Reactions of Phenyllithium with the Stannylene Ar*SnPh (Ar* = C<sub>6</sub>H<sub>3</sub>-2,6-Trip<sub>2</sub>; Trip = C<sub>6</sub>H<sub>2</sub>-2,4,6-Pr<sup>i</sup><sub>3</sub>) and the Synthesis of the Distannylstannylene Sn(SnPh<sub>2</sub>Ar*)<sub>2</sub>: Contrasting Behavior in Methyl and Phenyl Derivatives
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The reaction of LiPh with Ar*SnPh (Ar* = C6H3-2,6-Trip2; Trip = C6H2-2,4,6-Pri3) afforded either the monomeric etherate (Et2O)LiSnPh2Ar* (1) or the dimer (LiSnPh2Ar*)2 (2). The reaction of 2 with SnCl2 in a 1:1 ratio in Et2O yielded the monomeric distannylstannylene Sn(SnPh2Ar*)2 (3). The compounds 1−3 were characterized by 1H, 7Li, 13C, and 119Sn NMR and UV−vis spectroscopy. Complete single-crystal X-ray crystal structures of 2 and 3 were determined as well as a partial structure for 1. The structure of 1 showed that the tin was pyramidally coordinated by the three organic groups as well as by lithium. The lithium was found to be ligated by ether and η6-coordinated by one of the phenyl rings. The structure of 2 showed that it was dimerized through η6-interactions of a tin-coordinated lithium with a phenyl group of a partner monomer rather than through tin−tin bonding. The structure of 3 featured a central, two-coordinate tin(II) bound to two SnPh2Ar* groups with long Sn−Sn distances near 2.96 Å and a very wide Sn−Sn−Sn angle of 115.19(2)°. The 119Sn NMR chemical shift of the central tin is 3752 ppm, which is the furthest downfield 119Sn NMR chemical shift recorded for a stannylene.
