Structure, bonding and formation of molecular germanium oxides, hydroxides and oxyhydroxides

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Molecular germanium oxides, hydroxides and oxyhydroxides were studied by means of density functional theory. The polymerization reactions of GeO and GeO 2 were found exothermic up to the tetramer, and possible product structures were characterized. Important features are the instability of larger ring structures, and how Ge 2O 2 rings become important building blocks, independently on whether the long-range order resembles clusters or chains. This unit is proposed to provide a clue to the unknown bulk structure of GeO(s). Water additions to both (GeO) n and (GeO 2) n polymers are investigated. The reactions with GeO bonds are found exothermic by 230–250 kJ/mol, while similar water additions to Ge–O–Ge bridges are exothermic only when reacting with one of the bridges in the strained Ge 2O 2 ring. Reactions with larger clusters as well as further fragmentation are found slightly endothermic. The most stable product of water addition to Ge 2O 4 is (HO) 3GeOGe(OH) 3, which has one Ge–O–Ge bridge and two intramolecular hydrogen bonds. In addition, structures and stabilities of the `odd' oxides Ge 2O, Ge 2O 3, Ge 3O 4 and GeO 3 are investigated.