Anomeric and Mesomeric Effects in Methoxycarbonylsulfenyl Chloride, CH3OC(O)SCl: An Experimental and Theoretical Study

ERBEN, M.F.; DELLA VÉDOVA, C.O.; ROMANO, R.M.; BOESE, R.; OBERHAMMER, H.; WILLNER, H.; SALA, O.

INORGANIC CHEMISTRY

American Chemical Society

Año: 2002 vol. 41 p. 1064 - 1071

0020-1669

The molecular structure and conformational properties of methoxycarbonylsulfenyl chloride, CH3OC(O)SCl, were determinated in the gas and solid phases by gas electron diffraction, low-temperature X-ray diffraction, and vibrational spectroscopy. Furthermore, quantum chemical calculations were performed. Experimental and theoretical methods result in structures with a planar C-O-C(O)-S-Cl skeleton. The electron diffraction intensities are reproduced best with a mixture of 72(8)% syn and 28(8)% anti conformers (S-Cl bond synperiplanar/antiperiplanar with respect to C=O bond) and the O-CH3 bond synperiplanar with respect to the C-O bond. The syn form is the preferred form and becomes the exclusive form in the crystalline solid at low temperature. This experimental result is  reproduced very well by Hartree-Fock approximation and by density functional theory at different levels of theory but not by the MP2/6-311G* method, which overestimates the value of DG° between the syn and anti conformers. The results are discussed in terms of anomeric effects and a natural bond orbital (NBO) calculation. Photolysis of matrixisolated CH3OC(O)SCl with broad-band UV-visible irradiation produces an interconversion of the conformers, and the concomitant decomposition leads to formation of OCS and CO molecules.