Triplet germylenes with separable minima at ab initio and DFT levels

Abstract

Six ground state triplet germylenes, with HGeX and GeX 2 formulae, are reached at QCISD(T)/6-311++G** and B3LYP/6-311++G** levels of theory (X = Li, Na, and K). Their corresponding less stable electronic isomers appears as singlet germylene minima. Scanning Ф as a function of energy for every triplet species gives two energy minima, separated by significant energy barriers. The same scanning gives merely one minimum for most singlet species, at the potential energy hyper-surface. Thus, only the open-shell (σ 1π 1) triplet states exhibit bond-angle isomerism, since no such isomers could be found for the (σ 2π 0) singlet states except for singlet GeLi 2 which shows a possible covalent bonding interaction between the two Li atoms. All triplet X Ge X species appear more linear than their corresponding triplet H Ge X. As the electro-positivity of X increases, the Ge X bond distances in all species lengthen, while their singlet–triplet energy separations (Δ E s–t) decrease, with the lowest Δ E s–t given for H Ge K. The Δ E LUMO–HOMO for singlet HGeX and GeX 2 species appear inversely proportional to the size of X, showing a trend of K > Na > Li. Interestingly, for both singlet HGeX and GeX 2 species, linear correlations are found between the Δ E LUMO–HOMO and their corresponding Δ E s–t,X.