Quantum-Chemical Study of the Structure and Stability of Gallium Hydride Oligomers

General trends in variation of the structure and stability of different gallium hydride oligomers with tetra-, penta-, and hexacoordinated gallium atoms are studied by means ab initio quantum-chemistry calculations with the use of a polarized split-valence basis set. The regularities in variation of the relative stability of oligomers of (GaH(3))(n) are found to be quite different from those of related (AlH(3))(n) clusters. For gallium hydride, cyclic structures with tetracoordinated metal atoms are the most stable, while compounds with penta- and hexacoordinated gallium atoms have significantly higher energies, and their structures often do not correspond to local minima of the potential energy surface. For this reason, the oligomerization process for GaH(3) should differ from that for AlH(3); namely, it should lead to small cyclic clusters rather than to the crystalline structure with hexacoordinated metal atoms.