THE MICROWAVE-SPECTRUM AND MN-H BOND-LENGTH FOR HMN(CO)5

The microwave rotational spectrum for the symmetric top, manganese pentacarbonylhydride, was measured in the 5-11 GHz range using a pulsed-beam, Fourier transform microwave spectrometer. For HMn(CO)5 we obtained A = B = 907.9841 (2) MHz and eqQ(Mn) = -44.22(2) MHz. For DMn(CO)5, A = B = 902.7682(3) MHz and eqQ(Mn) = -45.24(4) MHz. Only K = 0 and K = 4 transitions were observed, confirming the expected C4v symmetry. With other structural parameters constrained to previously reported values, r0(Mn-H) = 1.64(4) angstrom. The C(ax)-Mn-C(eq) angle derived from the data is approximately 97-degrees, if Mn-C-O angles are constrained to 180-degrees.