The structure of ( iBu 3Sn) 2CO 3 and (Me 3Sn) 2CO 3 in solution and in the solid state studied by 13C/ 119 Sn NMR spectros

Abstract

The structures of two bis(triorganotin) carbonates (R 3Sn) 2CO 3, with R  Me ( 1a) or iBu ( 1b), have been determined by low temperature single crystal X-ray diffraction studies. The crystal structure of 1a (previously determined at room temperature) has been redetermined at 200 K, at which the structure of 1b has also been determined. Both compounds have similar polymeric structures; trigonal-planar R 3Sn moieties are axially bridged by bidentate R 3Sn-O-CO 2 units to trigonal-pyramidal R 3Sn moieties in such a way that helices parallel to the crystallographic c-axes are formed. There are differences in the number of the structural units (R 3Sn tpy(R 3Sn tpl)CO 3 needed for a complete screw thread, namely, two for 1a and four for 1b. 13C and 119Sn high resolution solid-state NMR spectroscopy are consistent with the structural findings but also the existence of dynamic processes (on the NMR time scale) for solid 1a at room temperature. Structural differences between the solid state and solution can be rationalised by comparison of solid and solution state NMR spectroscopy.