THE MICROWAVE-SPECTRA OF ISOTOPIC THIOPHOSPHORYL CHLORIDES IN THE GROUND AND V(6)=1 VIBRATIONAL-STATES

The pure rotational spectra of five isotopic species of thiophosphoryl chloride, SPCl3, have been examined in detail in the frequency range 26-110 GHz. This study has shown that the frequencies previously repor ted for the rotational transitions of three symmetric-top species of S PCl3 in the ground state are, in fact, due to molecules in the vibrati onally excited state nu(6) = 1. In this work we have measured for the first time rotational transitions for the (SPCl3)-S-32-Cl-35, (SPCl3)- S-34-Cl-35, and (SPCl3)-S-32-Cl-37 symmetric-top species in their grou nd vibrational states. In order to determine an accurate molecular geo metry, the spectra of the asymmetric-top species (SPCl2Cl)-S-32-Cl-35- Cl-37 and (SPClCl2)-S-32-Cl-35-Cl-37 were also recorded. The data obta ined have been analyzed to yield values for rotational constants and q uartic centrifugal distortion constants. Our results have been used, t ogether with literature vibrational data, to refine an accurate harmon ic force field for SPCl3. We have also evaluated effective, substituti on, average, and approximate equilibrium values for internuclear param eters. The ground state average structural parameters of SPCl3 are r(z )(PS) = 1.8835(7) Angstrom, r(z)(PCl) = 2.0093(3) Angstrom, and angle( SPCl) = 116.35(2)degrees. (C) 1996 Academic Press, Inc.