MICROWAVE SPECTRA AND STRUCTURES OF H$_{4}$C$_{2}$$\cdots$AgCl AND H$_{4}$C$_{2}$$\cdots$CuCl

Abstract

A Balle-Flygare FT-MW spectrometer coupled to a laser ablation source has been used to measure the pure rotational spectra of H$_{4}$C$_{2}$$\cdots$AgCl and H$_{4}$C$_{2}$$\cdots$CuCl. Both molecules are generated via laser ablation (532 nm) of a metal rod in the presence of CCl$_{4}$, C$_{2}$H$_{4}$ and argon and are stabilized by supersonic expansion. Rotational constants ({\it{A}}$_{0}$, {\it{B}}$_{0}$, {\it{C}}$_{0}$) and the centrifugal distortion constant, {\it{D}}$_{\it{J}}$, have been measured for six isotopologues of H$_{4}$C$_{2}$$\cdots$AgCl and five isotopologues of H$_{4}$C$_{2}$$\cdots$CuCl with substitutions at the metal, chlorine and carbon atoms in each case. The spectrum of each molecule is consistent with a {\it{C}}$_{2v}$ structure in which the metal atom interacts with the ${\pi}$-orbital on ethene. The measured rotational constants allow determination of the length of the bond between the metal and chlorine atoms, {\it{r}$_{\rm{MCl}}$}, and the distance between the metal atom and the centre of the ethene double bond, {\it{r}$_{\rm{MEt}}$}. Nuclear quadrupole coupling constants have been determined for the chlorine atom in each molecule and also for copper in H$_{4}$C$_{2}$$\cdots$CuCl.