A Ni(0) Methyl Complex Based on a Bimetallic Ni–Ga Framework

Abstract

The Ni(0) methyl complex MeNiGaL was prepared and characterized by XRD, ¹H NMR, ¹³C NMR, ³¹P NMR, ESI-MS, and UV–vis. The compound can be prepared from the 16-valence electron complex NiGaL by addition of MeLi, yielding the corresponding lithium salt. NiGaL is a close derivative of a complex that has been previously reported by Lu et al. The title compound represents a rare example of a Ni(0) alkyl complex. The complex is based on a bimetallic, tripodal framework featuring a Ni–Ga bond. The methyl complex, isolated as its Li(THF)₄ salt, shows no interaction between the lithium cation and the methyl anion in the solid state. UV–vis titration experiments indicate reversible dissociation of MeLi in solution. Attempts to prepare the corresponding neopentyl or CH₂EMe₃ complexes (E = N, P), as possible intermediates or analogues thereof in the nickel catalyzed cyclopropanation of unactivated alkenes with NMe₄OTf/BuLi, were unsuccessful.