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Distortion of ethyne on coordination to silver acetylide, C2H2⋅⋅⋅AgCCH, characterised by broadband rotational spectroscopy and ab initio calculations

Lookup NU author(s): Dr Su Stephens, Dr Daniel Zaleski, Dr Nick Walker, Professor Anthony Legon



This is the final published version of an article that has been published in its final definitive form by American Institute of Physics, 2014.

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The rotational spectra of six isotopologues of a complex of ethyne and silver acetylide, C2H2⋅⋅⋅AgCCH, are measured by both chirped-pulse and Fabry-Perot cavity versions of Fourier-transform microwave spectroscopy. The complex is generated through laser ablation of a silver target in the presence of a gas sample containing 1% C2H2, 1% SF6, and 98% Ar undergoing supersonic expansion. Rotational, A 0, B 0, C 0, and centrifugal distortion Δ J and Δ JK constants are determined for all isotopologues of C2H2⋅⋅⋅AgCCH studied. The geometry is planar, C2v and T-shaped in which the C2H2 sub-unit comprises the bar of the “T” and binds to the metal atom through its π electrons. In the r 0 geometry, the distance of the Ag atom from the centre of the triple bond in C2H2 is 2.2104(10) Å. The r(HC≡CH) parameter representing the bond distance separating the two carbon atoms and the angle, ∠(CCH), each defined within the C2H2 sub-unit, are determined to be 1.2200(24) Å and 186.0(5)°, respectively. This distortion of the linear geometry of C2H2 involves the hydrogen atoms moving away from the silver atom within the complex. The results thus reveal that the geometry of C2H2 changes measurably on coordination to AgCCH. A value of 59(4) N m−1 is determined for the intermolecular force constant, k σ , confirming that the complex is significantly more strongly bound than hydrogen and halogen-bonded analogues. Ab initio calculations of the r e geometry at the CCSD(T)(F12*)/ACVTZ level of theory are consistent with the experimental results. The spectra of the 107 Ag 13C13CH and 109 Ag 13C13CH isotopologues of free silver acetylide are also measured for the first time allowing the geometry of the AgCCH monomer to be examined in greater detail than previously.

Publication metadata

Author(s): Stephens SL, Zaleski DP, Mizukami W, Tew DP, Walker NR, Legon AC

Publication type: Article

Publication status: Published

Journal: Journal of Chemical Physics

Year: 2014

Volume: 140

Issue: 12

Print publication date: 28/03/2014

Online publication date: 25/03/2014

Acceptance date: 26/02/2014

Date deposited: 08/04/2014

ISSN (print): 0021-9606

ISSN (electronic): 1089-7690

Publisher: American Institute of Physics


DOI: 10.1063/1.4868035


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Funder referenceFunder name
European Research Council (UK)
Leverhulme Trust
Royal Society for a University Research Fellowship
University of Bristol
IIF-301616Marie Curie Fellowship