Thermal and photolytic reactions of gallium and indium atoms (M) and their dimers M2 with carbon monoxide in low-temperature matrices:: Formation of terminal, bridged, and ionic carbonyl derivatives

Infrared spectroscopy has been used to chart the thermal reactions occurring following co-deposition of gallium or indium vapors with carbon monoxide-doped argon at ca. 12 K, as well as the reactions subsequently induced by irradiating the resulting matrix with UV light (lambda = 200-400 nm). Following deposition, the molecules GaCO, InCO, Ga . GaCO, In . InCO, GaO(mu-CO)Ga, Ga(CO)(2), In(CO)(2), and In(CO)(2). In were generated. Under the action of UV light, the Ga/CO system gives rise to the new gallium carbonyl Ga(mu-CO)(2)Ga. Under similar conditions, the complex In+[C2O2](.-) is formed as a result of significant charge transfer between the metal and the CO ligands and with the concomitant linking together of two such ligands via a C-C bond. Assignments of the absorption bands are made and the products characterized on the basis of C-13 substitution and by comparison with the vibrational properties of known carbonyl derivatives or with those forecast for novel species by DFT calculations.