The Rotational Spectrum of Monothioformic Acid. II. cis-and trans-HC(:O)SD, DC(:O)SH, HC(:O)34 SH1,2

Abstract

Abstract The rotational spectra of three isotopically substituted species of monothioformic acid, DCOSH, HCOSD, HCO34SH, have been investigated. Transitions arising from two different isomeric forms have been observed in each instance. Rotational constants and quartic centrifugal distortion constants have been determined for all species using Watson’s reduced Hamiltonian. It has been established that the two abundant isomers of monothioformic acid are the planar cis and trans thiol rotamers. The structure of cis-HC ( :O ) SH is found to be: r ( C - H ) =1.100 Å, r ( S - H ) =1.336 Å, r ( C - S ) =1.771 Å, r(C=0) =1.210 Å, ∢(OCS) =122.4°, ∢(HSC) =94.7° and ∢(HCS) = 114.6°; whereas for trans-HC ( :O ) SH: r(C - H ) =1.100 Å, r (S - H) =1.351 Å, r (C - S) = 1.763 Å, r(C=O) = 1.218 Å, ∢(OCS) =126.0°, ∢(HSC) = 92.7 ° and ∢(HCS) =111.8°.