Use of the sulfato ligand in 3d-metal cluster chemistry: A family of hexanuclear nickel(II) complexes with 2-pyridyl-substituted oxime ligands

Abstract

The initial use of 2-pyridyl-substituted oximes [(py)C(R)-NOH

R = Me, Ph]/sulfate blend in nickel(II) chemistry has yielded a family of hexanuclear clusters. The syntheses, structures and magnetic properties are reported of [Ni6(SO4)4-(OH){(py)C(Me)NO} 3{(py)C(Me)NOH}3(MeOH)2(H2O)] (1), [Ni6(SO4)4(OH){(py)C(ph)NO}3{(py) C(ph)NOH}3(MeOH)3] (2) and [Ni6(SO 4)4(OH){(py)C(ph)NO}3{(py)C(ph)NOH} 3(H2O)3] (3), where (py)C(Me)NOH is methyl 2-pyridyl ketone oxime and (py)C(ph)NOH is phenyl 2-pyridyl ketone oxime. The hexanuclear molecules present in the three complexes have similar structures which contain the [Ni6(μ3-OH)(μ3-SO 4)3(μ3-ONR)3]2+ core. The core consists of six NiII ions arranged as two parallel equilateral triangular subunits, one small (Ni⋯Ni ca. 3.3 Å) and the other larger (Ni⋯Ni ca. 6.0 Å). Characteristic IR bands are discussed in terms of the known structures of 1-3. The magnetic properties of 1 and 2 have been studied by variable-temperature dc magnetic susceptibility techniques which indicate antiferromagnetic interactions. A simple 2-J model was found to be adequate to describe the similar thermal variation of the molar magnetic susceptibilities of 1 and 2. © Wiley-VCH Verlag GmbH & Co. KGaA, 2007.