Protonated Digermane, Distannane, and Diplumbane: Can They Be Made in the Laboratory?

The geometries, proton affinities, and relative energies of protonated digermane (Ge₂H₇⁺), distannane (Sn₂H₇⁺), and diplumbane (Pb₂H₇⁺) have been investigated by density functional theory using the correlation-consistent cc-pV nZ-PP basis sets ( n = D, T, Q). The results of the caluclations are consistent with the very limited experimental and theoretical results that are available. The lowest-lying structure of Ge₂H₇⁺ is predicted to have C₂ symmetry with a bent 3-center-2-electron Ge-H-Ge bridge, analogous to Si₂H₇⁺. For Sn₂H₇⁺ and Pb₂H₇⁺, the lowest-lying structures are predicted to be different, with a D_{3 d} structure for Sn₂H₇⁺ and a C₁ structure for Pb₂H₇⁺. The predicted proton affinities decrease in the order Pb₂H₆ (9.84 eV) > Sn₂H₆ (8.48 eV) > Ge₂H₆ (8.11 eV) > Si₂H₆ (7.72 eV) > C₂H₆ (6.18 eV). [ABSTRACT FROM AUTHOR]