C 2H 2Ag-Cl was formed from ethyne and AgCl in the gas phase and its rotational spectrum observed by both the chirped-pulse and Fabry-Perot cavity versions of Fourier-transform microwave spectroscopy. Reaction of laser-ablated silver metal with CCl 4 gave AgCl which then reacted with ethyne to give the complex. Ground-state rotational spectra of the six isotopologues 12C 2H 2 107Ag 35Cl, 12C 2H 2 109Ag 35Cl, 12C 2H 2 107Ag 37Cl, 12C 2H 2 109Ag 37Cl, 13C 2H 2 107Ag 35Cl, and 13C 2H 2 109Ag 35Cl were analysed to yield rotational constants A 0, B 0, and C 0, centrifugal distortion constants Δ J, Δ JK, and δ J, and Cl nuclear quadrupole coupling constants χ aa(Cl) and χ bb(Cl) -χ cc(Cl). A less complete analysis was possible for 12C 2D 2 107Ag 35Cl and 12C 2D 2 109Ag 35Cl. Observed principal moments of inertia were interpreted in terms of a planar, T-shaped geometry of C 2v symmetry in which the AgCl molecule lies along a C 2 axis of ethyne and the Ag atom forms a bond to the midpoint () of the ethyne π bond. r 0 and rm(1) geometries and an almost complete r s-geometry were established. The ethyne molecule distorts on complex formation by lengthening of the CC bond and movement of the two H atoms away from the CC internuclear line and the Ag atom. The rm(1) bond lengths and angles are as follows: r(Ag) 2.1800(3) Å, r(C-C) 1.2220(20) Å, r(Ag-Cl) 2.2658(3) Å and the angle H-C has the value 187.79(1)°. Ab initio calculations at the coupled-cluster singles and doubles level of theory with a perturbative treatment of triples (F12)cc-pVTZ yield a r e geometry in excellent agreement with the experimental rm(1)version, including the ethyne angular distortion.
All Science Journal Classification (ASJC) codes
- Physics and Astronomy(all)
- Physical and Theoretical Chemistry