Synthesis and Characterization of a Linear, Two-Coordinate Pt(II) Ketimide Complex.

Herein we report the synthesis and characterization of a linear, two-coordinate Pt(II) ketimide complex, Pt(N═CtBu2)2 (1), formed via the reaction of PtCl2(1,5-COD) with 2 equiv of Li(N═CtBu2). Also generated in the reaction is the bimetallic complex [(tBu2C═N)Pt(μ-N,C-N═C(tBu)C(Me)2CH2)Pt(N═CtBu2)] (2). Both complexes 1 and 2 have been characterized by NMR spectroscopy and X-ray crystallography. Notably, complex 1 exhibits short Pt-N distances (av. Pt-N = 1.817 Å) and an unusually deshielded 195Pt chemical shift (δPt = -629 ppm) with a large 1J(195Pt,14N) coupling constant (537 Hz). These data, in combination with a detailed density functional theory electronic structure analysis, reveal the presence of highly covalent Pt═N multiple bonds formed by a combination of σ-donation, π-donation, and π-backdonation.