An Isolated Complex of Ethyne and Gold Iodide Characterized by Broadband Rotational Spectroscopy and Ab initio Calculations

Abstract

A molecular complex of C2H2 and AuI has been generated and isolated in the gas phase through laser ablation of a gold surface in the presence of an expanding sample containing small percentages of C2H2 and CF3I in a buffer gas of argon. Rotational, B0, centrifugal distortion, ΔJ and ΔJK, and nuclear quadrupole coupling constants, χaa(Au), χbb(Au) - χcc(Au), χaa(I), and χbb(I) - χcc(I), are measured for three isotopologues of C2H2···AuI through broadband rotational spectroscopy. The complex is C2v and T-shaped with C2H2 coordinating to the gold atom via donation of electrons from the π-orbitals of ethyne. On formation of the complex, the C≡C bond of ethyne extends by 0.032(4) Å relative to r(C≡C) in isolated ethyne when the respective r0 geometries are compared. The geometry of ethyne distorts such that ∠(*-C-H) (where * indicates the midpoint of the C≡C bond) is 194.7(12)° in the r0 geometry of C2H2···AuI. Ab initio calculations at the CCSD(T)(F12*)/AVTZ level are consistent with the experimentally determined geometry and further allow calculation of the dissociation energy (De) as 136 kJ mol(-1). The χaa(Au) and χaa(I) nuclear quadrupole coupling constants of AuI and also the Au-I bond length change significantly on formation of the complex consistent with the strong interaction calculated to occur between C2H2 and AuI.

π⋅⋅⋅H+⋅⋅⋅π Hydrogen Bonds and Their Lithium and Gold Analogues: MP2 and CASPT2 Calculations

“…A theoretical study on the resonance character of bonding in B ⋅⋅⋅ M−X systems (M=Cu, Ag, Au; X=F, Cl, Br, CH 3 , CF 3 ; B=CO, H 2 O, H 2 S, C 2 H 2 , C 2 H 4 ) is partly in line with this study, since among different interactions also the Au ⋅⋅⋅ π contacts are considered here . One can also mention the T‐shaped FLi ⋅⋅⋅ C 2 H 4 and IAu ⋅⋅⋅ C 2 H 2 structures, the latter of which was analyzed both theoretically and experimentally by broadband rotational spectroscopy . Several examples are more or less related to this study: the association reactions leading to Ag + ⋅⋅⋅ C 2 H 2 and Ag + ⋅⋅⋅ (C 2 H 2 ) 2 , which were studied by high‐pressure mass spectrometry, the analysis of crystal structures in which Ag + ⋅⋅⋅ (C 2 H 2 ) n ( n ≤4) clusters were detected with T‐shaped Ag + ⋅⋅⋅ C 2 H 2 arrangements, and earlier experimental studies on the Ag(C 2 H 4 ) 3 + ions in the solid state …”

“…[20] One can also mention the T-shaped FLi···C 2 H 4 [21] andI Au···C 2 H 2 structures, the latter of which was analyzed both theoretically and experimentally by broadband rotational spectroscopy. [22] Several examples are more or less related to this study:t he association reactions leading to Ag + ···C 2 H 2 and Ag + ···(C 2 H 2 ) 2 ,w hich were studied by high-pressurem ass spectrometry, [23] the analysis of crystal structuresi nw hichA g + ···(C 2 H 2 ) n (n 4) clusters were detected with T-shaped Ag + ···C 2 H 2 arrangements, [24] and earlier experimental studies on the Ag(C 2 H 4 ) 3 + ions in the solid state. [25] The ab initio calculations were supported by the Quantum Theoryo fA tomsi nM olecules [26] and energy decomposition analysis( EDA) [27,28] to deepen the understanding of the nature of the interactions in these systems.…”

Theoretical investigation on the nature of substituted benzene⋯AuX interactions: covalent or noncovalent?

“…Computational evidence was also given for the possibility of the existence of stable HFÁ Á ÁAu-OH and H 2 OÁ Á ÁAu-OH complexes. 16 Legon and coworkers [17][18][19][20][21][22][23] characterized a series of complexes BÁ Á ÁMX (B = N 2 , C 2 H 2 , C 2 H 4 , (CH 2 ) 3 , H 2 O, H 2 S, PH 3 , or NH 3 ; M = Cu, Ag, Au; X = F, Cl, Br) by means of rotational spectroscopy and ab initio calculations, and found that the BÁ Á ÁMX complexes are isomorphous with the hydrogen-or halogen-bonded counterparts, and exhibit some similar properties with hydrogen bonds. The name 'coinage-metal' noncovalent bond 23 was suggested for the non-covalent interaction in BÁ Á ÁMX, by analogy with hydrogen and halogen bonds.…”

Geometries of H2S⋯MI (M = Cu, Ag, Au) complexes studied by rotational spectroscopy: The effect of the metal atom

“…Contributions to the calculated ab initio geometry of AuI were discussed in detail in a previous work. 58 It was shown that extrapolation beyond CCSD(T)(F12*)/AVTZ to the basis set limit does not yield a significant change in the r(AuI) distance calculated for free AuI. However, the inclusion of core-valence correlation reduces this bond length by 0.014 Å.…”