Steric Hindrance in a Mixed Solvated Nickel(II) Complex: Bis(acetonitrile-N)tetrakis(N,N-dimethylacetamide-O)nickel(II) Bis(tetrafluoroborate)

The title compound, [Ni(CH₃CN)₂{(CH₃)₂NCOCH₃}₄](BF₄)₂, has an octahedral coordination structure with the centre of symmetry at the Ni atom. Both of the two crystallographically inequivalent N,N-dimethylacetamide (DMA) molecules have normal coordination bond lengths Ni-O and angles Ni-O-C, but one of the Ni-O-C-N torsion angles deviates from 180°, indicating that the Ni-O bond is displaced from the direction of the lone pair of the sp² O atom. It is ascribed to the steric hindrance of DMA coordination in an octahedral environment, which is imposed by the non-bonding contact of the acetyl methyl group with the ligating oxygen atom of the adjacent DMA molecule.

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