10min:

JESSICA SCHLIER, STEWART E. NOVICK AND W. C. PRINGLE, Department of Chemistry, Wesleyan University, Middletown, CT 06459; D. MCCAMANT, Department of Chemistry, University of California , Berkeley, CA 94720.

The Fourier Transform Pulsed Jet Microwave spectra of the argon-thietane (C₄H₆S) van der Waals complex has been assigned for four isotopomers including ³²S and ³⁴S and each of the ¹³C ³²S isotopomers. We previously reported analysis of the parent spectrum. The argon freezes out the ring inversion and converts the inversion dipole moment to a permanent moment. Using the isotopomers yields the unambiguous position of the argon that could not be determined from the parent complex alone. The argon is 3.780 Å~above the plane containing the C-S-C bond and is 0.576 Å~across the ring from the plane perpendicular to this angle containing the bisector of C-S-C angle. The CH₂ across the ring from the sulfur is below the C-S-C plane. This latter position could only be determined using isotopomers. Large amplitude cross ring argon motion causes the two carbons bonded to the sulfur to be equivalent.