Tetra- and Triarylantimony Fluorobenzoates: Synthesis and Structures

The reactions of pentaarylantimony (Ar₅Sb, where Ar = Ph or p-Tol) with triarylantimony bis(pentafluorobenzoate) and triarylantimony bis(3,4,5-trifluorobenzoate) in toluene afforded tetraarylantimony pentafluoro- and 3,4,5-trifluorobenzoates in up to 90% yields. The starting triarylantimony bis(pentafluorobenzoates) and bis(3,4,5-trifluorobenzoates) were prepared in ether by oxidative addition involving triarylstibine, hydrogen peroxide, and pentafluorobenzoic or 3,4,5-trifluorobenzoic acid, respectively, in up to 98% yields. Tetra-p-tolylantimony pentafluorobenzoate and triphenylantimony bis(pentafluorobenzoate) were structurally characterized by X-ray diffraction analysis. The coordination polyhedron of the Sb atoms is a distorted trigonal bipyramid with axial carboxy groups. In these compounds, the Sb atoms and carbonyl O atoms are linked by intramolecular contacts, which are especially pronounced in the latter complex (the Sb···O(=C) distances are 3.377(3) and 2.943(2), 3.167(2) Å, respectively).