A series of cobalt and nickel clusters based on thiol-containing ligands accompanied by in situ ligand formation

Abstract

Eight cobalt and nickel clusters with the formulae [Co₄(μ₄-O)(MBT)₅(μ₂-Piv)] (1), [Ni₃(MBT)₂(L1)₂(OCH₃)₂] (2), [Ni₄(μ₃-S)(μ₃-S₂)(MBT)₂(L2)] (3), [Ni₄(L3)₄] (4), [Ni₆(μ₄-S)₃(MBT)₆]·(C₂H₅OH)₂ (5), H[Co₄(μ₄-O)(HMBI)₆]·(NO₃)(TEA)_0.5(CH₃OH)₂(H₂O) (6), [Ni₂(HMBI)₄]·(CH₃OH)₂ (7), and [Ni₅(MBI)₂(HMBI)₄(OCH₃)₂]·(CH₃OH)₃(H₂O)₂ (8) (HPiv = pivalic acid, HL1 = 2-disulfanylbenzo[d]thiazole, H₂L2 = (Z)-2-((2-mercaptophenyl)imino)benzo[d]thiazole-3(2H)-thiol, H₂L3 = (Z)-2-(benzo[d]thiazol-2(3H)-ylideneamino)benzenethiol, TEA = triethylamine) have been solvothermally prepared via assembling distinct metal resource and thiol-containing ligands 2-mercaptobenzothiazole (HMBT)/2-mercaptobenzimidazole (H₂MBI). Complexes 1 and 6 are tetrahedral cobalt clusters. Complex 2 features linear arrangement of nickel ions. Complexes 3 and 4 are tetranuclear nickel clusters with the butterfly and square shape, respectively. Complex 5 displays a trigonal prism geometry. Complexes 7 and 8 exhibit paddle-wheel and trigonal bipyramidal geometry, respectively. The starting ligand HMBT undergoes in situ ligand transformation in the formation of the nickel clusters, and the new generated inorganic ligands (S²⁻ and S₂²⁻) and organic ligands (HL1, H₂L2 and H₂L3) were captured within the metallic cores. Magnetic studies indicate that complexes 1 and 6 show dominating antiferromagnetic couplings and that spin frustration exists in 6.