Anomeric and mesomeric effects in methoxycarbonylsulfenyl chloride, CH(3)OC(O)SCl: an experimental and theoretical study.
The molecular structure and conformational properties of methoxycarbonylsulfenyl chloride, CH(3)OC(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-CH(3) 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 DeltaG between the syn and anti conformers. The results are discussed in terms of anomeric effects and a natural bond orbital (NBO) calculation. Photolysis of matrix-isolated CH(3)OC(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.
Erben
Mauricio F
MF
CEQUINOR (UNLP, CONICET), Departamento de Quimica, Facultad de Ciencias Exactas, y Laboratorio de Servicios a la Industria y al Sistema Científico, Universidad Nacional de La Plata, 47 esquina 115 (1900) La Plata, República Argentina.
Della Védova
Carlos O
CO
Romano
Rosana M
RM
Boese
Roland
R
Oberhammer
Heinz
H
Willner
Helge
H
Sala
Oswaldo
O