Optimized structures and ring strain energies of isoelectronic homo- and heterogermiranes c-AX2GeH2GeH2q (A/q = Ga/−1, Ge/0, As/+1): Variable trends across triads

Ring strain energies (RSEs) estimated for a series of isoelectronic three-membered ring homo- and heterogermiranes c-AX2GeH2GeH2q (A/q = Ga/–1, Ge/0, As/+1; X = H, Me, F, t-Bu) fall into three categories. Those where the X substituent is small, and neutral or an electron donor (H, Me), show v-shaped trends in RSE. Quantum Theory of Atoms In Molecules (QTAIM) calculations suggest this arises because the charged rings have the greatest difference between bond lengths and bond path distances, the latter being the paths of most significant electron density. However, when X is large (t-Bu), the trend is to decreasing RSEs across the triad. This arises because of the behavior of the chain molecules used in the RSE calculation. When X is electron withdrawing (F), the trend is to increasing RSEs across the triad. This arises because the chain molecules used to calculate RSE exhibit extremely large Ge–A–Ge angles.