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DOI: 10.1039/A607837K (Paper) Reference Section for: J. Chem. Soc., Dalton Trans., 1997, 1165-1168

Mechanism of formation of heteroleptic nickel(II)–arsine complexes from homoleptic precursors

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David A. Buckingham, Charles R. Clark, Lyall R. Hanton and David A. McMorran

Abstract

The reaction of square-pyramidal [Ni(bdmma)2]2+ {bdmma = bis[2-(dimethylarsino)phenyl]methylarsine } with either free pdma [o-phenylenebis(dimethylarsine)] or square-planar [Ni(pdma)2]2+ gave five-co-ordinate [Ni(bdmma)(pdma)]2+. Kinetic studies (acidified 5% aqueous acetonitrile, 25.0 °C, I = 0.30 mol dm-3, LiClO4) showed that these processes involve the slow (t½ = 105 min) partial unravelling of a bdmma ligand from [Ni(bdmma)2]2+, followed by rapid ligand reorganization. The similar rearrangement involving [Ni(bdmma)2]2+ and square-planar [Ni(tfpdma)2]2+ [tfpdma = o -tetrafluorophenylenebis(dimethylarsine)] displays identical kinetic behaviour. In this medium the sequential addition of two pdma ligands to solvated nickel(II) to produce [Ni(pdma)2]2+ has second-order rate constants k1 = 680 and k2 = 210 dm3 mol-1 s-1 respectively at 25.0 °C.

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