Heavier Alkyne‐Ni ⁰ Complexes, [R ₂ E ₂ ·Ni] (E = Sn, Pb), Exhibiting σ‐Complex Character

Abstract

ABSTRACT Despite the ubiquitous nature of alkyne‐transition metal complexes in synthesis and catalysis, analogous examples for the heavier group 14 elements are extremely rare. Here, we describe access to the first such species for Sn and Pb in nickel(0) complexes, [( Cy LE) 2 ·Ni] ( 5 and 6 ; Cy L = [{Cy 2 PCH 2 Si( i Pr) 2 }(Dipp)N] − ; Dipp = 2,6‐ i Pr 2 C 6 H 3 ). Although these systems cannot be accessed by direct addition of the E I dimers to a Ni 0 synthon (i.e. Ni(cod) 2 ; cod = 1,5‐cyclooctadiene), we report a novel reductive group elimination pathway, forming the E I dimers from E II synthons in the coordination sphere of Ni, for example, through H 2 elimination from Sn II hydride compounds. Structural analyses in combination with computational studies indicate that these species are best described as σ‐complexes of E I dimers with a transition metal centre, representing a new bonding mode in organometallic coordination chemistry.