Dicoordinate Copper(I) Silanechalcogenolates

The copper silanechalcogenolates tBu3PCuESiPh3 (1, E = O; 2,
E = S; 3, E = Se) were prepared from the reaction of [tBu3PCu(CH3CN)3]BF4 with [Ph3SiELi(THF)2]2 in acetonitrile. The compounds
were obtained as colorless, crystalline, but thermally labile solids.
X-ray crystallography shows that complexes 1−3 are monomeric
in the solid state with no Cu···Cu interactions. The Cu atoms have
either a linear or a near-linear coordination geometry in all three
complexes. Interestingly, the O atom in complex 1 is also linear,
which is in contrast to the highly bent S (2) and Se analogues (3).
Density functional theory calculations suggest that both the linear
geometry of 1 and an associated extremely short Cu−O distance
[1.769(4) Å] are not the result of π delocalization but are the result
of a fine balance of electrostatic interaction and Pauli repulsion.