The rotational spectrum of the benzonitrile‐argon van der Waals complex

Abstract

AbstractThe microwave spectra of 14N‐ and 15N‐benzonitrile‐argon have been recorded using a pulsed molecular beam Fourier transform microwave spectrometer. In the case of 14N‐benzonitrile‐argon, the rotational constants were determined to be A = 1347.7899(12) MHz, B = 1006.02030(94) MHz, C = 719.81749(24) MHz. The quartic centrifugal distortion constants (van Eijck) are D'J = 3.9982(14) kHz, D'JK = −15.3062(79) kHz, D'K = 21.8510(92) kHz, d'J = 1.65065(83) kHz, R'6 = 0.03043(38) kHz, and the 14N‐nuclear quadrupole coupling constants are χaa = −0.4479(17) MHz, χbb‐χcc = −4.1255(17) MHz. For 15N‐benzonitrile‐argon the rotational constants were found to be A = 1335.09150(30) MHz, B = 989.86421(15) MHz, and C = 707.91548(07) MHz. The centrifugal distortion constants are of the same magnitude as for the 14N‐isotopomer. The argon atom is placed 3.545 Å above the center of the ring plane. In addition, the spectra of benzonitrile and six isotopic species have been reinvestigated; the derived constants and the resulting structure are of higher accuracy than in earlier work.