Co(II)-catalyzed C–H C2 selective arylation of indoles with boronic acids through monodentate chelation assistance has been achieved for the first time. The unique features of this methodology include mild reaction conditions, highly C2 regioselectivity, and employment of a Grignard reagent-free catalytic system. A wide range of substrates, including unreactive arenes, are well tolerated, which enables the construction of the coupling products efficiently. This new strategy provides an alternative and versatile approach to construct biaryls using inexpensive cobalt catalyst.

The manganese-catalyzed addition of C-2 position of indoles to maleimides has been achieved under additive-free conditions. The manganese catalyst exhibits excellent chemo- and regioselectivity, good functional group compatibility, and high catalytic efficiency. The substrate scope can also be extended to maleates, ethyl acrylate, 1,4-dihydro-1,4-epoxynaphthalene, pyrroles, and 2-phenylpyridine, which further demonstrates the universality of this straightforward approach.

As a powerful synthetic tool for the formation of aromatic C–N bonds, the reported transition-metal-catalyzed direct C–H amination has been ineffective for the synthesis of triarylamines for a long time. Herein, an elegant strategy for the preparation of triarylamines was disclosed using inexpensive Co(OAc)2·4H2O as the catalyst. It is noteworthy that unactivated arenes and simple anilines were employed as the starting materials with good functional group tolerance. In addition, an organometallic Co(III) species was isolated and identified by X-ray crystallography, thus providing some in-depth insights into the mechanism.Keywords: amination; cobalt catalysis; C−H activation; C−H/N−H cross-coupling; triarylamine;

A series of chiral (imidazoline–oxazoline) N,N-bidentate ligands L1–L5 derived from 2,2-dimethylmalonic acid were conveniently synthesized and characterized. With the aid of the new ligands, the first Co(II)-catalyzed asymmetric Michael addition of 2-acetyl azaarenes to β-CF3-β-disubstituted nitroalkenes was successfully achieved, producing chiral compounds with a trifluoromethylated all-carbon quaternary stereocenter in good yields with enantioselectivities of up to 98% ee.

AbstractThe first nickel-catalyzed ortho-sulfonylation of C(sp2)–H bonds with sodium sulfinates directed by (pyridin-2-yl)isopropylamine (PIP-amine) is described. This strategy exhibits a broad substrate scope and good functional group tolerance with high monosulfonylation selectivity. Besides arenes and heteroarenes, the reaction can also be extended to alkenes, providing diverse diaryl and alkyl aryl sulfones in high yields. Furthermore, a plausible Ni(I)/Ni(III) mechanism is outlined based on our experimental results and related precedents.

A new method of cobalt-catalyzed amination of arylamides with simple alkylamines is reported through C(sp2)–H bond functionalization. For the first time, inexpensive cobalt is exploited as the catalyst in the amination of C(sp2)–H bond using simple alkylamines.

A new cobalt(II)-catalyzed decarboxylative C–H activation/annulation of benzamides and alkynyl carboxylic acids has been described. Alkynyl carboxylic acids were first employed as the coupling partners using inexpensive Co(OAc)2·4H2O as the catalyst. This method enables a switchable cyclization to isoquinolones and isoindolinones with excellent selectivity. Moreover, a catalytic amount of Ag2O was adopted as co-catalyst and O2 (from air) as a terminal oxidant for the preparation of isoquinolones.

The transformation of aldoximes to primary amides has been evaluated using pincer ruthenium complexes a–c, among which the ionic Ru catalyst a proved to be the most efficient in water under air atmosphere. A variety of (hetero)arene aldoximes proceeded smoothly to afford amides in high yields with good functional group compatibilities. Furthermore, a direct synthetic route of amides from aldehydes, hydroxylamine hydrochloride and sodium carbonate was also described with broad substrates including conjugated and aliphatic aldehydes. This protocol is operationally simple and proceeds with a low catalyst loading (0.5 mol%).

A series of chiral S,N-thioimidazoline ligands have been synthesized using 2-bromobenzoic acid or 1-bromo-2-naphthoic acid as starting materials. The obtained ligands were evaluated in the Pd-catalyzed asymmetric allylic alkylations and exhibited high catalytic efficiency: yields of up to 94% and enantioselectivities of up to 86% were achieved under the optimized conditions.(S)-2-(2-Bromophenyl)-4-isopropyl-1-(p-tolyl)-4,5-dihydro-1H-imidazoleC19H21BrN2[α]D20 = −92 (c 1.22, CH2Cl2)Absolute configuration: (S)(S)-2-(2-Bromophenyl)-4-phenyl-1-(p-tolyl)-4,5-dihydro-1H-imidazoleC22H19BrN2[α]D20 = −131 (c 1.70, CH2Cl2)Absolute configuration: (S)(S)-2-(1-Bromonaphthalen-2-yl)-4-(tert-butyl)-1-(p-tolyl)-4,5-dihydro-1H-imidazoleC24H25BrN2[α]D20 = −14 (c 0.19, CHCl3)Absolute configuration: (S)(S)-4-(tert-Butyl)-2-(2-(phenylthio)phenyl)-1-(p-tolyl)-4,5-dihydro-1H-imidazoleC20H23BrN2[α]D20 = −48 (c 1.10, CH2Cl2)Absolute configuration: (S)(S)-2-(1-Bromonaphthalen-2-yl)-4-isopropyl-1-(p-tolyl)-4,5-dihydro-1H-imidazoleC23H23BrN2[α]D20 = −49 (c 0.22, CHCl3)Absolute configuration: (S)(S)-2-(1-Bromonaphthalen-2-yl)-4-phenyl-1-(p-tolyl)-4,5-dihydro-1H-imidazoleC26H21BrN2[α]D20 = −156 (c 0.11, CHCl3)Absolute configuration: (S)(S)-4-Isopropyl-2-(2-(phenylthio)phenyl)-1-(p-tolyl)-4,5-dihydro-1H-imidazoleC25H26N2S[α]D20 = −37 (c 0.48, CHCl3)Absolute configuration: (S)(S)-4-Phenyl-2-(2-(phenylthio)phenyl)-1-(p-tolyl)-4,5-dihydro-1H-imidazoleC28H24N2S[α]D20 = −76 (c 0.71, CHCl3)Absolute configuration: (S)(S)-4-Isopropyl-2-(1-(phenylthio)naphthalen-2-yl)-1-(p-tolyl)-4,5-dihydro-1H-imidazoleC29H28N2S[α]D20 = −4 (c 0.41, CHCl3)Absolute configuration: (S)(S)-4-Phenyl-2-(1-(phenylthio)naphthalen-2-yl)-1-(p-tolyl)-4,5-dihydro-1H-imidazoleC32H26N2S[α]D20 = −108 (c 0.65, CHCl3)Absolute configuration: (S)(S)-4-(tert-Butyl)-2-(2-(phenylthio)phenyl)-1-(p-tolyl)-4,5-dihydro-1H-imidazoleC26H28N2S[α]D20 = −18 (c 0.50, CHCl3)Absolute configuration: (S)(S)-2-(2-(Isopropylthio)phenyl)-4-phenyl-1-(p-tolyl)-4,5-dihydro-1H-imidazoleC25H26N2S[α]D20 = −64 (c 0.1, CH2Cl2)Absolute configuration: (S)(S)-4-(tert-Butyl)-2-(1-(phenylthio)naphthalen-2-yl)-1-(p-tolyl)-4,5-dihydro-1H-imidazoleC30H30N2S[α]D20 = +31 (c 0.53, CHCl3)Absolute configuration: (S)

A novel iron-involved tosylmethylation of imidazo[1,2-α]pyridines with p-toluenesulfonylmethyl isocyanide in a solvent mixture of H2O and PEG400 under an Ar atmosphere has been developed. This protocol provides a facile synthetic route for the functionalization of the imidazo[1,2-α]pyridine scaffold with broad substrate compatibility, which is less expensive and environmentally friendly. The current methodology could further enable regioselective C–H tosylmethylation of indole at the C3 position. Also, p-toluenesulfonylmethyl isocyanide was utilized as the tosylmethylating reagent for the first time.

A nickel(II)-catalyzed alkynylation/annulation cascade via double C–H cleavage has been successfully achieved. This methodology adopted a removable N,O-bidentate directing group with a broad range of amide substrates and terminal alkynes being well tolerated. The catalytic system allowed for atom-economical and environmentally benign one-pot construction of the corresponding 3-methyleneisoindolin-1-one derivatives using O2 as the external oxidant.

A catalyst free Friedel–Crafts (F–C) hydroxyalkylation of imidazo[1,2-α]pyridines with ethyl trifluoropyruvate is herein described using isopropyl ether as a solvent. Electron-donating and electron-withdrawing functional groups at various aromatic positions were well tolerated under our optimized conditions. The method enabled the generation of desired products in moderate to excellent yields under mild conditions, which makes this transformation an attractive, environmentally benign alternative for the synthesis of the target compounds.

A series of naphtho[1′,2′:4,5]imidazo[1,2-a]pyridines were synthesized smoothly from 2-arylimidazo[1,2-a]pyridines and alkynes involving rhodium(III)-catalyzed C–H bond functionalization. The process selected Co(OAc)2·4H2O as the co-catalyst for the first time and minimized the reaction time to 2 h under air atmosphere. Some products exhibited deep blue luminescence properties.

A new method for palladium-catalyzed β-arylation of aliphatic and cycloaliphatic amides without conventional silver salts utilizing 2-aminopyridine-1-oxide moiety (PyO) as an N,O-bidentate group has been developed. Reactions proceeded smoothly in DMSO solvent in the presence of K2HPO4·3H2O, providing the β-arylated aliphatic amide products in a moderate-to-good yield. An important cyclopalladium intermediate, successfully obtained with a modest yield, could be converted to the monoarylation product and be used as catalyst in arylation reaction. Moreover, the PyO directing group was easily removed under base condition to generate aliphatic acids.

Neutral and cationic ruthenium(II) complexes bearing a symmetrical 2,6-bis(imidazo[1,2-a]pyridin-2-yl)pyridine were synthesized and structurally characterized by NMR analysis and X-ray crystallographic determinations. These complexes have exhibited good catalytic activity in the transfer hydrogenation of ketones. In refluxing isopropyl alcohol, the conversion of the substrates reached up to 99%, and a TOF value of 356 400 h–1 with 0.1 mol % catalyst was achieved.

Copper-mediated selective mono- or diaryloxylation of benzamides has been achieved by using 2-aminopyridine 1-oxide as a new and removable N,O-bidentate directing group. The reaction system shows a broad substrate scope and provides a straightforward way for the synthesis of mono- and diaryloxylated benzoic acids.

The (ppy)-based Pt(II) complex (Pt-1) with deprotonated 2-(diphenylphosphino)benzoic acid as an anionic ligand displays phosphorescence of monomers with a remarkably higher quantum yield than that of the corresponding iridium complex (Ir-1). A prototype OLED using Pt-1 exhibits high performance with an external quantum efficiency of 4.93%.

Primary aromatic amides can be synthesized from aldehydes and hydroxylamine hydrochloride in the presence of Cs2CO3. Various aromatic aldehydes (include some heteroaromatic aldehydes) are able to generate the corresponding aromatic amides in moderate to excellent yields.

A series of chiral 2-aryl-6-(oxazolinyl)pyridine (aryl = phenyl or 1-naphthyl) ligands 2a–f were conveniently prepared from commercially available 6-bromo-2-picolinaldehyde in two steps. Reaction of 2a–f with PdCl2 in toluene in the presence of sodium bicarbonate afforded the corresponding CNN pincer Pd(II) complexes 3a–f via aryl C–H bond activation of the related ligands. All of the new compounds have been fully characterized by elemental analysis (MS for ligands), 1H and 13C NMR, and IR spectra. In addition, the molecular structures of Pd(II) complexes 3c–f have been determined by X-ray single-crystal diffraction. The obtained chiral pincer catalysts were successfully used in the asymmetric allylation of isatins with allyltributyltin, giving the corresponding 3-allyl-3-hydroxyoxindoles in high yields with enantioselectivities of up to 86% ee. These pincers could also catalyze the asymmetric Suzuki–Miyaura coupling reaction to provide the axially chiral biaryl products in good yields with good stereoselectivities (up to 68% ee).

A series of chiral NCN pincer Pd(II) complexes with 1,3-bis(2′-imidazolinyl)phenyl (Phebim) ligands were synthesized via the C–H activation or oxidative addition method. A dinuclear macrocyclic Pd(II) complex was also prepared by reaction of the Phebim-H ligand with PdCl2. All of the new compounds were fully characterized, and X-ray single-crystal structures were obtained for two of the complexes. The Pd(II) complexes were successfully applied to enantioselective hydrophosphination of various enones with diphenylphosphine, providing optically active phosphine derivatives in good yields with enantioselectivities of up to 94% ee.

A series of neutral pincer Pt(II) chloride complexes 3–7 were first synthesized via the reaction of 1,3-bis(N-substituted benzimidazol-2′-yl) benzene (bzimb) ligands 2a–e with K2PtCl4 in refluxing HOAc. By treatment of complex 3 with KI and aromatic terminal alkynes in methanolic NaOH, the Pt(II) iodide complex 8 and Pt(II) acetylide complexes 9–11 were then obtained. Cationic Pt(II) complexes 12–15 were finally produced by the chloro-substitution reaction of complex 3 with AgOTf and several neutral N-donor ligands. With these new compounds in hand, various characterizations including elemental analysis, NMR, and IR were carried out to investigate their properties. On the basis of the X-ray single-crystal structure analysis of complexes 3–5, 8, 9, and 12, weak intermolecular interactions including π···π stacking and/or hydrogen bonds were found to be responsible for their assembly. After full investigation of the electronic absorption and photoluminescent properties of the Pt(II) complexes 3–15, time-dependent density functional theory (TD-DFT) calculations were carried out to elucidate the origins of the UV–vis absorptions. We were delighted to find that the luminescence quantum yields in degassed CH2Cl2 solution were around 0.13 in most cases and the emission lifetimes were in the microsecond range, indicating that these complexes could be used as bright phosphorescent materials with various potential applications in the future.

A series of chiral PCN pincer Pd(II) complexes VI–XIII with aryl-based aminophosphine–imidazoline or phosphinite–imidazoline ligands were synthesized and characterized. They were examined as enantioselective catalysts for the hydrophosphination of enones. Among them, complex IX, which features a Ph2PO donor as well as an imidazoline donor with (4S)-phenyl and N-Tol-p groups, was found to be the optimal catalyst. Thus, in the presence of 2–5 mol % of complex IX a wide variety of enones reacted smoothly with diarylphosphines to give the corresponding chiral phosphine derivatives in high yields with enantioselectivities of up to 98% ee. In particular, heteroaryl species such as 2-thienyl-, 2-furyl-, and 2-pyridinyl-containing enones that have a strong coordination ability to the Pd center were also appropriate substrates for the current catalytic system. For example, hydrophosphination of 2-alkenoylpyridines with diphenylphosphine followed by oxidation with H2O2 afforded the corresponding pyridine-functionalized chiral phosphine oxides in good yields with good to excellent enantioselectivities (10 examples, up to 95% ee). Furthermore, it had been demonstrated that the obtained pyridine-containing phosphine oxide acted as a tridentate ligand in the reaction with PdCl2 to form an intriguing NCsp3O pincer Pd(II) complex via Csp3–H bond activation, which to our knowledge is the first example of a chiral DCsp3D′ Pd pincer (D ≠ D′; D and D′ denote donor atoms such as P, N, etc.).

Highly effective CuCl-mediated C—H alkoxylation of arenes and heteroarenes has been developed by using a 2-aminopyridine 1-oxide moiety as an N,O-bidentate directing group. The reaction proceeds smoothly using a broad range of substrates to afford o-alkoxylated benzoic and heteroaromatic amide products. Moreover, the reaction system shows remarkable compatibility when hexafluoroisopropanol is used as a coupling parter; halogen, nitro, ether, alkoxy, ester, and sulfonyl functional groups are all tolerated. The directing group can be easily removed by base hydrolysis, affording o-alkoxylated benzoic acids.

The reaction of 2-hydroxybenzophenone derivatives with europium ions has afforded a new family of luminescent nonanuclear Eu(III) clusters. Crystal structure analysis of the clusters reveals that the metal core comprises two vertex-sharing square pyramidal units. Most of these complexes show emissions typical of Eu3+ ion under visible light excitation (400–420 nm) at room temperature. Photophysical characterization and DFT study reveal a correlation between luminescent efficiencies of Eu(III) complexes and the electronic features of the ligands, which can be tuned by the nature of substituents in the 4-position of the ligands. The ligands with a fluorine substituent possess more suitable triplet energy levels, resulting in more intensive luminescence.

Reactions of [Zn(L)(H2O)] precursor and EuCl3 with the aid of CO32− ions derived from atmospheric CO2 affording an unusual heteropolynuclear cluster [Zn4L4Eu4(CO3)6]·EtOH. In the core of the cluster, four hetero-binuclear [ZnLEu] units linked by six CO32− anions forms a well defined [Zn4Eu4] skeleton with good planarity, which plays an important role in stabilizing the cluster.

Chiral NCN pincer rhodium(III) complexes with bis(imidazolinyl)phenyl ligands were found to be effective catalysts for the allylation of a variety of electronically and structurally diverse aldehydes with allyltributyltin, giving the corresponding optically active homoallylic alcohols in high yields with enantioselectivities of up to 97% ee. These complexes were also applied in the carbonyl–ene reaction of ethyl or methyl trifluoropyruvate with various 2-arylpropenes. With the aid of silver trifluoromethanesulfonate, the pincer rhodium(III) catalysts could catalyze the reaction to provide the corresponding chiral α-hydroxy-α-trifluoromethyl esters in good yields with high stereoselectivities (up to 95% ee).

Studies toward the synthesis and characterization of a cationic NCN pincer platinum(II) aquo complex with a chiral bis(imidazolinyl)phenyl (Phebim) ligand are reported. During these studies, the new symmetrical Phebim-H ligands 1c,d and unsymmetrical hybrid oxazoline–imidazoline ligands 6a–c, as well as the related neutral symmetrical NCN pincer Pt(II) complexes 2b–d and 3a–d and unsymmetrical NCN′ pincers 7a,b and 8c have been isolated and characterized. Despite considerable attempts, only one of the expected cationic chiral NCN pincer Pt(II) complexes (4), which contains water as an exchangeable neutral ligand for the Pt(II) center, was obtained in pure form from the reaction of the neutral Pt–I complex 3a with AgOTf in wet CH2Cl2 at room temperature. In contrast, the cationic Pt(II) pyridine complexes 5a,c could be easily prepared in high yields from the reaction of the neutral Pt–Cl complexes 2a,c with AgOTf in the presence of pyridine in CH2Cl2 at room temperature. The molecular structures of the neutral symmetrical Pt(II) complexes 2c,d and 3c,d and the unsymmetrical Pt(II) complex 7b as well as the cationic Pt(II) aquo complex 4 have been determined by X-ray single-crystal analysis. The cationic complexes 4 and 5a,c have been applied to the asymmetric Friedel–Crafts alkylation of indoles with nitroalkenes. Among them, the aquo complex 4 was found to be effective under the given reaction conditions. With a catalyst loading of 5 mol %, a variety of the nitroalkylated indoles were produced in good yields with moderate to good enantioselectivities (up to 83% ee).

Chiral 1,3-bis(2′-imidazolinyl)benzenes 1a–e easily undergo direct nickelation at the C2 position of the central benzene ringvia the C–H bond activation in the reaction with anhydrous NiCl2 giving neutral NCN pincer nickel(II) complexes 2a–e in 40–87% yields. Treatment of the nickel pincers 2a or 2c with AgBF4 in CH3CN–CH2Cl2 afforded the cationic nickel pincers 3a or 3c in good yields. All the complexes were characterized by elemental analysis, 1H, 13C NMR, and IR spectra. Molecular structures of the neutral complexes 2a, 2b and 2c as well as the cationic complex 3c have been determined by X-ray single-crystal diffraction. The cationic nickel pincers 3 are found to be effective catalysts for the Michael addition of ethyl 2-cyanopropionate to methyl vinyl ketone in the presence of i-Pr2NEt base with a catalyst loading of 5 mol% even at −78 °C, producing the adduct in >99% yield after 24 h albeit with no ee.

N-substituted-2-aminomethyl-6-phenylpyridines 2a–c have been easily prepared from commercially available 6-bromo-2-picolinaldehyde in two steps. Reaction of 2a–c with PdCl2 in toluene in the presence of triethylamine gave the CNN pincer Pd(II) complexes 3a–c in 18-28% yields. The CNN pincer Ru(II) complex 5 containing a Ru-NHR functionality could be obtained in a 71% yield by treatment of 2c with a Ru(II) precursor instead of PdCl2. Additionally, the related CNN pincer Ru(II) complex 7 containing a Ru–NH2 functionality has been synthesized by the reaction of 2-aminomethyl-6-phenylpyridine with the same Ru(II) precursor in a 68% yield. All the new compounds were characterized by elemental analysis (MS for ligands), 1H, 13C NMR, 31P{1H} NMR (for Ru complexes) and IR spectra. Molecular structures of Pd complex 3c as well as Ru complexes 5 and 7 have been determined by X-ray single-crystal diffraction. The obtained Pd complexes 3a–c were effective catalysts for the allylation of aldehydes as well as for three-component allylation of aldehydes, arylamines and allyltributyltin and their activity was found to be much higher than a related NCN Pd(II) pincer in the allylation of aldehyde. On the other hand, the two new CNN pincer Ru(II) complexes 5 and 7 displayed excellent catalytic activity in the transfer hydrogenation of ketones in refluxing 2-propanol with the latter being much more active. The final TOF values were up to 4510 h−1 with 0.01 mol% of 5 and 220800 h−1 with 0.005 mol% of 7, respectively.

Chiral 3-(2′-imidazolinyl)anilines 3a–c were easily synthesized by converting the carboxyl and nitro groups in commercially available 3-nitrobenzoic acid to chiral imidazoline and amine, respectively. The one-pot phosphorylation/metalation reaction of 3-(2′-imidazolinyl)anilines 3a–c, where the amino group in 3a–c was first phosphorylated by reaction with PPh2Cl, followed by metalation with PdCl2 or anhydrous NiCl2 in situ, afforded the three unsymmetrical chiral PCN pincer Pd(II) complexes 4a–c and the Ni(II) complex 5a with aryl-based aminophosphine–imidazoline ligands via aryl C–H bond activation of the related ligands. All of the new compounds were characterized by elemental analysis (HRMS for ligand precursors), 1H and 13C NMR, 31P{1H} NMR (for pincer complexes), and IR spectra. The molecular structures of Pd complexes 4a,c and that of Ni complex 5a have been determined by X-ray single-crystal diffraction. Each complex adopts a typical distorted-square-planar geometry. The potential of the obtained chiral pincers in the asymmetric addition of diarylphosphines to β-substituted enones or trans-β-nitrostyrene was investigated. The Pd pincer 4c, the chirality of which originated from l-phenylglycinol, was found to be an effective catalyst for the asymmetric addition of diphenylphosphine to a series of β-aryl enones with high enantioselectivities (12 examples, 51–94% ee's). In particular, excellent yields and enantioselectivities (>90% yields and ≥90% ee's) were obtained when β-aryl groups in the enones bore an electron-withdrawing group such as p-NO2.

An efficient nitrosylation of imidazo[1,2-a]pyridines has been developed using tert-Butyl nitrite (TBN) as the NO resource. The nitrosylation protocol demonstrates broad compatibilities, with various functional groups such as halogen, Me, OMe, COOMe et al. well tolerated. Near quantitative yields could be obtained within the imidazo[1,2-a]pyridine scaffold under the optimized conditions.

Reactions of [Zn(L)(H2O)] precursor and EuCl3 with the aid of CO32− ions derived from atmospheric CO2 affording an unusual heteropolynuclear cluster [Zn4L4Eu4(CO3)6]·EtOH. In the core of the cluster, four hetero-binuclear [ZnLEu] units linked by six CO32− anions forms a well defined [Zn4Eu4] skeleton with good planarity, which plays an important role in stabilizing the cluster.

N-substituted-2-aminomethyl-6-phenylpyridines 2a–c have been easily prepared from commercially available 6-bromo-2-picolinaldehyde in two steps. Reaction of 2a–c with PdCl2 in toluene in the presence of triethylamine gave the CNN pincer Pd(II) complexes 3a–c in 18-28% yields. The CNN pincer Ru(II) complex 5 containing a Ru-NHR functionality could be obtained in a 71% yield by treatment of 2c with a Ru(II) precursor instead of PdCl2. Additionally, the related CNN pincer Ru(II) complex 7 containing a Ru–NH2 functionality has been synthesized by the reaction of 2-aminomethyl-6-phenylpyridine with the same Ru(II) precursor in a 68% yield. All the new compounds were characterized by elemental analysis (MS for ligands), 1H, 13C NMR, 31P{1H} NMR (for Ru complexes) and IR spectra. Molecular structures of Pd complex 3c as well as Ru complexes 5 and 7 have been determined by X-ray single-crystal diffraction. The obtained Pd complexes 3a–c were effective catalysts for the allylation of aldehydes as well as for three-component allylation of aldehydes, arylamines and allyltributyltin and their activity was found to be much higher than a related NCN Pd(II) pincer in the allylation of aldehyde. On the other hand, the two new CNN pincer Ru(II) complexes 5 and 7 displayed excellent catalytic activity in the transfer hydrogenation of ketones in refluxing 2-propanol with the latter being much more active. The final TOF values were up to 4510 h−1 with 0.01 mol% of 5 and 220800 h−1 with 0.005 mol% of 7, respectively.

The (ppy)-based Pt(II) complex (Pt-1) with deprotonated 2-(diphenylphosphino)benzoic acid as an anionic ligand displays phosphorescence of monomers with a remarkably higher quantum yield than that of the corresponding iridium complex (Ir-1). A prototype OLED using Pt-1 exhibits high performance with an external quantum efficiency of 4.93%.

By using a robust acenaphthoimidazolylidene palladium complex (Pd-NHC 1), a scalable approach to access a variety of chiral, pharmaceutical and structurally intriguing N-substituted phthalimides via double aminocarbonylations has been established under atmospheric carbon monoxide pressure at catalyst loadings as low as 0.05 mol%. In addition, the fluorescent properties of the selected N-substituted phthalimide products were also characterized. In comparison with well-known fluorescent molecules, some of them exhibited enhanced violet emission, especially for the ester analogue of Alrestatin, which further confirmed the applicability of the protocol.

A series of chiral (imidazoline–oxazoline) N,N-bidentate ligands L1–L5 derived from 2,2-dimethylmalonic acid were conveniently synthesized and characterized. With the aid of the new ligands, the first Co(II)-catalyzed asymmetric Michael addition of 2-acetyl azaarenes to β-CF3-β-disubstituted nitroalkenes was successfully achieved, producing chiral compounds with a trifluoromethylated all-carbon quaternary stereocenter in good yields with enantioselectivities of up to 98% ee.

Chiral 1,3-bis(2′-imidazolinyl)benzenes 1a–e easily undergo direct nickelation at the C2 position of the central benzene ringvia the C–H bond activation in the reaction with anhydrous NiCl2 giving neutral NCN pincer nickel(II) complexes 2a–e in 40–87% yields. Treatment of the nickel pincers 2a or 2c with AgBF4 in CH3CN–CH2Cl2 afforded the cationic nickel pincers 3a or 3c in good yields. All the complexes were characterized by elemental analysis, 1H, 13C NMR, and IR spectra. Molecular structures of the neutral complexes 2a, 2b and 2c as well as the cationic complex 3c have been determined by X-ray single-crystal diffraction. The cationic nickel pincers 3 are found to be effective catalysts for the Michael addition of ethyl 2-cyanopropionate to methyl vinyl ketone in the presence of i-Pr2NEt base with a catalyst loading of 5 mol% even at −78 °C, producing the adduct in >99% yield after 24 h albeit with no ee.