THE STRUCTURE OF ((ISO-BU)3N)2CO3 AND (ME3SN)2CO3 IN SOLUTION AND IN THE SOLID-STATE STUDIED BY C-13/SN-119 NMR-SPECTROSCOPY AND X-RAY-DIFFRACTION

The structures of two bis(triorganotin) carbonates (R3Sn)2CO3, with R = Me (1a) or (i)Bu (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 R3Sn moieties are axially bridged by bidentate R3Sn-O-CO2 units to trigonal-pyramidal R3Sn 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 (R3Sntpy)(R3Sntpl)CO3 needed for a complete screw thread, namely, two for 1a and four for 1b. C-13 and Sn-119 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 la at room temperature. Structural differences between the solid state and solution can be rationalised by comparison of solid and solution state NMR spectroscopy.