Potential energy surface and thermochemistry for the direct gas phase reaction of germane and water

Gas phase reaction between germane GeH4 and water H2O was investigated at CCSD(T)/[aug-cc-pVTZ-pp for Ge + Lanl2dz for H and O]//MP2/6-31G(d,p) level. Only the hydrogen elimination channels are monitored. Within the energy range of 100 kcal/mol, we located nine equilibrium and six transition states on the potential energy surface (PES) of the Ge–O–H systems. GeH4 reacts with H2O exothermically (by 2.37 kcal/mol) without a barrier to form a non-planar complex GeH4·H2O which isomerizes to GeH3OH·H2 and H2GeOH2·H2 with a barrier of 44.34 kcal/mol and 53.75 kcal/mol respectively. The first step of hydrogen elimination gives two non-planar species, GeH3OH and H2GeOH2 but germinol GeH3OH is found to be more stable. Further thermal decomposition reactions of GeH3OH involving hydrogen elimination have been studied extensively using the same method. The final hydrogen elimination step gives HGeOH which can exist in cis and trans forms. As the trans form is more stable, only the trans form is considered on the potential energy surface (PES) of the reaction. The important thermochemical parameters (∆rEtot + ZPE), ∆rH and ∆rG for the H2 elimination pathways are predicted accurately.