Unprecedented Enhancement of Noble Gas-Noble Metal Bonding in NgAu3+ (Ng = Ar, Kr, and Xe) Ion through Hydrogen Doping.

Behavior of gold as hydrogen in certain gold compounds and a very recent experimental report on the noble gas-noble metal interaction in Ar complexes of mixed Au-Ag trimers have motivated us to investigate the effect of hydrogen doping on the Ng-Au (Ng = Ar, Kr, and Xe) bonding through various ab initio based techniques. The calculated results show considerable strengthening of the Ng-Au bond in terms of bond length, bond energy, stretching vibrational frequency, and force constant. Particularly, an exceptional enhancement of Ar-Au bonding strength has been observed in ArAuH2+ species as compared to that in ArAu3+ system, as revealed from the CCSD(T) calculated Ar-Au bond energy value of 32 and 72 kJ mol-1 for ArAu3+ and ArAuH2+, respectively. In the calculated IR spectra, the Ar-Au stretching frequency is blue-shifted by 65% in going from ArAu3+ to ArAuH2+ species. Similar trends have been obtained in the case of all Ar, Kr, and Xe complexes with Ag and Cu trimers. Among all the NgM3-kHk+ complexes (where k = 0-2), the strongest binding in NgMH2+ complex is attributed to significant enhancement in the covalent characteristics of the Ng-M bond and considerable increase in charge-induced dipole interaction, as shown from the topological analysis.