			15min:

MICROWAVE SPECTRA AND GEOMETRIES OF H₂C₂ cdots

AgCl AND H₂C₂ cdots

CuCl .

N. R. WALKER, S. L. STEPHENS, W. MIZUKAMI, D. P. TEW AND A. C. LEGON, School of Chemistry, University of Bristol, Bristol, BS8 1TS, U.K..

Pure rotational spectra of the vibrational ground states of H₂C₂ cdots AgCl and H₂C₂ cdots CuCl have been measured by chirped-pulse FTMW spectroscopy. Each complex is generated via laser ablation of the metal in the presence of small percentages of CCl₄ and C₂H₂ in argon. The complexes are stabilized and interrogated in the cold environment of a supersonic jet. Rotational constants ( B ₀, C ₀) and the centrifugal distortion constant, Delta _ J , have been measured for six isotopologues of H₂C₂ cdots AgCl and three isotopologues of H₂C₂ cdots CuCl with substitutions at the metal, chlorine and carbon atoms in each case. The spectrum of each complex is consistent with a C _2v structure in which the metal atom is coordinated by the -orbital of ethyne. The measured rotational constants allow determination of the length of the bond between the metal and chlorine atoms, r (M\textemdashCl), and the distance between the metal atom and the centre of the ethyne double bond, r (M\textemdash*). Nuclear quadrupole coupling constants have been measured for the chlorine atom in each complex and also for copper in H₂C₂ cdots CuCl.