MICROWAVE-SPECTRUM AND MOLECULAR-STRUCTURE OF THE H2NS RADICAL

The rotational spectral lines of the H2NS and D2NS radicals in the (X) over tilde(2)B(1) electronic ground state are observed with a source- modulation microwave spectrometer and a Fourier-transform microwave sp ectrometer. Molecular constants including hyperfine interaction consta nts are determined for H2NS and D2NS by a least-squares method. By usi ng the obtained centrifugal distortion constants and inertial defects, the harmonic force field is evaluated, and the frequency of the yq vi brational mode (out of plane) is calculated to be 325 cm(-1). This val ue is much smaller than that of the related molecule H2CS, indicating a floppy motion along the out-of-plane mode. The zero-point vibrationa l average structure was determined as follows; r(z)(N-H)=1.000(5) Angs trom, r(z)(N-S)=1.6398(13) Angstrom, and angle(z)(HNH)=118.9(7)degrees , where the numbers in parentheses represent three times the standard deviation. (C) 1998 American Institute of Physics.