[Ce(NO3)6] under different experimental conditions. The single-crystal X-ray diffraction analyses established that these complexes possess inorganic cores that have various structural topologies, which range from the [Mn2O2]4+ rhomb, a Mn3 triangle within [Mn3O4]4+, and the nonplanar [Mn8O8]8+ loop that centrally traps a Ce4+ ion to the [Mn2Ce3O6]8+ cage that contains a Mn2Ce3 trigonal bipyramid. The solid-state magnetic susceptibility studies revealed that these four complexes possess distinctly different magnetic properties, namely, both 1 and 2 show strong antiferromagnetic interactions between the MnIV centers, whereas 3 is weakly antiferromagnetic, and 4, however, has predominantly ferromagnetic interactions.
Co-reporter:Hui-Min Wen ; Yu-Hui Wu ; Yang Fan ; Li-Yi Zhang ; Chang-Neng Chen ;Zhong-Ning Chen
Inorganic Chemistry 2010 Volume 49(Issue 5) pp:2210-2221
Publication Date(Web):January 27, 2010
DOI:10.1021/ic902019s
Reactions of 1,3-bis(2-pyridylimino)isoindoline (HL1), 1,3-bis(2-pyridylimino)benz(f)isoindoline (HL2), or 5,6-dihydro-2,3-diphenyl-5-(pyridin-2-ylimino)pyrrolo[3,4-b]pyrazin-7-ylidene)pyridin-2-amine (HL3) with Pt(tht)2Cl2 (tht = tetrahydrothiophene) afforded the corresponding Pt(L)Cl complexes. A series of neutral platinum(II) alkynyl complexes Pt(L)(C≡CR) were prepared by reactions of the precursors Pt(L)Cl with alkynyl ligands through CuI-catalyzed platinum acetylide σ coordination. Crystal structural determination of Pt(L3)Cl (3), Pt(L1)(C≡CPh) (4), and Pt(L1)(C≡CC6H4But-4) (6) by X-ray crystallography revealed that the neutral platinum(Π) complexes with monoanionic tridentate L ligands display more perfect square-planar geometry than that in platinum(II) complexes with neutral tridentate 2,2′:6′,2′′-terpyridyl ligands. Both the Pt(L)Cl and Pt(L)(C≡CC6H4R-4) complexes exhibit low-energy absorption at 400−550 nm, arising primarily from π → π*(L) intraligand (IL) and 5d(Pt) → π*(L) metal-to-ligand charge-transfer (MLCT) transitions as suggested from density functional theory calculations. They display bright-orange to red room-temperature luminescence in fluid dichloromethane solutions with microsecond to submicrosecond ranges of emissive lifetimes and 0.03−3.79% quantum yields, originating mainly from 3IL and 3MLCT excited states. Compared with the emissive state in Pt(L)Cl complexes, substitution of the coordinated Cl with C≡CC6H4R-4 in Pt(L)(C≡CC6H4R-4) complexes induces an obviously enhanced contribution from the 3[π(C≡CC6H4R-4) → π*(L)] ligand-to-ligand charge-transfer (LLCT) triplet state. The photophysical properties can be finely tuned by modifying both the L and alkynyl ligands. The calculated absorption and emission spectra in dichloromethane coincide well with those measured in a fluid dichloromethane solution at ambient temperature.
Co-reporter:Ming-Qiang Hu, Hui-min Wen, Cheng-Bing Ma, Na Li, Qing-Yun Yan, Hui Chen and Chang-Neng Chen
Dalton Transactions 2010 vol. 39(Issue 40) pp:9484-9486
Publication Date(Web):08 Sep 2010
DOI:10.1039/C0DT00505C
A series of model complexes [(μ-pdt)Fe2(CO)5]2M(sip)2 (M = Fe, Ni) were synthesized as H-cluster analogues of [FeFe]-hydrogenase. Their electrochemical behaviours were investigated and it is proposed that the bridging metal bis(tris-chelate) groups act as electron transfer sites in theses mimics.
Co-reporter:Mei Wang, Da-Qiang Yuan, Cheng-Bing Ma, Ming-Jian Yuan, Ming-Qiang Hu, Na Li, Hui Chen, Chang-Neng Chen and Qiu-Tian Liu
Dalton Transactions 2010 vol. 39(Issue 31) pp:7276-7285
Publication Date(Web):28 Jun 2010
DOI:10.1039/C002474K
The use of phosphonic acids in the synthesis of mixed-metal CeMn complexes has led to the formation of two phosphonate complexes with unusual topologies: [Ce2Mn6O6(OH)5(t-BuPO3)6(O2CMe)3]·53H2O (1·53H2O) and [Ce22Mn12O34(MePO3)12(O2CMe)33(OMe)6(NO3)(H2O)12]n (2). The two mixed-metal CeMn complexes were both prepared from a reaction system containing Mn(O2CMe)2 and (NH4)2[Ce(NO3)6] with similar procedures except for using different phosphonic acids (tert-butylphosphonic acid and methylphosphonic acid, respectively) as coligands. Both complexes possess rare topology of triangular type, with compound 1 being a 0D discrete cluster, whereas, compound 2 is a 1D polymer. The octanuclear core of complex 1 is composed of three symmetry equivalent distorted cubanes {CeIV2MnIV2O2(OH)2} sharing a trigonal-bipyramidal unit {CeIV2(OH)3} in the centre. Compound 2 is a one-dimensional chain polymer of identical Ce22Mn12O34 units linked together by NO3− and MeCO2− groups, while the Ce22Mn12O34 unit is constituted by two centrosymmetric Ce9IVCe2IIIMnIV6O17 subunits, which features three identical distorted cubanes {CeIV2MnIV2O4} connecting to a central trigonal-bipyramidal unit {CeIV3O2}, and two additional CeIII ions capping the top and bottom of the central trigonal bipyramid by six MePO32− ligands. Complexes 1 and 2 are the first high-nuclearity Mn/Ln aggregates reported to date using phosphonates as ligands. Magnetic susceptibility measurements reveal that compound 1 displays dominant ferromagnetic interactions between the adjacent metal ions with the best fit parameters for the exchanges are J1 = 6.186 cm−1, J2 = 4.172 cm−1, and with a result of S = 9 ground state confirmed by the M versus HT−1 data, which indicates the spins of all the six MnIV ions in the cluster are parallel to each other. In contrast, the data for 2 reveals overall antiferromagnetic couplings within the cluster and a resulting S = 6 ground state. Both the in-phase signal χ′MT and out-of-phase signal χ′′M of the two complexes exhibit frequency-dependent below approximate 3 K.
Co-reporter:Cheng-Bing Ma, Ming-Qiang Hu, Hui Chen, Mei Wang, Chun-Xia Zhang, Chang-Neng Chen and Qiu-Tian Liu
CrystEngComm 2010 vol. 12(Issue 5) pp:1467-1473
Publication Date(Web):04 Jan 2010
DOI:10.1039/B921483F
A new isophthalate manganese(II) coordination polymer, [Mn3(ip)3(bipy)2]n·2nH2O (1) (H2ip = isophthalic acid and bipy = 2,2′-bipyridine), with a 2D layer structure built up from isophthalato-linking trimanganese clusters, is obtained by refluxing a weakly basic solution containing bipy, Mn(OAc)2·4H2O, H2ip, and triethylamine. Both the complex and the dehydrated materials show irreversible water adsorption at room temperature, accompanied by facile single-crystal-to-single-crystal structural transformation forming a 1D chain-like coordination polymer upon rehydration, [Mn(ip)(bipy)(H2O)2]n·nH2O (2). The thermogravimetric behavior and magnetic properties of both the complexes are examined.
Co-reporter:Na Li, Mei Wang, Cheng-Bing Ma, Ming-Qiang Hu, Rong-Wei Zhou, Hui Chen, Chang-Neng Chen
Inorganic Chemistry Communications 2010 Volume 13(Issue 6) pp:730-732
Publication Date(Web):June 2010
DOI:10.1016/j.inoche.2010.03.031
A new tri-metallic Mn/Ca/Na coordination polymer, {[Mn3NaCa(sal)6(H2O)6]·7H2O}n (1·7H2O), has been synthesized and characterized by single crystal X-ray diffraction, IR spectroscopy, and magnetic measurements. The X-ray analysis shows 1 consists of a 2D homochiral (6,3) network with chiral [Mn3Na] clusters and chiral Ca ions as alternating nodes. Magnetic property study reveals the existence of weak antiferromagnetic couplings between Mn(III) ions with the interaction parameter J being − 0.438 cm− 1 within the complex.A new tri-metallic Mn/Ca/Na coordination polymer, {[Mn3NaCa(sal)6(H2O)6]·7H2O}n (1·7H2O), has been synthesized and characterized by single crystal X-ray diffraction, IR spectroscopy, and magnetic measurements. The X-ray analysis shows 1 consists of a 2D homochiral (6,3) network with chiral [Mn3Na] clusters and chiral Ca ions as alternating nodes. Magnetic property study reveals the existence of weak antiferromagnetic couplings between Mn(III) ions with the interaction parameter J being − 0.438 cm− 1 within the complex.
Co-reporter:Mei Wang, Chengbing Ma, Huimin Wen and Changneng Chen
Dalton Transactions 2009 (Issue 6) pp:994-1003
Publication Date(Web):12 Dec 2008
DOI:10.1039/B814794A
A series of new manganese phosphonate clusters with unprecedented topologies, [Mn20Na4O12(t-BuPO3)12(O2CMe)16(H2O)12]·5H2O (1), [Mn15O6(MePO3)2(MeCOO)18(H2O)12][MePO3H]2·12H2O (2), and [Mn(t-BuPO3H)2(phen)2]·MeCOOH (3) have been synthesized and characterized. The core of 1 is composed of two folded “butterfly-like” [Mn4(μ3-O)2] units and two trigonal prism [Mn6O6] units connected by four μ3-O, resulting in a twisted oval of twenty homovalent manganese(III) ions. The pentadecanuclear core of complex 2 is mixed-valent, containing six MnIII and nine MnII ions and features six μ4-O and two capping MePO32− anions adopting the binding mode [6.222], forming a rudder-like cage structure with a chiral D3 symmetry. Compound 3 is a manganese(II) phosphonate and features a 1D chain configuration packed by hydrogen bonds and π–π stacking interactions. Magnetic susceptibility measurements reveal that compounds 1, 2 and 3 display antiferromagnetic interactions between the adjacent manganese ions, while the in-phase signal χ′MT and out-of-phase signal χ″M of complex 1 exhibit frequency-dependence below approximately 3 K, but no frequency-dependence is observed in the ac signals of complex 2.
Co-reporter:Yue Zhang, Ming-Qiang Hu, Hui-Min Wen, You-Tao Si, Cheng-Bing Ma, Chang-Neng Chen, Qiu-Tian Liu
Journal of Organometallic Chemistry 2009 694(16) pp: 2576-2580
Publication Date(Web):
DOI:10.1016/j.jorganchem.2009.03.050
Co-reporter:Mei Wang, Cheng-Bing Ma, Xiao-Yu Li, Chang-Neng Chen, Qiu-Tian Liu
Journal of Molecular Structure 2009 920(1–3) pp: 242-247
Publication Date(Web):
DOI:10.1016/j.molstruc.2008.11.008
Co-reporter:Mei Wang ; Cheng-Bing Ma ; Da-Qiang Yuan ; Hui-Sheng Wang ; Chang-Neng Chen ;Qiu-Tian Liu
Inorganic Chemistry 2008 Volume 47(Issue 13) pp:5580-5590
Publication Date(Web):June 10, 2008
DOI:10.1021/ic701343s
A family of manganese complexes, [Mn5O3(t-BuPO3)2(MeCOO)5(H2O)(phen)2] (1), [Mn5O3(t-BuPO3)2(PhCOO)5(phen)2] (2), [Mn4O2(t-BuPO3)2(RCOO)4(bpy)2] (R = Me, (3); R = Ph, (4)), NBun4[Mn4O2(EtCOO)3(MeCOO)4(pic)2] (5), NR′4[Mn4O2(i-PrCOO)7(pic)2] (R′ = Bun, (6); R′ = Et, (7)), were synthesized and characterized. The seven manganese clusters were all prepared from a reaction system containing tert-butylphosphonic acid, Mn(O2CR)2 (R = Me, Ph) and NR′4MnO4 (R′ = Bun, Et) with similar procedures except for using different N-containing ligands (1,10-phenanthroline (phen), 2,2′-bipyridine (bpy) and picolinic acid (picH)) as coligands. The structures of these complexes vary with the N-containing donors. Both the cores of complexes 1 and 2 feature three μ3-O and two capping t-BuPO32− groups bridging five MnIII atoms to form a basket-like cage structure. Complexes 3 and 4 both have one [Mn4(μ3-O)2]8+ core with four coplanar MnIII atoms disposed in an extended “butterfly-like” arrangement and two capping μ3-t-BuPO32− binding to three manganese centers above and below the Mn4 plane. Complexes 5, 6, and 7 all possess one [Mn4(μ3-O)2]8+ core just as complexes 3 and 4, but they display a folded “butterfly-like” conformation with the four MnIII atoms nonplanar. Thus, the seven compounds are classified into three types, and three representative compounds 1·2H2O·MeOH·MeCN, 3·6H2O·2MeCOOH, and 5·0.5H2O have been characterized by IR spectroscopy, ESI-MS spectroscopy, magnetic measurements and in situ UV−vis−NIR spectroelectrochemical analysis. Magnetic susceptibility measurements reveal the existence of both ferromagnetic and antiferromagnetic interactions between the adjacent MnIII ions in compound 1·2H2O·MeOH·MeCN, and antiferromagnetic interactions in 3·6H2O·2MeCOOH and 5·0.5H2O. Fitting the experimental data led to the following parameters: J1 = −2.18 cm−1, J2 = 6.93 cm−1, J3 = −13.94 cm−1, J4 = −9.62 cm−1, J5 = −11.17 cm−1, g = 2.00 (1·2H2O·MeOH·MeCN), J1 = −5.41 cm−1, J2 = −35.44 cm−1, g = 2.13, zJ′ = −1.55 cm−1 (3·6H2O·2MeCOOH) and J1 = −2.29 cm−1, J2 = −35.21 cm−1, g = 2.02, zJ′ = −0.86 cm−1 (5·0.5H2O).
Co-reporter:Mei Wang, Chengbing Ma and Changneng Chen
Dalton Transactions 2008 (Issue 34) pp:4612-4620
Publication Date(Web):10 Jul 2008
DOI:10.1039/B804532A
Two new Mn(III) complexes with unprecedented topologies containing the tert-butylphosphonate ligand (t-BuPO32−), [Mn9O6(t-BuPO3)2(O2CMe)11(MeCOOH)(H2O)]·8H2O (1), and [NBun4][Mn13O6(t-BuPO3)10(OH)2(N3)6(MeCOOH)2(H2O)2]·6H2O (2) have been prepared by treatment of Mn(O2CMe)2 and NBun4MnO4 with tert-butylphosphonic acid in the presence of different bases. The core of 1 consists of two [Mn3O] units connected to a near linear [Mn3] unit by four μ3-O, while the core of 2 possesses a Mn centred disklike [Mn7O6] unit linked to six additional manganese atoms via six μ4-O. Compounds 1 and 2 are both homovalent manganese(III) cage clusters, of which the six-coordinated Mn centers are all Jahn–Teller distorted. Magnetic susceptibility measurements reveal that compounds 1 and 2 display overall ferromagnetic and antiferromagnetic interactions, respectively, between the adjacent MnIII ions. Both the in-phase signal χ′MT and out-of-phase signal χ″M of the two complexes exhibit frequency-dependence below approximately 3 K.
Co-reporter:Cheng-Bing Ma;Ming-Qiang Hu;Hui Chen, ;Qiu-Tian Liu
European Journal of Inorganic Chemistry 2008 Volume 2008( Issue 33) pp:5274-5280
Publication Date(Web):
DOI:10.1002/ejic.200800508
Abstract
A new discrete hexanuclear, mixed-valence Mn oxide cluster, [Mn6O2(O2CEt)10(H2O)4] (1), has been prepared and used as the building unit for the self-assembly of a rare propionato-bridged zigzag-like chain polymer, [Mn6O2(O2CEt)10(H2O)4]n (2), with the retention of the Mn6 core of 1. Both complexes are characterized by single-crystal X-ray structure determinations and magnetic measurements. The discrete complex 1·3H2O crystallizes in orthorhombic space group Pnna with a = 14.2089(6), b = 21.4910(11), and c = 16.4247(6) Å, whereas the polymeric complex 2·2nEtCO2H crystallizes in orthorhombic space group Pbca with a = 13.651(4), b = 25.827(8), and c = 30.312(10) Å. Variable-temperature magnetic susceptibility analyses show the presence of moderately strong antiferromagnetic interactions within the Mn6 cluster unit in both complexes.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Co-reporter:Mei Wang, Cheng-Bing Ma, Chang-Neng Chen, Qiu-Tian Liu
Journal of Molecular Structure 2008 Volume 891(1–3) pp:292-297
Publication Date(Web):26 November 2008
DOI:10.1016/j.molstruc.2008.03.055
A single-chain cobalt phosphonate complex [Co(phen)(4,4′-bpy)(PhPO3H)2]n·0.5H2O 1 (phen = 1,10-phenanthroline, 4,4′-bpy = 4,4′-bipyridine) and a mononuclear cobalt complex [Co(pic)2(H2O)2]·0.5H2O 2 (picH = picolinic acid) have been synthesized with identical procedure from similar system containing phenylphosphonic acid and N-containing ligands. Both complexes have been characterized by single crystal X-ray diffraction, IR spectroscopy, magnetic measurement and thermal analysis. Compound 1 crystallizes in the tetragonal system with a P43212 space group, and exhibits a 1-D cobalt chain connected by 4,4′-bpy bridges propagated along a axis direction, and the chains are linked by strong hydrogen bonds to form a two-dimensional grid like coordination network, whereas compound 2 crystallizes in the monoclinic system with space group P21/n, and the mononuclear molecules in 2 are linked by hydrogen bonds to form infinite double-chains and the double-chains are further crosslinked to create a two-dimensional supramolecular network. The magnetic measurement reveals overall weak antiferromagnetic exchange interactions between the cobalt ions in both complexes 1 and 2.
Co-reporter:Mei Wang, Cheng-Bing Ma, Hui-Sheng Wang, Chang-Neng Chen, Qiu-Tian Liu
Journal of Molecular Structure 2008 Volume 873(1–3) pp:94-100
Publication Date(Web):17 February 2008
DOI:10.1016/j.molstruc.2007.03.011
Two linear trinuclear compounds [Co3(CH3COO)6(H2O)(phen)2] · H2O 1 and [Mn3(CH3COO)6(H2O)(phen)2] · H2O (phen = 1,10-phenanthroline) 2 have been synthesized and characterized by single crystal X-ray diffraction, IR spectroscopy, thermal analysis and magnetic measurements. The X-ray analyses of 1 and 2 show that the two compounds have the same coordination environment but different central metal ions (Co(II) and Mn(II), respectively). The structures of 1 and 2 both consist of a trinuclear cobalt/manganese unit coordinated by two terminal phen groups, one H2O on the central Co(II)/ Mn(II) and six CH3COO− groups featuring four kinds of bonding mode. The magnetic measurements of the two complexes reveal overall antiferromagnetic exchange interactions between the metal ions.
Co-reporter:Ming-Qiang Hu, Cheng-Bing Ma, You-Tao Si, Chang-Neng Chen, Qiu-Tian Liu
Journal of Inorganic Biochemistry 2007 Volume 101(Issue 10) pp:1370-1375
Publication Date(Web):October 2007
DOI:10.1016/j.jinorgbio.2007.05.010
Diiron model complexes (μ-SCH2CH2CH2S)Fe2(CO)5L with thioether-substitution, L = S(CH2CH3)2 (2), S(CH2CH3)(CH2CH2Cl) (3), S(CH2CH3)(C6H5) (4), or sulfoxide-substitution, L = SO(CH2CH2CH3)2 (5), SO(CH3)2 (6), were synthesized as active site analogues of Fe-only hydrogenase. The organosulfur ligands were introduced into the diiron centers via moderately stable intermediates following two routes. The X-ray crystallographic structures of complexes 2–6 show the apical positions of terminal organosulfur ligands. The electrochemical behaviors of the model complexes were investigated, especially for the interesting properties of the derivative of 6 which is proposed to be the first model with weak donor ligand similar to CO.
Co-reporter:Mei Wang, Chengbing Ma, Daqiang Yuan, Mingqiang Hu, Changneng Chen and Qiutian Liu
New Journal of Chemistry 2007 vol. 31(Issue 12) pp:2103-2110
Publication Date(Web):15 Aug 2007
DOI:10.1039/B706514K
Four tetranuclear manganese(III) complexes containing phosphonate ligands (RPO32−, R = Me, Et and n-Bu), [Mn4O2(MePO3)2(O2CMe)4(bpy)2]·4MeCOOH (1), [Mn4O2(EtPO3)2(O2CMe)4(bpy)2]·7H2O (2), [Mn4O2(n-BuPO3)2(O2CMe)4(bpy)2]·4H2O·(COOH)2 (3) and [Mn4O2(MePO3)2(O2CPh)4(phen)2]·4PhCOOH·2MeCN (4), have been synthesized and characterized by IR spectroscopy, ESI-MS spectrometry, electrochemical analysis, magnetic measurements and TGA. The X-ray analysis shows that the four complexes all have one [Mn4(μ3-O)2]8+ core with four coplanar Mn atoms disposed in an extended “butterfly-like” arrangement and two O atoms triply bridging each “wing”, and the peripheral ligation is provided by four μ2-MeCO2− or four μ2-PhCO2−, two terminal bpy or phen (bpy = 2,2′-bipyridine, phen = 1,10-phenanthroline) groups at both ends of the molecule, and two bicapping μ3-phosphonate ligands, which each binds to three manganese centers above and below the plane. The cyclic voltammetry of 1 and 3 each displays four reduction and one oxidation processes, of which the four reduction processes are possibly attributed to the reduction of four MnIII of the compounds to MnII. The ESI-MS data indicate that the family of complexes are stable in solution. Magnetic susceptibility measurements reveal that compounds 1 and 3 display antiferromagnetic interactions between the adjacent MnIII ions mediated through the μ3-O, O–C–O and O–P–O bridges.
Co-reporter:Youtao Si, Chengbing Ma, Mingqiang Hu, Hui Chen, Changneng Chen and Qiutian Liu
New Journal of Chemistry 2007 vol. 31(Issue 8) pp:1448-1454
Publication Date(Web):24 Apr 2007
DOI:10.1039/B616236C
To further understand the effects of 1,3-azadithiolate (ADT) bridges on the structures and properties of diiron complexes, a novel family of (N-CnH2n−1)-1,3-azapropanedithiolate-bridged diiron complexes [Fe2(CO)6(CH2S)2N–CnH2n−1] (n = 5, 6, 7) and their PMe3-disubstituted complexes [Fe2(CO)4(PMe3)2(CH2S)2N–CnH2n−1] (n = 5, 6, 7) were synthesized as mimics of [FeFe]-hydrogenases. Our studies suggest that the coordination configurations, CO stretching frequencies, 1H and 31P NMR signals, redox potentials and electrocatalytic H2-production processes of diiron complexes are closely pertinent to the electron-donating abilities and steric chemistry of the ADT bridges.
Co-reporter:Lei Sun, Hui Chen, Chengbing Ma, Changneng Chen
Inorganic Chemistry Communications (March 2017) Volume 77() pp:
Publication Date(Web):March 2017
DOI:10.1016/j.inoche.2017.02.004
Reactions of manganese nitrate and lanthanide nitrate hexahydrate with 2-(hydroxymethyl)pyridine (hmpH) and trimethylacetic acid as co-ligands in the mixture solutions of acetonitrile and ethanol generated two hexanuclear Mn-Ln compounds [Mn4La2O2(hmp)7(tBuCO2)2.5(NO3)4.5] [Ln = La (1), Nd (2)]. Compounds 1 and 2 are isostructural and possess a core of [MnIII4LaIII2(μ4-O)(μ3-O)(μ3-OR)(μ2-O)7]2 −, which comprises three face-sharing defected cubane units. The species are new additions to the Mn/Ln clusters and the broader class of 3d/4f molecular systems. The solid-state direct current magnetic susceptibility analyses indicate the antiferromagnetic interactions within two compounds. The systematic investigation summarized that the variation of auxiliary ligand carboxylate R group affects structural distortions and switch the magnetic behaviour.
Co-reporter:Xiao-Wei Song, Yan Meng, Chuan-Lei Zhang, Cheng-Bing Ma, Chang-Neng Chen
Inorganic Chemistry Communications (February 2017) Volume 76() pp:
Publication Date(Web):February 2017
DOI:10.1016/j.inoche.2017.01.011
•A linear aminopyridine ligand and its corresponding metal complexes of Co2 + and Zn2 + were synthesized.•The cobalt complex displayed electrocatalytic water reduction activity in acetonitrile.•The cobalt complex was active for photocatalytic hydrogen production.A linear pentadentate aminopyridine ligand 2,6-bis[(methyl(pyrid-2-ylmethyl)amino)-N-methyl]pyridine (PyMepam) has been prepared and characterized. This ligand readily coordinates with Co(II) or Zn(II) ions, and the resulting complexes of general formula [M(PyMepam)](BF4)2 (M = Co (1) and M = Zn (2)) have been thoroughly characterized and investigated for electro- and photocatalytic water reduction in acetonitrile. Electrochemical studies reveal that the complex 1 is active for electrocatalytic water reduction in acetonitrile. Under visible-light irradiation (λ > 400 nm), the complex 1 displays hydrogen evolution activity when in presence of [Ir(ppy)2(bpy)]PF6 as photosensitizer and triethylamine (TEA) as electron donor, whereas 2 shows negligible catalytic activity under the same conditions. Highest turnover numbers (TONs) of 290 for H2 evolution are achieved from an optimized system containing 1 (0.1 mM), [Ir(ppy)2(bpy)](PF6) (0.5 mM), and 10 vol% TEA in CH3CN-H2O (1/1, v/v) mixed solvents at pH 10.A cobalt complex of a linear pentadentate aminopyridine ligand was active for photocatalytic hydrogen production with a highest TON of 290.
Co-reporter:Mei Wang, Chengbing Ma and Changneng Chen
Dalton Transactions 2008(Issue 34) pp:NaN4620-4620
Publication Date(Web):2008/07/10
DOI:10.1039/B804532A
Two new Mn(III) complexes with unprecedented topologies containing the tert-butylphosphonate ligand (t-BuPO32−), [Mn9O6(t-BuPO3)2(O2CMe)11(MeCOOH)(H2O)]·8H2O (1), and [NBun4][Mn13O6(t-BuPO3)10(OH)2(N3)6(MeCOOH)2(H2O)2]·6H2O (2) have been prepared by treatment of Mn(O2CMe)2 and NBun4MnO4 with tert-butylphosphonic acid in the presence of different bases. The core of 1 consists of two [Mn3O] units connected to a near linear [Mn3] unit by four μ3-O, while the core of 2 possesses a Mn centred disklike [Mn7O6] unit linked to six additional manganese atoms via six μ4-O. Compounds 1 and 2 are both homovalent manganese(III) cage clusters, of which the six-coordinated Mn centers are all Jahn–Teller distorted. Magnetic susceptibility measurements reveal that compounds 1 and 2 display overall ferromagnetic and antiferromagnetic interactions, respectively, between the adjacent MnIII ions. Both the in-phase signal χ′MT and out-of-phase signal χ″M of the two complexes exhibit frequency-dependence below approximately 3 K.
Co-reporter:Ming-Qiang Hu, Hui-min Wen, Cheng-Bing Ma, Na Li, Qing-Yun Yan, Hui Chen and Chang-Neng Chen
Dalton Transactions 2010 - vol. 39(Issue 40) pp:NaN9486-9486
Publication Date(Web):2010/09/08
DOI:10.1039/C0DT00505C
A series of model complexes [(μ-pdt)Fe2(CO)5]2M(sip)2 (M = Fe, Ni) were synthesized as H-cluster analogues of [FeFe]-hydrogenase. Their electrochemical behaviours were investigated and it is proposed that the bridging metal bis(tris-chelate) groups act as electron transfer sites in theses mimics.
Co-reporter:Mei Wang, Da-Qiang Yuan, Cheng-Bing Ma, Ming-Jian Yuan, Ming-Qiang Hu, Na Li, Hui Chen, Chang-Neng Chen and Qiu-Tian Liu
Dalton Transactions 2010 - vol. 39(Issue 31) pp:NaN7285-7285
Publication Date(Web):2010/06/28
DOI:10.1039/C002474K
The use of phosphonic acids in the synthesis of mixed-metal CeMn complexes has led to the formation of two phosphonate complexes with unusual topologies: [Ce2Mn6O6(OH)5(t-BuPO3)6(O2CMe)3]·53H2O (1·53H2O) and [Ce22Mn12O34(MePO3)12(O2CMe)33(OMe)6(NO3)(H2O)12]n (2). The two mixed-metal CeMn complexes were both prepared from a reaction system containing Mn(O2CMe)2 and (NH4)2[Ce(NO3)6] with similar procedures except for using different phosphonic acids (tert-butylphosphonic acid and methylphosphonic acid, respectively) as coligands. Both complexes possess rare topology of triangular type, with compound 1 being a 0D discrete cluster, whereas, compound 2 is a 1D polymer. The octanuclear core of complex 1 is composed of three symmetry equivalent distorted cubanes {CeIV2MnIV2O2(OH)2} sharing a trigonal-bipyramidal unit {CeIV2(OH)3} in the centre. Compound 2 is a one-dimensional chain polymer of identical Ce22Mn12O34 units linked together by NO3− and MeCO2− groups, while the Ce22Mn12O34 unit is constituted by two centrosymmetric Ce9IVCe2IIIMnIV6O17 subunits, which features three identical distorted cubanes {CeIV2MnIV2O4} connecting to a central trigonal-bipyramidal unit {CeIV3O2}, and two additional CeIII ions capping the top and bottom of the central trigonal bipyramid by six MePO32− ligands. Complexes 1 and 2 are the first high-nuclearity Mn/Ln aggregates reported to date using phosphonates as ligands. Magnetic susceptibility measurements reveal that compound 1 displays dominant ferromagnetic interactions between the adjacent metal ions with the best fit parameters for the exchanges are J1 = 6.186 cm−1, J2 = 4.172 cm−1, and with a result of S = 9 ground state confirmed by the M versus HT−1 data, which indicates the spins of all the six MnIV ions in the cluster are parallel to each other. In contrast, the data for 2 reveals overall antiferromagnetic couplings within the cluster and a resulting S = 6 ground state. Both the in-phase signal χ′MT and out-of-phase signal χ′′M of the two complexes exhibit frequency-dependent below approximate 3 K.
Co-reporter:Hong-hua Cui, Ming-qiang Hu, Hui-min Wen, Guo-liang Chai, Cheng-bing Ma, Hui Chen and Chang-neng Chen
Dalton Transactions 2012 - vol. 41(Issue 45) pp:NaN13907-13907
Publication Date(Web):2012/09/06
DOI:10.1039/C2DT31618H
Two [FeFe] hydrogenase mimics, [Fe2(μ-pdt)(CO)5L1] (L1 = PPh2SPhNH2) (Ph = phenyl) (2) and [Fe2(μ-pdt)(CO)5L2] (L2 = PPh2PhNH2) (3), and two molecular photocatalysts, [(CO)5(μ-pdt)Fe2PPh2SPhNHCO(bpy)(ppy)2Ir]PF6 (bpy = bipyridine, ppy = 2-phenylpyridine) (2a) and [(CO)5(μ-pdt)Fe2PPh2PhNHCO(bpy)(ppy)2Ir](PF6) (3a), have been designed and synthesized, anchoring Ir(ppy)2(mbpy)PF6 (mbpy = 4-methyl-4′-carbonyl-2,2′-bipyridine) (PS) to one of the iron centers of complexes 2 and 3 by forming amide bonds. Molecular dyads 2a, 3a and the intermolecular systems 2, 3 with PS have also been successfully constructed for photoinduced H2 production using triethylamine (TEA) as a sacrificial electron donor by visible light (>400 nm) in CH3CN–H2O solution. The time-dependence of H2 generation and spectroscopic studies suggest that the activity of H2 evolution can be tuned by addition of a S atom to the phosphane ligand. The highest turnover numbers (TON) of hydrogen evolution obtained are 127, using 2a as a photocatalyst in a supramolecular system, and 138, based on catalyst 2 in a multi-component system. Density functional theory (DFT) computational studies demonstrate that the S atom in the second coordination sphere makes complex 2 accept an electron more easily than 3 and improves the activity in light-induced hydrogen production.
Co-reporter:Hui-Min Wen, Jin-Yun Wang, Ming-Qiang Hu, Bin Li, Zhong-Ning Chen and Chang-Neng Chen
Dalton Transactions 2012 - vol. 41(Issue 38) pp:NaN11819-11819
Publication Date(Web):2012/08/03
DOI:10.1039/C2DT31507F
A diiron dithiolate complex 1o with a dithienylethene (DTE) phosphine ligand has been elaborately designed and fully investigated by spectroscopic and DFT computational studies. Upon irradiation with UV light, the DTE moiety in complex 1o undergoes an excellent photocyclization reaction to attain ring-closed state 1c in high yield (>95%), accompanied by a colour change from orange to deep blue. On the other hand, upon irradiation with visible light (>460 nm), ring-closed form 1c in CH3CN solution reverts perfectly into ring-open form 1o. Both 1o and 1c were characterised by IR, 1H, 31P, 19F NMR and electrochemical spectroscopy. The electrochemical behaviours of both the open and closed forms were investigated by cyclic voltammetry. Upon photocyclization reaction, a 290 mV (from −2.29 V to −2.00 V) positive shift is induced in the potential of electrochemical catalytic proton reduction, due to the electron-withdrawing effect of the ring-closed DTE moiety. Consequently, complex 1 can reversibly photoswitch the potential of proton reduction on the [FeFe] moiety.
Co-reporter:Jinying Liu, Chengbing Ma, Hui Chen, Mingqiang Hu, Huimin Wen, Honghua Cui and Changneng Chen
Dalton Transactions 2013 - vol. 42(Issue 11) pp:NaN3790-3790
Publication Date(Web):2013/02/07
DOI:10.1039/C3DT32985B
A family of heptanuclear [MnII3LnIII4] clusters with planar disc-like cores have been synthesized by a solvothermal route, where Ln = La, Pr, Nd, and Gd, and such fascinating topology is unprecedented in 3d–4f complexes. Dc magnetic susceptibility data show different magnetic behaviors derived from the difference in Ln ions.
Co-reporter:Mei Wang, Chengbing Ma, Huimin Wen and Changneng Chen
Dalton Transactions 2009(Issue 6) pp:NaN1003-1003
Publication Date(Web):2008/12/12
DOI:10.1039/B814794A
A series of new manganese phosphonate clusters with unprecedented topologies, [Mn20Na4O12(t-BuPO3)12(O2CMe)16(H2O)12]·5H2O (1), [Mn15O6(MePO3)2(MeCOO)18(H2O)12][MePO3H]2·12H2O (2), and [Mn(t-BuPO3H)2(phen)2]·MeCOOH (3) have been synthesized and characterized. The core of 1 is composed of two folded “butterfly-like” [Mn4(μ3-O)2] units and two trigonal prism [Mn6O6] units connected by four μ3-O, resulting in a twisted oval of twenty homovalent manganese(III) ions. The pentadecanuclear core of complex 2 is mixed-valent, containing six MnIII and nine MnII ions and features six μ4-O and two capping MePO32− anions adopting the binding mode [6.222], forming a rudder-like cage structure with a chiral D3 symmetry. Compound 3 is a manganese(II) phosphonate and features a 1D chain configuration packed by hydrogen bonds and π–π stacking interactions. Magnetic susceptibility measurements reveal that compounds 1, 2 and 3 display antiferromagnetic interactions between the adjacent manganese ions, while the in-phase signal χ′MT and out-of-phase signal χ″M of complex 1 exhibit frequency-dependence below approximately 3 K, but no frequency-dependence is observed in the ac signals of complex 2.
Co-reporter:Hong-hua Cui, Jin-yun Wang, Ming-qiang Hu, Cheng-bing Ma, Hui-min Wen, Xiao-wei Song and Chang-neng Chen
Dalton Transactions 2013 - vol. 42(Issue 24) pp:NaN8691-8691
Publication Date(Web):2013/03/21
DOI:10.1039/C3DT50140J
Exploration of the complex Ni2(MBD)4 (MBD = 2-mercaptobenzimidazole) (C1) having different coordinated Ni atoms as a photocatalyst for hydrogen evolution is made. For comparison, the bimetallic Ni2(MBT)4 (MBT = 2-mercaptobenthiazole) (C2) complex with the same coordinated Ni atoms was synthesized. Both of the complexes have been successfully constructed for photo-induced hydrogen production using organic dyes as photosensitizers and triethanolamine (TEOA) as the effective electron donor by visible light (>400 nm) in acetonitrile–water solution. The time-dependence of H2 generation and DFT computational studies demonstrate that the complex C1 is more active than C2 for H2 evolution. The mechanisms of photocatalytic hydrogen generation for C1 and C2 involve different protonation sites resulting from the differences between the two structures.
Co-reporter:Jinying Liu, Chengbing Ma, Hui Chen, Mingqiang Hu, Huimin Wen, Honghua Cui, Xiaowei Song and Changneng Chen
Dalton Transactions 2013 - vol. 42(Issue 7) pp:NaN2430-2430
Publication Date(Web):2012/11/12
DOI:10.1039/C2DT32269B
A new family of isostructural Mn–Ln heterometallic clusters, [MnII2MnIII2LnIII2(Piv)8(thme)2(H2tea)2] (H3thme = 1,1,1-tris(hydroxymethyl)ethane, Hpiv = pivalic acid, H3tea = triethanolamine, and Ln = Pr, Nd, Sm, Eu, Gd, Tb, and Dy) have been prepared by reaction of the hexanuclear manganese precursor, [Mn6O2(Piv)10(4-Me-Py)2.5(Hpiv)1.5], with H3thme, H3tea, and Ln(NO3)3·6H2O under the solvothermal conditions. Complexes 1Pr–7Dy were characterized by single-crystal X-ray diffraction and their core [Mn2IIIMn2IILn2III(μ3-OR)4(μ2-OR)6]6+ composed of four face-sharing defected cubane units. Antiferromagnetic (AF) exchange interactions were suggested for all of the complexes by solid-state dc magnetic susceptibility measurements. Complexes 6Tb and 7Dy, show frequency-dependent ac susceptibility signals suggestive of slow magnetic relaxation.
Co-reporter:Lei Sun, Hui Chen, Chengbing Ma and Changneng Chen
Dalton Transactions 2015 - vol. 44(Issue 48) pp:NaN20971-20971
Publication Date(Web):2015/11/06
DOI:10.1039/C5DT03130C
A new family of isostructural Mn/Ln dodenuclear clusters: [Mn8Ln4(O)8(hmp)4(O2CPh)12(NO3)4(PhCO2H)(C2H5OH)] [Ln = La (1), Pr (2), Nd (3), Gd (4), Dy(5), hmpH = 2-(hydroxymethyl)pyridine] have been synthesized by the reaction of Mn(NO3)2 and Ln(NO3)3·6H2O with hmpH and benzoic acid as co-ligands. Compounds 1–5 possess a spindle-shaped core of [MnIII8LnIII4(μ4-O)4(μ3-O)4(μ3-OR)2(μ2-OR)8]10+, which is composed of six face-sharing defected cubane units and two square-pyramidal units. The compounds represent the highest nuclearity Mn/Ln clusters with the use of hmpH to date. That the ferromagnetic interactions dominated within complexes 1–4 were suggested by solid-state dc magnetic susceptibility analyses. Compound 4 displays a magnetic-caloric effect (MCE) with 13.94 J kg−1 K−1 as the entropy change at 6 K for ΔH = 8 T. Compounds 1 and 5 exhibit an out-of-phase χ′′M peak maximum above 2.0 K. Fitting of the ac susceptibility data to an Arrhenius law gives an energy barrier Ueff = 6.88/7.44 K for compounds 1 and 5 respectively.
Co-reporter:Hui Chen, Cheng-Bing Ma, Ming-Qiang Hu, Hui-Min Wen, Hong-Hua Cui, Jin-Ying Liu, Xiao-Wei Song and Chang-Neng Chen
Dalton Transactions 2013 - vol. 42(Issue 14) pp:NaN4914-4914
Publication Date(Web):2013/01/07
DOI:10.1039/C2DT32739B
Reactions of [Mn6O2(piv)10(py)2.5(piv)1.5], Ln(NO3)3·6H2O and N-mdeaH2 in MeCN in the presence of Me3SiCl generated a family of octanuclear Mn/Ln complexes [Mn6IIIMnIILn(N-mdea)3(N-mdeaH)(piv)8O2(OH)3(NO3)(H2O)]·xCH3CN·xH2O [Ln = Gd (1), Dy (2), Er (3), pivH = pivalic acid, N-mdeaH2 = N-methyl diethanolamine]. Each complex possesses a [Mn6IIIMnIILn(μ3-O)2(μ3-OH)3]16+ core containing two butterfly-like subunits of [Mn3Ln(μ3-OH)2] and [Mn4(μ3-O)2] sharing a common vertex, and an outer Mn atom ligated to one of the subunits through a μ3-OH− ligand. The core topology represents a new Mn/Ln core type. The magnetic susceptibility study of 1–3 indicates the presence of dominant antiferromagnetic interactions within the complexes. For complex 1, which contains an isotropic GdIII atom, fitting of the obtained M/(NμB) vs. H/T data gave S = 4, g = 1.90, and D = −0.31 cm−1. The results were further supported by ac data. Complex 3 exhibits out-of-phase ac susceptibility signals, indicating it may be a SMM.
Co-reporter:Hui Chen, Cheng-Bing Ma, Ming-Qiang Hu, Hui-Min Wen and Chang-Neng Chen
Dalton Transactions 2014 - vol. 43(Issue 44) pp:NaN16744-16744
Publication Date(Web):2014/09/15
DOI:10.1039/C4DT01816H
Using 3-methyloxysalicylaldoxime (mosaoH2) and N-methyl diethanolamine (N-mdeaH2) as coligands, a family of heptanuclear Mn/Ln heterometallic compounds [MnIIMnIII2LnIII4(mosao)2(mosaoH)4(piv)4(N-mdea)4]·xMeCN [Ln = Dy(1), Tb(2) and Y(3), pivH = pivalic acid] have been prepared. The crystal structures of 1–3 were obtained, and their core consists of two MnIIILn2(μ3-OR)2 (RO2− = N-mdea2−) triangles linked to a central MnII atom. A dc magnetic susceptibility study reveals that single-ion effects of the Ln ions are dominant in compounds 1 and 2. As for compound 3, which contains diamagnetic Y ions, the magnetic interactions between Mn ions via oximate NO bridges are revealed to be ferromagnetic. Fitting of the χmT vs. T data gives g = 1.96 and J = 1.12 cm−1, affording a S = 13/2 ground state. All of the three compounds exhibit frequency-dependent out-of-phase ac susceptibility signals indicative of slow magnetization relaxation and potential SMM behavior. Among them, 1 and 3 display the out-of-phase χ′′m peak maximum above 2.0 K. Fitting of the ac susceptibility data to the Arrhenius law gives an energy barrier Ueff = 9.27/13.83 K for 1 and 3, respectively.
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