Abstract
The reaction of phosphine-appended (amido)(aryl)stannylenes (1) with Ni(0) synthons leads to the facile formation of chelating-stannylene Ni(0) complexes (2-4). Utilising the carbene-stabilised synthon IPr·Ni·(η (6)-toluene) (IPr = [(H)CN(Dipp)](2)C:; Dipp = 2,6-(i)Pr(2)C(6)H(3)) leads to the high-yielding formation of targeted 16-electron Ni(0) complexes. These systems activate H(2) under non-forcing conditions (1 bar, RT), all forming the same single product, 5, which is found to be a mono-hydrido stannylene complex. Alternative synthetic routes in combination with computational calculations demonstrate that this species features a bridging (i.e. [Sn-(µ-H)-Ni]) hydride ligand, and may be described either as an agostic [Sn-H-Ni] bonded hydrido-stannylene complex, or a formal nickelo-stannylene. The formation of compound 5 arises from the metathesis of the Sn-C(Ar) bonds with H(2), leading to the elimination of Ar-H, which is detected by NMR and mass spectroscopic methods. The mechanism for this process, explored using DFT methods, proceeds through Ni-centre H(2) binding, Sn-Ni cooperative hydrogen activation, and subsequent Ar-H elimination via a cooperative C-H bond formation at the Ni and Sn centres. Finally, complex 5 is shown to undergo further Ph-H elimination of a single aryl group of the chelating phosphine arm with the bridging hydride ligand, forming a unique nickelo-stannylene complex 7, which features two formally Sn(0) metallostannylene centres binding Ni(II).