The synthesis and magnetic properties of the compounds [HNEt3][Fe2(OMe)(Ph-sao)2 (Ph-saoH)2]·5MeOH (1·5MeOH), [Fe3O(Et-sao)(O2CPh)5(MeOH)2]·3MeOH (2·3MeOH), [Fe4(Me-sao)4(Me-saoH)4] (3), [HNEt3]2[Fe6O2(Me-sao)4(SO4)2(OMe)4(MeOH)2] (4), [Fe8O3(Me-sao)3(tea)(teaH)3(O2CMe)3] (5), [Fe8O3(Et-sao)3(tea)(teaH)3(O2CMe)3] (6), and [Fe8O3(Ph-sao)3(tea)(teaH)3(O2CMe)3] (7) are reported (Me-saoH2 is 2′-hydroxyacetophenone oxime, Et-saoH2 is 2′-hydroxypropiophenone oxime and Ph-saoH2 is 2-hydroxybenzophenone oxime). 1–7 are the first FeIII compounds synthesised using the derivatised salicylaldoxime ligands, R-saoH2. 1 is prepared by treatment of Fe2(SO4)3·6H2O with Ph-saoH2 in the presence of NEt3 in MeOH; 2 prepared by treatment of Fe(ClO4)2·6H2O with Et-saoH2 and NaO2CPh in the presence of NEt4OH in MeOH; 3 prepared by treatment of Fe(ClO4)2·6H2O with Me-saoH2 and NaO2CCMe3 in the presence of NEt4OH in MeOH; and 4 prepared by treatment of Fe2(SO4)3·6H2O with Me-saoH2 in the presence of NEt3 in MeOH. 4 is a rare example of a polynuclear iron complex containing a coordinated SO42− ion. Compounds 5–7 are prepared by treatment of Fe(O2CMe)2 with Me-saoH2 (5), Et-saoH2 (6), Ph-saoH2 (7) in the presence of H3tea (triethanolamine) in MeOH, and represent the largest nuclearity FeIII clusters containing salicyladoxime-based ligands, joining a surprisingly small family of characterised octanuclear Fe complexes. Variable temperature magnetic susceptibilty measurements of 1,3 and 5–7 reveal all five complexes possess S = 0 spin ground states; 2 possesses an S = 1/2 spin ground state, while 4 has an S = 4 ± 1 spin ground state.

The synthesis and magnetic properties of the compounds [HNEt3][Fe2(OMe)(Ph-sao)2 (Ph-saoH)2]·5MeOH (1·5MeOH), [Fe3O(Et-sao)(O2CPh)5(MeOH)2]·3MeOH (2·3MeOH), [Fe4(Me-sao)4(Me-saoH)4] (3), [HNEt3]2[Fe6O2(Me-sao)4(SO4)2(OMe)4(MeOH)2] (4), [Fe8O3(Me-sao)3(tea)(teaH)3(O2CMe)3] (5), [Fe8O3(Et-sao)3(tea)(teaH)3(O2CMe)3] (6), and [Fe8O3(Ph-sao)3(tea)(teaH)3(O2CMe)3] (7) are reported (Me-saoH2 is 2′-hydroxyacetophenone oxime, Et-saoH2 is 2′-hydroxypropiophenone oxime and Ph-saoH2 is 2-hydroxybenzophenone oxime). 1–7 are the first FeIII compounds synthesised using the derivatised salicylaldoxime ligands, R-saoH2. 1 is prepared by treatment of Fe2(SO4)3·6H2O with Ph-saoH2 in the presence of NEt3 in MeOH; 2 prepared by treatment of Fe(ClO4)2·6H2O with Et-saoH2 and NaO2CPh in the presence of NEt4OH in MeOH; 3 prepared by treatment of Fe(ClO4)2·6H2O with Me-saoH2 and NaO2CCMe3 in the presence of NEt4OH in MeOH; and 4 prepared by treatment of Fe2(SO4)3·6H2O with Me-saoH2 in the presence of NEt3 in MeOH. 4 is a rare example of a polynuclear iron complex containing a coordinated SO42− ion. Compounds 5–7 are prepared by treatment of Fe(O2CMe)2 with Me-saoH2 (5), Et-saoH2 (6), Ph-saoH2 (7) in the presence of H3tea (triethanolamine) in MeOH, and represent the largest nuclearity FeIII clusters containing salicyladoxime-based ligands, joining a surprisingly small family of characterised octanuclear Fe complexes. Variable temperature magnetic susceptibilty measurements of 1,3 and 5–7 reveal all five complexes possess S = 0 spin ground states; 2 possesses an S = 1/2 spin ground state, while 4 has an S = 4 ± 1 spin ground state.

The synthesis and characterisation of a large family of trimetallic [MnIII3] Single-Molecule Magnets is presented. The complexes reported can be divided into three categories with general formulae (type 1) [MnIII3O(R-sao)3(X)(sol)3-4] (where R = H, Me, tBu; X = −O2CR (R = H, Me, Ph etc); sol = py and/or H2O), (type 2) [MnIII3O(R-sao)3(X)(sol)3-5] (where R = Me, Et, Ph, tBu; X = −O2CR (R = H, Me, Ph etc); sol = MeOH, EtOH and/or H2O), and (type 3) [MnIII3O(R-sao)3(sol)3(XO4)] (where R = H, Et, Ph, naphth; sol = py, MeOH, β-pic, Et-py, tBu-py; X = Cl, Re). We show that deliberate structural distortions of the molecule can be used to tune the observed magnetic properties. In the crystals the ferromagnetic triangles are involved in extensive inter-molecular H-bonding which is clearly manifested in the magnetic behaviour, producing exchange-biased SMMs. These interactions can be removed by ligand replacement to give “simpler” SMMs.

The synthesis and characterisation of a large family of trimetallic [MnIII3] Single-Molecule Magnets is presented. The complexes reported can be divided into three categories with general formulae (type 1) [MnIII3O(R-sao)3(X)(sol)3-4] (where R = H, Me, tBu; X = −O2CR (R = H, Me, Ph etc); sol = py and/or H2O), (type 2) [MnIII3O(R-sao)3(X)(sol)3-5] (where R = Me, Et, Ph, tBu; X = −O2CR (R = H, Me, Ph etc); sol = MeOH, EtOH and/or H2O), and (type 3) [MnIII3O(R-sao)3(sol)3(XO4)] (where R = H, Et, Ph, naphth; sol = py, MeOH, β-pic, Et-py, tBu-py; X = Cl, Re). We show that deliberate structural distortions of the molecule can be used to tune the observed magnetic properties. In the crystals the ferromagnetic triangles are involved in extensive inter-molecular H-bonding which is clearly manifested in the magnetic behaviour, producing exchange-biased SMMs. These interactions can be removed by ligand replacement to give “simpler” SMMs.

The syntheses, structures and magnetic properties of nine new iron complexes containing salicylaldoxime (saoH2) or derivatised salicylaldoximes (R-saoH2), [Fe3O(OMe)(Ph-sao)2 Cl2(py)3]·2MeOH (1·2MeOH), [Fe3O(OMe)(Ph-sao)2Br2(py)3]·Et2O (2·Et2O), [Fe4(Ph-sao)4F4(py)4]·1.5MeOH (3·1.5MeOH), [Fe6O2(OH)2(Et-sao)2(Et-saoH)2(O2CPh)6] (4), [HNEt3]2[Fe6O2(OH)2(Et-sao)4(O2CPh(Me)2)6]·2MeCN (5·2MeCN), [Fe6O2(O2CPh)10(3-tBut-5-NO2-sao)2(H2O)2]·2MeCN (6·2MeCN), [Fe6O2(O2CCH2Ph)10(3-tBut-sao)2(H2O)2]·5MeCN (7·5MeCN), {[Fe6Na3O(OH)4(Me-sao)6(OMe)3(H2O)3(MeOH)6]·MeOH}n (8·MeOH) and [HNEt3]2[Fe12Na4O2(OH)8(sao)12(OMe)6(MeOH)10] (9) are discussed. The predominant building block appears to be the triangular [Fe3O(R-sao)3]+ species which can self-assemble into more elaborate arrays depending on reaction conditions. An interesting observation is that the R-saoH−/R-sao2− ligand system tends to adopt coordination modes similar to carboxylates. The most unusual molecule is the [Fe4F4] molecular square, 3. While Cl− and Br− appear to act only as terminal ligands, the F− ions bridge making a telling impact on molecular structure and topology.

The syntheses, structures and magnetic properties of nine new iron complexes containing salicylaldoxime (saoH2) or derivatised salicylaldoximes (R-saoH2), [Fe3O(OMe)(Ph-sao)2 Cl2(py)3]·2MeOH (1·2MeOH), [Fe3O(OMe)(Ph-sao)2Br2(py)3]·Et2O (2·Et2O), [Fe4(Ph-sao)4F4(py)4]·1.5MeOH (3·1.5MeOH), [Fe6O2(OH)2(Et-sao)2(Et-saoH)2(O2CPh)6] (4), [HNEt3]2[Fe6O2(OH)2(Et-sao)4(O2CPh(Me)2)6]·2MeCN (5·2MeCN), [Fe6O2(O2CPh)10(3-tBut-5-NO2-sao)2(H2O)2]·2MeCN (6·2MeCN), [Fe6O2(O2CCH2Ph)10(3-tBut-sao)2(H2O)2]·5MeCN (7·5MeCN), {[Fe6Na3O(OH)4(Me-sao)6(OMe)3(H2O)3(MeOH)6]·MeOH}n (8·MeOH) and [HNEt3]2[Fe12Na4O2(OH)8(sao)12(OMe)6(MeOH)10] (9) are discussed. The predominant building block appears to be the triangular [Fe3O(R-sao)3]+ species which can self-assemble into more elaborate arrays depending on reaction conditions. An interesting observation is that the R-saoH−/R-sao2− ligand system tends to adopt coordination modes similar to carboxylates. The most unusual molecule is the [Fe4F4] molecular square, 3. While Cl− and Br− appear to act only as terminal ligands, the F− ions bridge making a telling impact on molecular structure and topology.

A new family of hexametallic [MnIII6] Single-Molecule Magnets with general formula [Mn6O2(R-sao)6(X)2(MeOH)4-6] (R = H, Me, Et or Ph; X = O2PHPh or O2P(Ph)2) have been synthesised and characterised. The molecules are new members of the [Mn6] family of SMMs in which the carboxylate ligands have been replaced with phenyl- and diphenylphosphinate. The magnetic cores remain largely unaltered meaning that structural distortions of the Mn–N–O–Mn torsion angles in the [Mn3O] subunits can be used to tune the magnetic properties, switching pairwise exchange interactions from antiferromagnetic to ferromagnetic. The results suggest that the Mn6 building block, be it ferro- or antiferromagnetically coupled, could be an important building block for the formation of novel, functional 0-3D materials.

A new family of hexametallic [MnIII6] Single-Molecule Magnets with general formula [Mn6O2(R-sao)6(X)2(MeOH)4-6] (R = H, Me, Et or Ph; X = O2PHPh or O2P(Ph)2) have been synthesised and characterised. The molecules are new members of the [Mn6] family of SMMs in which the carboxylate ligands have been replaced with phenyl- and diphenylphosphinate. The magnetic cores remain largely unaltered meaning that structural distortions of the Mn–N–O–Mn torsion angles in the [Mn3O] subunits can be used to tune the magnetic properties, switching pairwise exchange interactions from antiferromagnetic to ferromagnetic. The results suggest that the Mn6 building block, be it ferro- or antiferromagnetically coupled, could be an important building block for the formation of novel, functional 0-3D materials.

The reaction of Mn(ClO4)2·6H2O with Ph-saoH2 (Ph-saoH2 = 2-hydroxybenzophenone oxime) in MeCN in the presence of sodium propionate forms the complex [MnIII6O2(Ph-sao)6(prop)2(MeCN)2]·5.27MeCN (1·5.27MeCN) (prop = propionate). Repeating the same reaction in EtOH produces the complex [MnIII6O2(Ph-sao)6(prop)2(EtOH)4] (2). Complexes 1 and 2 may be considered as structural isomers, since they display the same metallic core but different coordination modes of the propionate ligands; bridging in 1 and terminal in 2. Performing similar reactions and switching from sodium propionate to sodium adamantane-carboxylate (NaO2C-ada) and sodium pivalate (Napiv) in the presence of NEt4OH yields the complexes [MnIII6O2(Ph-sao)6(O2C-ada)2(MeOH)4] (3) and [MnIII6O2(Ph-sao)6(piv)2(EtOH)4]·0.5Et2O (4·0.5Et2O), respectively. All four complexes contain the same {MnIII3O(Ph-sao)3} building block. Variable temperature magnetic susceptibility and magnetization studies show that all complexes possess an S = 4 ground-state.

The reaction of Mn(ClO4)2·6H2O with Ph-saoH2 (Ph-saoH2 = 2-hydroxybenzophenone oxime) in MeCN in the presence of sodium propionate forms the complex [MnIII6O2(Ph-sao)6(prop)2(MeCN)2]·5.27MeCN (1·5.27MeCN) (prop = propionate). Repeating the same reaction in EtOH produces the complex [MnIII6O2(Ph-sao)6(prop)2(EtOH)4] (2). Complexes 1 and 2 may be considered as structural isomers, since they display the same metallic core but different coordination modes of the propionate ligands; bridging in 1 and terminal in 2. Performing similar reactions and switching from sodium propionate to sodium adamantane-carboxylate (NaO2C-ada) and sodium pivalate (Napiv) in the presence of NEt4OH yields the complexes [MnIII6O2(Ph-sao)6(O2C-ada)2(MeOH)4] (3) and [MnIII6O2(Ph-sao)6(piv)2(EtOH)4]·0.5Et2O (4·0.5Et2O), respectively. All four complexes contain the same {MnIII3O(Ph-sao)3} building block. Variable temperature magnetic susceptibility and magnetization studies show that all complexes possess an S = 4 ground-state.

The serendipitous self-assembly of the complex [MnIII2ZnII2(Ph-sao)2(Ph-saoH)4(hmp)2] (1),whose magnetic core consists solely of two symmetry equivalent Mn(III) ions linked by two symmetry equivalent –N–O– moieties, provides a relatively simple model complex with which to study the magneto-structural relationship in oxime-bridged Mn(III) cluster compounds. Dc magnetic susceptibility measurements reveal ferromagnetic (J = +2.2 cm−1) exchange resulting in an S = 4 ground state. Magnetisation measurements performed at low temperatures and high fields reveal the presence of significant anisotropy, with ac measurements confirming slow relaxation of the magnetisation and Single-Molecule Magnetism behaviour. Simulations of high field, high frequency EPR data reveal a single ion anisotropy, D(MnIII) = −3.83 cm−1. DFT studies on a simplified model complex of 1 reveal a pronounced dependence of the exchange coupling on the relative twisting of the oxime moiety with respect to the metal ion positions, as suggested previously in more complicated [MnIII3] and [MnIII6] clusters.

The serendipitous self-assembly of the complex [MnIII2ZnII2(Ph-sao)2(Ph-saoH)4(hmp)2] (1),whose magnetic core consists solely of two symmetry equivalent Mn(III) ions linked by two symmetry equivalent –N–O– moieties, provides a relatively simple model complex with which to study the magneto-structural relationship in oxime-bridged Mn(III) cluster compounds. Dc magnetic susceptibility measurements reveal ferromagnetic (J = +2.2 cm−1) exchange resulting in an S = 4 ground state. Magnetisation measurements performed at low temperatures and high fields reveal the presence of significant anisotropy, with ac measurements confirming slow relaxation of the magnetisation and Single-Molecule Magnetism behaviour. Simulations of high field, high frequency EPR data reveal a single ion anisotropy, D(MnIII) = −3.83 cm−1. DFT studies on a simplified model complex of 1 reveal a pronounced dependence of the exchange coupling on the relative twisting of the oxime moiety with respect to the metal ion positions, as suggested previously in more complicated [MnIII3] and [MnIII6] clusters.

A combination of complementary ligands, p-tert-butylcalix[8]arene (TBC[8]) and phenyl salicylaldoxime (Ph-saoH2) have been utilised in the facile synthesis of a MnIIIMnIV dimer. Magnetic measurements reveal ferromagnetic exchange between the two metal ions.

A combination of complementary ligands, p-tert-butylcalix[8]arene (TBC[8]) and phenyl salicylaldoxime (Ph-saoH2) have been utilised in the facile synthesis of a MnIIIMnIV dimer. Magnetic measurements reveal ferromagnetic exchange between the two metal ions.

The reaction of Mn(ClO4)2·6H2O, a derivatised phenolic oxime (R-saoH2) and the ligand tris(2-pyridylmethyl)amine (tpa) in a basic alcoholic solution leads to the formation of a family of cluster compounds of general formula [MnIII2O(R-sao)(tpa)2](ClO4)2 (1, R = H; 2, R = Me; 3, R = Et; 4, R = Ph). The structure is that of a simple, albeit asymmetric, dimer of two MnIII ions bridged through one μ-O2− ion and the –N–O– moiety of the phenolic oxime. Magnetometry reveals that the exchange interaction between the two MnIII ions in complexes 1, 3 and 4 is antiferromagnetic, but that for complex 2 is ferromagnetic. A theoretically developed magneto-structural correlation reveals that the dominant structural parameter influencing the sign and magnitude of the pairwise interaction is the dihedral Mn–O–N–Mn (torsion) angle. A linear correlation is found, with the magnitude of J varying significantly as the dihedral angle is altered. As the torsion angle increases the AF exchange decreases, matching the experimentally determined data. DFT calculations reveal that the dyz|π*|dyz interaction decreases as the dihedral angle increases leading to ferromagnetic coupling at larger angles.

The reaction of Mn(ClO4)2·6H2O, a derivatised phenolic oxime (R-saoH2) and the ligand tris(2-pyridylmethyl)amine (tpa) in a basic alcoholic solution leads to the formation of a family of cluster compounds of general formula [MnIII2O(R-sao)(tpa)2](ClO4)2 (1, R = H; 2, R = Me; 3, R = Et; 4, R = Ph). The structure is that of a simple, albeit asymmetric, dimer of two MnIII ions bridged through one μ-O2− ion and the –N–O– moiety of the phenolic oxime. Magnetometry reveals that the exchange interaction between the two MnIII ions in complexes 1, 3 and 4 is antiferromagnetic, but that for complex 2 is ferromagnetic. A theoretically developed magneto-structural correlation reveals that the dominant structural parameter influencing the sign and magnitude of the pairwise interaction is the dihedral Mn–O–N–Mn (torsion) angle. A linear correlation is found, with the magnitude of J varying significantly as the dihedral angle is altered. As the torsion angle increases the AF exchange decreases, matching the experimentally determined data. DFT calculations reveal that the dyz|π*|dyz interaction decreases as the dihedral angle increases leading to ferromagnetic coupling at larger angles.

The syntheses, structures and magnetic properties of nine new iron complexes containing salicylaldoxime (saoH2) or derivatised salicylaldoximes (R-saoH2), [Fe3O(OMe)(Ph-sao)2 Cl2(py)3]·2MeOH (1·2MeOH), [Fe3O(OMe)(Ph-sao)2Br2(py)3]·Et2O (2·Et2O), [Fe4(Ph-sao)4F4(py)4]·1.5MeOH (3·1.5MeOH), [Fe6O2(OH)2(Et-sao)2(Et-saoH)2(O2CPh)6] (4), [HNEt3]2[Fe6O2(OH)2(Et-sao)4(O2CPh(Me)2)6]·2MeCN (5·2MeCN), [Fe6O2(O2CPh)10(3-tBut-5-NO2-sao)2(H2O)2]·2MeCN (6·2MeCN), [Fe6O2(O2CCH2Ph)10(3-tBut-sao)2(H2O)2]·5MeCN (7·5MeCN), {[Fe6Na3O(OH)4(Me-sao)6(OMe)3(H2O)3(MeOH)6]·MeOH}n (8·MeOH) and [HNEt3]2[Fe12Na4O2(OH)8(sao)12(OMe)6(MeOH)10] (9) are discussed. The predominant building block appears to be the triangular [Fe3O(R-sao)3]+ species which can self-assemble into more elaborate arrays depending on reaction conditions. An interesting observation is that the R-saoH−/R-sao2− ligand system tends to adopt coordination modes similar to carboxylates. The most unusual molecule is the [Fe4F4] molecular square, 3. While Cl− and Br− appear to act only as terminal ligands, the F− ions bridge making a telling impact on molecular structure and topology.

The syntheses, structures and magnetic properties of nine new iron complexes containing salicylaldoxime (saoH2) or derivatised salicylaldoximes (R-saoH2), [Fe3O(OMe)(Ph-sao)2 Cl2(py)3]·2MeOH (1·2MeOH), [Fe3O(OMe)(Ph-sao)2Br2(py)3]·Et2O (2·Et2O), [Fe4(Ph-sao)4F4(py)4]·1.5MeOH (3·1.5MeOH), [Fe6O2(OH)2(Et-sao)2(Et-saoH)2(O2CPh)6] (4), [HNEt3]2[Fe6O2(OH)2(Et-sao)4(O2CPh(Me)2)6]·2MeCN (5·2MeCN), [Fe6O2(O2CPh)10(3-tBut-5-NO2-sao)2(H2O)2]·2MeCN (6·2MeCN), [Fe6O2(O2CCH2Ph)10(3-tBut-sao)2(H2O)2]·5MeCN (7·5MeCN), {[Fe6Na3O(OH)4(Me-sao)6(OMe)3(H2O)3(MeOH)6]·MeOH}n (8·MeOH) and [HNEt3]2[Fe12Na4O2(OH)8(sao)12(OMe)6(MeOH)10] (9) are discussed. The predominant building block appears to be the triangular [Fe3O(R-sao)3]+ species which can self-assemble into more elaborate arrays depending on reaction conditions. An interesting observation is that the R-saoH−/R-sao2− ligand system tends to adopt coordination modes similar to carboxylates. The most unusual molecule is the [Fe4F4] molecular square, 3. While Cl− and Br− appear to act only as terminal ligands, the F− ions bridge making a telling impact on molecular structure and topology.

The reaction of Mn(ClO4)2·6H2O with Ph-saoH2 (Ph-saoH2 = 2-hydroxybenzophenone oxime) in MeCN in the presence of sodium propionate forms the complex [MnIII6O2(Ph-sao)6(prop)2(MeCN)2]·5.27MeCN (1·5.27MeCN) (prop = propionate). Repeating the same reaction in EtOH produces the complex [MnIII6O2(Ph-sao)6(prop)2(EtOH)4] (2). Complexes 1 and 2 may be considered as structural isomers, since they display the same metallic core but different coordination modes of the propionate ligands; bridging in 1 and terminal in 2. Performing similar reactions and switching from sodium propionate to sodium adamantane-carboxylate (NaO2C-ada) and sodium pivalate (Napiv) in the presence of NEt4OH yields the complexes [MnIII6O2(Ph-sao)6(O2C-ada)2(MeOH)4] (3) and [MnIII6O2(Ph-sao)6(piv)2(EtOH)4]·0.5Et2O (4·0.5Et2O), respectively. All four complexes contain the same {MnIII3O(Ph-sao)3} building block. Variable temperature magnetic susceptibility and magnetization studies show that all complexes possess an S = 4 ground-state.

The reaction of Mn(ClO4)2·6H2O with Ph-saoH2 (Ph-saoH2 = 2-hydroxybenzophenone oxime) in MeCN in the presence of sodium propionate forms the complex [MnIII6O2(Ph-sao)6(prop)2(MeCN)2]·5.27MeCN (1·5.27MeCN) (prop = propionate). Repeating the same reaction in EtOH produces the complex [MnIII6O2(Ph-sao)6(prop)2(EtOH)4] (2). Complexes 1 and 2 may be considered as structural isomers, since they display the same metallic core but different coordination modes of the propionate ligands; bridging in 1 and terminal in 2. Performing similar reactions and switching from sodium propionate to sodium adamantane-carboxylate (NaO2C-ada) and sodium pivalate (Napiv) in the presence of NEt4OH yields the complexes [MnIII6O2(Ph-sao)6(O2C-ada)2(MeOH)4] (3) and [MnIII6O2(Ph-sao)6(piv)2(EtOH)4]·0.5Et2O (4·0.5Et2O), respectively. All four complexes contain the same {MnIII3O(Ph-sao)3} building block. Variable temperature magnetic susceptibility and magnetization studies show that all complexes possess an S = 4 ground-state.