Journal of Physical Chemistry A, Vol.112, No.47, 12187-12195, 2008
Electronic Structure of Germanium Monohydrides GenH, n=1-3
Quantum chemical calculations were applied to investigate the electronic structure of germanium hydrides, GenH (n = 1, 2, 3), their cations, and anions. Computations using a multiconfigurational quasi-degenerate perturbation approach (MCQDPT2) based on complete active space wave functions (CASSCF), multireference perturbation theory (MRMP2), and density functional theory reveal that Ge2H has a B-2(1) ground state with a doublet-quartet gap of similar to 39 kcal/mol. A quasidegenerate (2)A(1) state has been derived to be 2 kcal/mol above the ground state (MCQDPT2/aug-cc-pVTZ). In the case of the cation Ge3H+ and anion Ge3H-, singlet low-lying electronic states are derived, that is, (1)A' and (1)A(1), respectively. The singlet-triplet energy gap is estimated to 6 kcal/mol for the cation. An "Atoms in Molecules" (AIM) analysis shows a certain positive charge on the Ge, (n = 1, 2, 3) unit in its hydrides, in accordance with the NBO analysis. The topologies of the electron density of the germanium hydrides are different from that of the lithium-doped counterparts. On the basis of our electron localization function (ELF) analysis, the Ge-H bond in Ge2H is characterized as a three-centertwo-electron bond. Some key thermochemical parameters of GenH have also been derived.