Distortion of ethyne on coordination to silver acetylide, C{sub 2}H{sub 2}⋅⋅⋅AgCCH, characterised by broadband rotational spectroscopy and ab initio calculations
The rotational spectra of six isotopologues of a complex of ethyne and silver acetylide, C{sub 2}H{sub 2}⋅⋅⋅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% C{sub 2}H{sub 2}, 1% SF{sub 6}, and 98% Ar undergoing supersonic expansion. Rotational, A{sub 0}, B{sub 0}, C{sub 0}, and centrifugal distortion Δ{sub J} and Δ{sub JK} constants are determined for all isotopologues of C{sub 2}H{sub 2}⋅⋅⋅AgCCH studied. The geometry is planar, C{sub 2v} and T-shaped in which the C{sub 2}H{sub 2} sub-unit comprises the bar of the “T” and binds to the metal atom through its π electrons. In the r{sub 0} geometry, the distance of the Ag atom from the centre of the triple bond in C{sub 2}H{sub 2} 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 C{sub 2}H{sub 2} sub-unit, are determined to be 1.2200(24) Å and 186.0(5)°, respectively. This distortion of the linear geometry of C{sub 2}H{sub 2} involves the hydrogen atoms moving away from the silver atom within the complex. The results thus reveal that the geometry of C{sub 2}H{sub 2} changes measurably on coordination to AgCCH. A value of 59(4) N m{sup −1} is determined for the intermolecular force constant, k{sub σ}, confirming that the complex is significantly more strongly bound than hydrogen and halogen-bonded analogues. Ab initio calculations of the r{sub e} geometry at the CCSD(T)(F12{sup *})/ACVTZ level of theory are consistent with the experimental results. The spectra of the {sup 107}Ag{sup 13}C{sup 13}CH and {sup 109}Ag{sup 13}C{sup 13}CH 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.
- OSTI ID:
- 22253386
- Journal Information:
- Journal of Chemical Physics, Vol. 140, Issue 12; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-9606
- Country of Publication:
- United States
- Language:
- English
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