Distortions of ethyne when complexed with a cuprous or argentous halide: the rotational spectrum of C2H2⋯CuF

Daniel P. Zaleski, Susanna L. Stephens, David P. Tew, Dror M. Bittner, Nicholas R. Walker*, Anthony C. Legon

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

19 Citations (Scopus)


A new molecule C2H2⋯CuF has been synthesized in the gas phase by means of the reaction of laser-ablated metallic copper with a pulse of gas consisting of a dilute mixture of ethyne and sulfur hexafluoride in argon. The ground-state rotational spectrum was detected by two types of Fourier-transform microwave spectroscopy, namely that conducted in a microwave Fabry-Perot cavity and the chirped-pulse broadband technique. The spectroscopic constants of the six isotopologues 12C2H263Cu19F, 12C2H265Cu19F, 13C2H263Cu19F, 13C2H265Cu19F, 12C2D263Cu19F and 12C2D265Cu19F were determined and interpreted to show that the molecule has a planar, T-shaped geometry belonging to the molecular point group C2v, with CuF forming the stem of the T. Quantitative interpretation reveals that the ethyne molecule is distorted when subsumed into the complex in such manner that the C≡C bond lengthens (by δr) and the two H atoms cease to be collinear with the C≡C internuclear line. The H atoms move symmetrically away from the approaching Cu atom of CuF, to increase each ∗≡C-H angle by δA = 14.65(2)°, from 180° to 194.65(2)°. Ab initio calculations at the explicitly-correlated level of theory CCSD(T)(F12∗)/aug-cc-pVTZ lead to good agreement with the experimental geometry. It is shown that similar distortions δr and δA, similarly determined, for four complexes C2H2⋯MX (M = Cu or Ag; X = F, Cl or CCH) are approximately linearly related to the energies De for the dissociation process C2H2⋯MX = C2H2 + MX.

Original languageEnglish
Pages (from-to)19230-19237
Number of pages8
JournalPhysical Chemistry Chemical Physics
Issue number29
Publication statusPublished - 7 Aug 2015


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