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Heavier Alkyne-Ni0 Complexes, [R2E2·Ni] (E = Sn, Pb), Exhibiting σ-Complex Character
Leopold Junge1, Emeric Schubert1, Israel Fernández2
1Fakultät für Chemie, Technische Universität München, Garching, Germany.
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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, [(CyLE)2·Ni] (5 and 6; CyL = [{Cy2PCH2Si(iPr)2}(Dipp)N]-; Dipp = 2,6-iPr2C6H3). Although these systems cannot be accessed by direct addition of the EI dimers to a Ni0 synthon (i.e. Ni(cod)2; cod = 1,5-cyclooctadiene), we report a novel reductive group elimination pathway, forming the EI dimers from EII synthons in the coordination sphere of Ni, for example, through H2 elimination from SnII hydride compounds. Structural analyses in combination with computational studies indicate that these species are best described as σ-complexes of EI dimers with a transition metal centre, representing a new bonding mode in organometallic coordination chemistry.
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