MICROWAVE-SPECTRA AND STRUCTURE OF AN ISOXAZOLE-CO VAN-DER-WAALS COMPLEX

The microwave spectra of an isoxazole-CO complex and four of its isoto pomers have been measured between 7 and 18 GHz with a pulsed nozzle Fo urier transform microwave spectrometer. Rotational constants, centrifu gal distortion constants, and N-14 quadrupole coupling constants have been fitted to the measured transition frequencies of each isotopomer. The permanent electric dipole moment has been determined from Stark e ffect splittings. A unique structure has been found for the complex by taking both the moments of inertia of the isotopomers and the quadrup ole splittings into account. The complex is planar, with CO lying appr oximately radially away from nitrogen in the isoxazole ring. (C) 1998 American Institute of Physics. [S0021-9606(98)00437-1].