Structure and Stability of Oligomeric Anions [MnX3n+1]-(M = Al, Ga, In; X = F,Cl, Br, I; n=2-4): A Quantum-Chemical Study

The structural and thermodynamic properties of oligomeric anions [MnX3n+1](-)(M = Al, Ga, In; X = F,Cl, Br, I; n = 2-4) have been obtained by the density functional theory B3LYP method with the LAN2DZ(d) and LAN2DZ( d)+ basis sets. A wide diversity of structural isomers was found for trimeric fluoride anions M3F10-. Among the trimers, except In3F10-, the most stable is a linear isomer composed of two MX3 molecules coordinated to the M anion. The formation of tetrameric anions MX4 (-)was demonstrated to be thermodynamically allowed at low temperatures at MX3 : X- > 4 : 1. The existence of higher oligomers is less probable. The affinity of oligomer halides (MX3)(n) for halide ions increases with an increase in n. The propensity to form oligomeric anions decreases in the series F > Cl >= Br > I. The fluoride systems show a tendency to form structures with CN = 5 and 6, these structures for In being the most stable.