Microwave spectrum and molecular conformation of (E)-benzaldehyde oxime

The microwave spectrum of (E)-benzaldehyde oxime, C6H5-CH=NOH and C6H5-CH=N OD, has been observed in the frequency range from 26.5 to 40.0 GHz. The spe ctrum of the ground vibrational state was assigned and fitted to the Watson 's A-reduced Hamiltonian to obtain these rotational and centrifugal distort ion constants: A = 5183.13(29) MHz, B = 895.367(3) MHz, C = 763.819(3) MHz, Delta(J) = 0.019(3) kHz, and Delta(JK) = 0.204(7) kHz for the normal speci es, and A = 5158.4(23) MHz, B = 869.44(2) MHz, C = 744.34(2) MHz, Delta(J) = 0.023(2) kHz, and Delta(JK) = 0.193(7) kHz for the deuterated species. Th e values of the Delta I (=I-c - I-a - I-b) obtained for the normal and deut erated species were -0.295(6) and -0.28(5) a.m.u. Angstrom(2), respectively . The molecular conformation of this molecule was a planar one in which the values of the dihedral angles, CCNO and CNOH, were almost 180 degrees and 180 degrees, respectively. (C) 1999 Academic Press.