Spontaneous Si–C bond cleavage in (TriphosSi)-nickel complexes

Abstract

Herein, we report on the versatile reactions of CH₃C(CH₂PPh₂)₃ as well as CH₃Si(CH₂PPh₂)₃ derived Ni-complexes. While Ni[CH₃C(CH₂PPh₂)₃] complexes reveal high stability, the Ni[CH₃Si(CH₂PPh₂)₃] analogs show rapid decomposition at room temperature and afford the unprecedented pseudo-tetrahedral phosphino methanide complex 5. We provide a detailed electronic structure of 5 from X-ray absorption and emission spectroscopy data analysis in combination with DFT calculations, as well as from comparison with structurally related complexes. A mechanistic study for the formation of complex 5 by reaction with BF₄⁻ is presented, based on a comparison of experimental data with quantum chemical calculations. We also show a simple route towards isolable Ni(I)-complexes on the gram scale.