Solution- and solid-state coordination behaviour of omega-trichlorostannyl alcohols, HO(CH(2))nSnCl(3)(n=3-5): X-ray diffraction, multinuclear NMR, and AM1 quantum chemical studies

Abstract

The coordination behavior of ω-trichlorostannyl alcohols of the type HO(CH2)nSnCl3 (n = 3−5) has been investigated by solid-state 13C and 117Sn NMR, by 1H, 13C, 119Sn, and 17O as well as gradient-assisted 2D 1H−119Sn HMQC and 119Sn EXSY NMR spectroscopy in CD2Cl2 and acetone-d6 solutions, by X-ray diffraction for the C5 (n = 5) alcohol, and AM1 quantum mechanical calculations. The crystal structure of the C5 alcohol reveals a polymeric structure that arises from significant intermolecular HO → Sn interactions of 2.356(6) Å. The tin atom is thus five-coordinate and exists in a distorted trigonal bipyramidal geometry with the oxygen and one of the chloride atoms defining the axial positions. The polymeric nature of the C5 alcohol explains its insolubility, unlike the C3 and C4 alcohols, in CD2Cl2 solution. In this solvent, the C3 and C4 alcohols display almost exclusively intramolecular HO → Sn coordination, resulting in five- and six-membered ring structures, respectively. In the C5 alcohol, the solid-state intermolecular HO → Sn interaction is too strong for CD2Cl2 to break up the polymer. The acetone-d6 NMR data reveal a complex coordination behavior combining five- and six-coordinated species in fast equilibrium in which HO → Sn and (CD3)2CO → Sn interactions are evidenced. This behavior is accompanied by very slow hydrolysis, observed in acetone but not in dichloromethane, ascribed to limited slow acetone autocondensation.