Quantum-chemical study of the stereoelectronic structure of 1-fluorosilatrane, 1,1-difluoroquasisilatrane, 1,1,1-trifluorohyposilatrane,and cations formed thereof

Quantum-chemical study of the electronic structure and the equilibrium geometry of the molecules X_4−n M(OCH₂CH₂) _n NH_3−n and cations X_3−n M(OCH₂CH₂) _n NH_3−n ]⁺ (M = Si, Ge; X = F, H; n = 1–3) is performed by the B3LYP method using the cc-PVDZ basis set. It is shown that for X = F the strength of the coordination bond N→M increases with the number of the cycles (n), while for X = H, on the contrary, decreases, that is, the strength of the N→M bond increases with the total electronegativity of the substituents surrounding atom M. Effect of the number of the coordination cycles on the strength of the N→M bond in the cations is negligible. The obtained results agree with the experimental data on the structure and spectral properties of the studied compounds.