Structure and magnetic property of a mixed-valence nonanuclear cobalt compound with a square-pyramidal Co^II₅ core

A novel cobalt compound [Co₉(HL)₄(L) ₄Cl₂]·(EtOH)₂(H₂O) ₂ (H₃L = (E)-2-2((1,3-dihydroxy-2-methylpropan-2-ylimino) methyl) phenol) has been solvothermally synthesized and structurally characterized. The compound crystallised in the space group C2/c with a = 32.624(2) Å, b = 9.4814(4) Å, c = 33.395(2) Å, β = 109.339(5)° and V = 9746.8(9) ų. The crystal structure is a mixed-valence nonanuclear Co(II/III) oligomer, which contains a square-pyramidal Co^II₅ core formed through μ₄-Cl and μ₃-alkoxo bridges and the pentanuclear Co^II₅ core is surrounded by four peripheral Co(III) ions at the square-pyramidal base plane through μ₂-alkoxo bridges. Magnetic properties of the compound can be considered as the magnetism of the Co^II₅ core, and the superexchange interactions between Co(II) ions within the core were calculated with three Co(II)-Co(II) superexchange parameters by using MAGPACK software package to give J₁ = + 11.1 cm^-1, J₂ = -6.50 cm^-1, J₃ = -3.25 cm^-1, D = + 6.0 cm^-1 and g = 2.30.