Fourier transform microwave spectroscopy of HSiBr: exploring the Si-Br bond through quadrupole hyperfine coupling.
The 1(01)-0(00) (9-10 GHz) and 2(02)-1(01) (18-19 GHz) rotational transitions of HSi 79Br and HSi 81Br have been measured in a pulsed discharge jet expansion to an experimental uncertainty of approximately 1 kHz using Fourier transform microwave spectroscopy. The data have yielded an effective rotational constant, the centrifugal distortion constant Dj, the bromine nuclear quadrupole coupling constants, and the bromine nuclear spin-molecular rotation interaction parameter for both isotopomers. The derived parameters have been compared to their values calculated ab initio, and the nuclear quadrupole coupling tensor has been used to investigate the Si-Br bond, giving a sigma bond ionic character of 0.60, a pi bond character of 0.22, and a total Si-Br ionic character of 0.38. These bond characteristics have been compared to trends in other halosilylenes, silanes, and the analogous carbenes.
Department of Chemistry, University of Kentucky, Lexington, Kentucky 40506-0055, USA.
Brandon S
BS
Tackett
Dennis J
DJ
Clouthier
Jennifer N
JN
Landry
Wolfgang
W
Jäger