THE MICROWAVE-SPECTRUM OF THE ISOTHIAZOLE-ARGON VAN-DER-WAALS COMPLEX

Using molecular beam Fourier transform microwave spectroscopy I:measured and assigned the rotational spectra of the S-32- and (34)-isothiazole-argon complexes. The rotational constants are A' = 3479.53543(15) MHz, B' = 1225.68820(9) MHz, and C' = 1154.69246(11) MHz for S-32-isothiazole-argon and A'= 3428.10063(23) MHz, B' = 1216.56872(19) MHz, and C'= 1140.87783(24) MHz for the S-34-isotopomer. The N-14 quadrupole coupling constants X(aa) = 1.3824(17) MHz, X(bb) = 0.9126(17) MHz, X(cc) = -2.2951(17) MHz, and /x(bc)/ = 2.804(35) MHz could be extracted from the analysis of the spectra. For the S-34-isotopomer I derived x(aa)=1.3907(17)MHz, X(bb)=0.9242(20), X(cc) = -2.3148(20)MHz, and /X(bc)/ = 2.829(55)MHz. The spectroscopic constants were used to propose a structure of the isothiazole-argon van der Waals complex. The argon atom is located 3.55 Angstrom above the ring plane.