Access to metastable [GeH2]n materials via a molecular “bottom-up” approach

Computations were
performed with the Gaussian16 software. For the computational determination of
reaction coordinates for the reaction of Ge(OtBu)2 ­with
HBpin and for relative energies of the ImMe2•Ge(OR)2
analogues geometry optimizations, using default convergence criteria, were
performed using density functional theory (DFT) with the M06-2X functional and the cc-pVTZ
basis set was used. Harmonic vibrational analyses were performed at the same level of
theory for all optimized stationary points to determine their character
(minimum or first-order saddle point) and to acquire the thermochemical data
(at 298.15 K).

In keeping with recent computational studies of long-chain
Ge species, the geometry optimizations of the oligomerized isomers of [GeH2]n
(n = 1-5) and the linear H-(GeH2)10-H and branched H-[Ge(H)(GeH3)]5-H
isomers were performed using density functional theory (DFT) with the PBE
functional, the cc-pVTZ basis set, and an empirical dispersion correction GD3BJ. Harmonic vibrational analyses were
performed at the same level of theory for all optimized stationary points to
determine their character (minimum or first-order saddle point) and to acquire
the thermochemical data (at 298.15 K).

Time-dependent density function theory (TD-DFT) computations
were carried out on the linear H-(GeH2)10-H and branched
H-[Ge(H)(GeH3)]5-H isomers using the B3LYP functional and the
cc-pVTZ basis set, with five triplet and 5 singlet excitations resolved. IR and Raman frequency
calculations were carried out using density functional theory (DFT) with the
B3LYP functional and cc-pVDZ basis set.