15min:

N. R. WALKER, S. L. STEPHENS, V. A. MIKHAILOV AND A. C. LEGON, School of Chemistry, University of Bristol, Bristol, BS8 1TS, U.K..

A Balle-Flygare FT-MW spectrometer coupled to a laser ablation source has been used to measure the pure rotational spectra of H₄C₂ AgCl and H₄C₂ CuCl. Both molecules are generated via laser ablation (532 nm) of a metal rod in the presence of CCl₄, C₂H₄ and argon and are stabilized by supersonic expansion. Rotational constants ( A ₀, B ₀, C ₀) and the centrifugal distortion constant, D _ J , have been measured for six isotopologues of H₄C₂ AgCl and five isotopologues of H₄C₂ CuCl with substitutions at the metal, chlorine and carbon atoms in each case. The spectrum of each molecule is consistent with a C _2v structure in which the metal atom interacts with the -orbital on ethene. The measured rotational constants allow determination of the length of the bond between the metal and chlorine atoms, r _MCl, and the distance between the metal atom and the centre of the ethene double bond, r _MEt. Nuclear quadrupole coupling constants have been determined for the chlorine atom in each molecule and also for copper in H₄C₂ CuCl.