Structural systematics of the triorganotin carboxylates: The crystal and molecular structures of polymeric Me3Sn(O2CCH3−x Cl x ); x = 0 – 3

Abstract

Abstract The crystal and molecular structures of four Me3Sn(O2CCH3−x Cl x ), x = 0 – 3, compounds have been determined at 200 K. The colorless crystals of [Me3Sn(O2CCH3)] are orthorhombic, space group Pnma with unit cell dimensions a = 10.569(4) Å, b = 7.876(9) Å, c = 9.719(9) Å, V = 809(1) Å3, Z = 4 and D x = 1.829 Mg m−3. The colorless crystals of [Me3Sn · (O2CCH2Cl)] are monoclinic, space group P21/c with unit cell dimensions a = 12.564(6) Å, b = 10.093(5) Å, c = 14.44(1) Å, β = 98.62(5)°, V = 1810(1) Å3, Z = 8 and D x = 1.888 Mg m−3. Crystals of colourless [Me3Sn · (O2CCHCl2)] are monoclinic, space group P21/n with unit cell dimensions a = 10.013(5) Å, b = 16.60(1) Å, c = 12.467(6) Å, β = 103.71(4)°, V = 2012(1) Å3, Z = 8 and D x = 1.925 Mg m−3. The colorless crystals of [Me3Sn(O2CCl3)] are monoclinic, space group P21/n with unit cell dimensions a = 9.124(4) Å, b = 9.941(6) Å, c = 12.119(5) Å, β = 102.22(4)°, V = 1074.3(8) Å3, Z = 4 and D x = 2.016 Mg m−3. The structures were solved by direct methods and each refined by a full-matrix least-squares procedure to final R = 0.034 using 876 reflections for [Me3Sn(O2CCH3)]; to R = 0.041 using 2556 reflections for [Me3Sn(O2CCH2Cl)]; to R = 0.045 using 3301 reflections for [Me3Sn(O2CCHCl2)]; and to final R = 0.038 reflections for [Me3Sn(O2CCl3)]. Each of the four structures adopts a similar polymeric motif owing to the presence of bidentate bridging carboxylate ligands. This arrangement leads to the presence of trans-R3SnO2 tin atom geometries. There is no apparent correlation between the pKa values of the carboxylate ligands and the derived interatomic parameters, suggesting that crystal packing effects may exert an influence on these parameters. The solution structures of these compounds are shown by spectroscopy (infrared, 1H NMR) to be monomeric with tetrahedral tin atom geometries.