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

The geometries, proton affinities, and relative energies of protonated digermane (Ge 2 H 7 + ), distannane (Sn 2 H 7 + ), and diplumbane (Pb 2 H 7 + ) have been investigated by density functional theory using the correlation‐consistent cc‐pV n Z‐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 Ge 2 H 7 + is predicted to have C 2 symmetry with a bent 3‐center‐2‐electron Ge–H–Ge bridge, analogous to Si 2 H 7 + . For Sn 2 H 7 + and Pb 2 H 7 + , the lowest‐lying structures are predicted to be different, with a D 3 d structure for Sn 2 H 7 + and a C 1 structure for Pb 2 H 7 + . The predicted proton affinities decrease in the order Pb 2 H 6 (9.84 eV) > Sn 2 H 6 (8.48 eV) > Ge 2 H 6 (8.11 eV) > Si 2 H 6 (7.72 eV) > C 2 H 6 (6.18 eV).