The synthesis and structure of a dianionic species with a bond between pentacoordinated tin atoms: bonding properties of the tin–tin bond

Abstract

The first dianionic compound bearing a bond between two pentacoordinated tin atoms, a distannate, was synthesized in a stable form by using two sets of an electron-withdrawing C,O-bidentate ligand on each tin atom. The structure of the distannate was determined by NMR spectroscopy and X-ray crystallographic analysis. The Sn–Sn bond of the distannate was shown to be a single bond featuring high s-character. The ¹J(Sn–Sn) coupling constant was larger than that of Sn(sp³)–Sn(sp³) bonds found in most hexaorganodistannanes. This bond feature was also supported by computational studies. The Sn–Sn bond was cleaved by treatment with hydrochloric acid, which shows a different reactivity to the homonuclear bonds of pentacoordinated disilicates and digermanates.