SULFUR COMPOUNDS .178. GAS-PHASE STRUCTURE AND VIBRATIONAL-SPECTRA OFDIMETHOXYDISULFANE, (CH3O)(2)S-2

The gas-phase structure of dimethoxydisulfane (CH3O)(2)S-2 was determi ned by electron diffraction. The molecule is chainlike and of symmetry C-1. Selected experimental geometrical parameters are d(SS) 196.0(3) pm, d(SO) 165.3(3) pm, d(CO) 143.2(3) pm, alpha(OSS) 108.2(3)degrees, alpha(COS) 114.5(4)degrees, tau(SS) 91(4)degrees, tau(SO) +/- 7(3)degr ees. Abinitio MO calculations at the HF/6-311G* level resulted in thr ee conformational isomers originating from rotation about the two SO b ond axes. The most stable conformer among these is in keeping with the gasphase structure. The two other rotamers are both of symmetry C-2. Infrared and Raman spectra of gaseous, liquid, and crystalline dimetho xydisulfane and its fully deuterated derivative were recorded. The 30 fundamental modes were assigned using the vibrational wavenumbers calc ulated for the three rotamers by the ab-initio MO method.