MOLECULAR-STRUCTURE OF TIN(II) ACETATE AS DETERMINED IN THE GAS-PHASEBY ELECTRON-DIFFRACTION AND AB-INITIO CALCULATIONS

The gas-phase structure of tin(II) acetate, Sn(O2CCH3)(2), has been de termined by electron diffraction augmented by flexible restraints deri ved from ab initio molecular orbital calculations at the DZ(P)/MP2 lev el. The structure, with C-2 symmetry can be regarded as a highly disto rted trigonal bipyramid, with the lone pair of electrons on tin occupy ing one of the equatorial sites. The four-membered rings and the aceta te groups were both found to adopt near-planar arrangements. The two e quivalent acetate groups are asymmetrically bonded to tin, with Sn-O(4 ) 233.7(12) and Sn-O(5) 219.2(8) pm, and form a narrow bite angle at t in, with O(4)-Sn-O(5) 58.1(2)degrees; other important experimental str uctural parameters (r(a)) are C(2)-O(4) 124.5(5), C(2)-O(5) 127.5(5) a nd C(2)-C(8) 151.0(5) pm, C(2)-Sn-C(3) 95.1(12), O(4)-C(2)-O(5) 122.0( 4) and O(4)-Sn-C(2)-O(5) 176.3(16)degrees and the acetate groups are t wisted about the Sn ... C axis by 16.8(11)degrees away from a rhomboid al-based pyramid.