AIM and ELF Electronic Structure/G2 and G3 π-Bond Energy Relationship for Doubly Bonded Silicon Species, H₂SiX (X = E¹⁴H₂, E¹⁵H, E¹⁶)¹

π-Bond energies in doubly bonded silicon species, H2SiX (X = E14H2, E15H, E16), were determined using G2 and G3 procedures. In addition, the distribution of electron density in the internuclear area between silicon and the element in H2SiX and H3Si−XH was estimated using quantum-topological approaches AIM (MP2/6-311++G(2d,p)) and ELF (HF/6-311++G(2d,p)). Both parameters, an increase of electron density at the critical point of the silicon−element bond and π-bond energy, appeared to correlate linearly, increasing on going from group 14 to group 16 elements. The contribution of the ion-component to the SiE π-bond energy increases as the negative inductive effect of the element grows, attaining the maximum for silanone.