Homo- and Heteroleptic Silylstannylenes: Synthesis, Structure and Use as Precursors to Bimetallic Compounds

Two novel silyl-substituted
stannylenes are reported: ArMesSn{Si(SiMe3)2(SitBuPh2)} (ArMes = 2,6-Mes2C6H3, Mes = 2,4,6-Me3C6H2) and Sn{Si(SiMe3)2(SitBuPh2)}2, the latter representing a
very rare example of a homoleptic disilyl
stannylene Together with the known stannylene ArMesSn{Si(SiMe3)3}, these systems are each shown to insert into
the Au–Cl bond of (Ph3P)AuCl to form complexes of
the type (Ph3P)Au(SnR2Cl) containing four coordinate
stannyl ligands (where R = aryl or silyl group). Similar behavior
is shown toward (Cy3P)AuI, yielding crystalline (Cy3P)Au{SnI(ArMes)(Si(SiMe3)3)} in the case of ArMesSn{Si(SiMe3)3}. Subsequent iodide abstraction to yield [(Cy3P)Au{Sn(ArMes)(Si(SiMe3)3)}]+ can be
achieved using Li[Al(ORf)4]
(Rf = −C(CF3)3), facilitated by the long tin–halide bond and strongly electron-donating
tertiary phosphine ligand. This cationic complex represents the first
structurally characterized example of a simple (two-coordinate) stannylene
ligand bound to a gold center in a manner analogous to classical Au(I)
carbene complexes.