SPECTRA AND STRUCTURE OF ORGANOPHOSPHORUS COMPOUNDS .54. MICROWAVE-SPECTRUM, AB-INITIO CALCULATIONS AND STRUCTURE OF METHYLPHOSPHONOTHIOIC DIFLUORIDE

The microwave spectrum of CH3P(S-34)F-2 has been measured in the regio n 28.0 to 36.0 GHz and the rotational constants determined: A = 4366.0 , B = 2522.8 and C = 2428.6 MHz. By utilizing six rotational constants , three of which were previously determined for CH3P(S-32)F-2, structu ral parameters have been obtained for methylphosphonothioic difluoride . These structural parameters are significantly different from those w hich were previously proposed. A comparison is given between the micro wave-determined structural parameters and those obtained from ab initi o calculations with the RHF/6-31G basis set for molecules of the type (CH3)(n)P(S)F-3-n where n = 0, 1, 2 and 3.