Reactions of Phenyllithium with the Stannylene Ar*SnPh (Ar* = C6H3-2,6-Trip2; Trip = C6H2-2,4,6-Pri3) and the Synthesis of the Distannylstannylene Sn(SnPh2Ar*)2: Contrasting Behavior in Methyl and Phenyl Derivatives

Abstract

The reaction of LiPh with Ar*SnPh (Ar* = C 6 H 3 -2,6-Trip 2 ; Trip = C 6 H 2 -2,4,6-Pr i 3) afforded either the monomeric etherate (Et 2 O)LiSnPh 2 Ar* (1) or the dimer (LiSnPh 2 Ar*) 2 (2). The reaction of 2 with SnCl 2 in a 1:1ratio in Et 2 O yielded the monomeric distannylstannylene Sn(SnPh 2 Ar*) 2 (3). The compounds 1-3 were characterized by 1 H, 7 Li, 1 3 C, and 1 1 9 Sn 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 η 6 -coordinated by one of the phenyl rings. The structure of 2 showed that it was dimerized through η 6 -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 SnPh 2 Ar* groups with long Sn-Sn distances near 2.96 A and a very wide Sn-Sn-Sn angle of 115.19(2)°. The 1 1 9 Sn NMR chemical shift of the central tin is 3752 ppm, which is the furthest downfield 1 1 9 Sn NMR chemical shift recorded for a stannylene.