Crystal and molecular structures of 1,2;3,4-di-mu-o-methyl/o-chlorobenzoato-OO'-1,3 bis(o-methyl/o-chlorobenzoato-O)-1,2,4;2,3,4-di-mu(3)-oxo tetrakis[di-n-butyltin(IV)] and molecular structure of 1,2;3,4-di-mu-o-hydroxybenzoato-OO'-1,3 bis(o-hydroxybenzoato-O)-1,2,4;2,3,4-di-mu(3)-oxo tetrakis[di-n-butyltin(IV)] compounds

The title distannoxanes [(n-Bu(2)SnO(2)CC(6)H(4)-o-CH3)(2)O](2)(1), [(n-Bu(2)SnO(2)CC(6)H(4)-o-Cl)(2)O](2) (2) and [(n-Bu(2)SnO(2)CC(6)H(4)-o-OH)(2)O](2) (3) were obtained by azeotropic dehydration from a mixture of n-Bu(2)SnO and the appropriate substituted benzoic acids. Single-crystal X-ray diffraction studies revealed that both 1 and 2 have tetranuclear centrosymmetric dimeric structures. The structurally significant bond lengths and bond angles (for 1: Sn(1)-O(3), 2.992 Angstrom; Sn(2)-O(2), 2.929 Angstrom; C(1)-Sn(1)-C(5), 134.8(4)degrees, C(9)-Sn(2)-C(13), 137.7(5)degrees) (for 2: Sn(1)-O(3), 3.012 Angstrom, Sn(2)-O(2), 2.975 Angstrom; C(1)-Sn(1)-C(5), 135.4(5)degrees; and C(9)-Sn(2)-C(13), 136.3(7)degrees) reveal the least distorted trigonal bipyramidal structures at exocyclic and endocyclic tin atoms observed to date. Multinuclei (H-1, C-13 and Sn-119) NMR, Mossbauer and IR spectra are in agreement with the X-ray data. Compound 3 is extremely insoluble in organic solvents. Its IR spectra reveal extensive hydrogen bonding, the extent of which is reduced at higher temperatures (30-60 degrees C). Its Sn-119 NMR spectra in solution at these temperatures show signals usually assigned to five- and six-coordinate organotin species; such species probably arise by breakdown of the structure of 3 found in the solid state. A comparison with the structures of known ortho-substituted distannoxane is presented.