A fluxional binuclear nickel(I) complex and evidence for reversible A-frame formation

The synthesis, structure, and fluxionality of the unusual dinickel(I) complex [Ni 2 Cl 2 (μ-CO)(μ-dppm) 2 ] (1a), dppm=Ph 2 PCH 2 PPh 2 are described. Complex 1a is formed by reaction of nickel(0) with nickel(II), in particular by reaction of [Ni 2 (CO) 2 (μ-CO)(μ-dppm) 2 ] with [NiCl 2 (dppm) 2 ] or of [Ni(CO) 2 (dppm-P) 2 ] with NiCl 2 .6H 2 O