Employment of the sulfate ligand in 3d-metal cluster chemistry: A novel hexanuclear nickel(II) complex with a chair metal topology

The preparation and crystal structure of a hexanuclear Ni(II) sulfato cluster containing the anion of phenyl(2-pyridyl)ketone oxime, (py)C(ph)NO−, is reported. Treatment of NiSO4·6H2O with 1 equiv. of (py)C(ph)NOH and 1 equiv. of NaOMe in DMF under reflux leads to the compound [Νi6(SO4)2{(py)C(ph)NO}8]·6DMF (1·6DMF) in moderate yield. The metal ions are linked together by two 3.211 (Harris notation) (py)C(ph)NO− ligands, six 2.111 (py)C(ph)NO− ligands and two 5.2210 SO42- ions. Its skeleton consists of six NiII ions arranged in a chair conformation. Compound 1 joins a small family of structurally characterized metal complexes containing the neutral or anionic forms of phenyl(2-pyridyl)ketone oxime as ligands, and it is a rare example in which the SO42- ions are coordinated in the 5.2210 fashion. Characteristic IR bands are discussed in terms of the known structure of 1. Its magnetic properties have been studied by variable-temperature dc magnetic susceptibility techniques which indicate competitive antiferromagnetic interactions within its triangular subunits.

The reaction of NiSO4·6H2O and phenyl(2-pyridyl)ketone oxime [(py)C(ph)NOH] in DMF in the presence of base has provided access to the novel hexanuclear Ni(II) cluster [Νi6(SO4)2{(py)C(ph)NO}8]·6DMF (1·6DMF) with the chair-like core [Ni6(μ5-SO4)2(μ2-ONR)6(μ3-ONR)2] core; in compound 1 the SO42- adopts the rare 5.2210 coordination mode.Figure optionsDownload as PowerPoint slide