Theoretical study of Si3H3+ and Ge3H3+ isomers

Five stable cyclic structures of Si3H3+ and of Ge3H3+ have been studied with the G2 molecular orbital method. For both Si3H3+ and Ge3G3+, the global minimum is predicted to have the cyclopropenyl structure of D3h symmetry, lying 28.1 and 3.8 kcal mol−1 below the hydrogen-bridged C3v structure, respectively. On the other hand, B3LYP density functional theory calculations predict the latter structure of Ge3H3+ to lie below the former energetically. However, the present work provides no definite evidence as to which method is giving the correct result.