MICROWAVE-SPECTRA AND QUADRUPOLE COUPLING MEASUREMENTS FOR METHYL RHENIUM TRIOXIDE

Microwave rotational transitions for J' <-- J = 1 <-- 0 and 2 <-- 1 we re measured in the 6-14 GHz range for methyl rhenium trioxide using a Flygare-Balle type, pulsed-beam spectrometer. The rotational constants for the most abundant isotopomers are B(Re-187) = 3466.964(2) MHz and B(Re-185) = 3467.049(3) MHz. The quadrupole coupling strengths are eQ q(Re-187) = 716.55(2) MHz and eQq(Re-185) = 757.19(3) MHz. Transitions were also observed for C-13 isotopomers and O-18 isotopomers. The val ue for the Re-C bond length obtained from a Kraitchman analysis is R(R e-C) = 2.080 Angstrom. The rhenium quadrupole coupling strengths are a bout 20% smaller than those obtained for HRe(CO)(5).