Syntheses, Crystal Structure and Magnetism of a Hexanuclear Copper(II) Cluster With the Unique Two Parallel Three-site Strings Configuration

Treatment of a heptadentate ligand 2,2'-(((pyridine-2,6-diyl-bis(methylene))-bis((pyridin-2-ylmethyl)azanediyl))bis(methylene))diphenol(H2L) possessing pyridinyl and phenolate groups, with three equivalents of Cu(Cl O4)2·6H2O in methanol under base conditions, gave rise to a hexanuclear cluster complex [Cu6L2(OH)4](Cl O4)4·4Me CN·0.5Me OH(1). Complex 1 crystallizes in triclinic, space group P1 with a = 12.068(12), b = 12.567(12), c = 16.279(16) , α = 105.694(12), β = 93.631(13), γ = 112.017(11)o, V = 2166(4) 3, Z = 1, μ = 1.651 mm-1, Dc = 1.599 Mg/m3, T = 296(2) K, C74.5H79.5N14O24.5Cl4Cu6, Mr = 2086.12, F(000) = 1062.5, S = 1.061, R = 0.0521 and w R = 0.1270. In the cation of complex 1, the six copper cores are arranged into a two-parallel three-site strings configuration with each metal exhibits a slightly distorted square-pyramidal geometry, resulting from the connection of donor pyridinyl nitrogen and phenolate oxygen atoms in ligand H2 L, and/or the oxygen donors in hydroxyl groups. In addition, magnetic susceptibility measurements revealed complex 1 displayed antiferromagnetic coupling.