Linear triatomics with noble gas-metal bonds

4 Linear triatomics with noble gas-metal bonds 

Since the turn of the present century, a series of linear complexes with the general formula NgMX (Ng = Ar, Kr, Xe M = Cu, Ag, Au X = F, Cl, Br) have been prepared and characterized by physical methods. These complexes were prepared by laser ablation of the metal from its solid and letting the resulting plasma react with the appropriate precursor. The complexes formed were then stabilized in a supersonic jet of argon gas. Characterization of these complexes was carried out mainly by microwave spectroscopy. 

Comparing the experimental and calculated Ng-M bond lengths tabulated in Table 5.8.5, it is seen that the ab initio methods adopted do reproduce this quantity very well. In order to obtain a better understanding of the nature of the Ng-M bonds, let us compare these bond lengths with values estimated from 

Optimized structures (bond lengths in pm and bond angles in degrees) and G3 heats of formation of four other N isomers. 

As shown in Table 5.8.5, the calculated Ng-M dissociation energies cover a rather wide range, from 14 kJ mol-1 in Ar-AgF to 97 kJ mol-1 in Xe-AuF. In comparison, for the aforementioned van der Waals complex Ar-NaCl, the corresponding value for the Ar-Na bond is estimated to be 8 kJ mol-1. Also, the mean Kr-F and Xe-F bond energies in KrF2 and XeF2 are 49 and 134 kJ mol-1, respectively. 

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