Energy analysis of the chemical bond in group IV and V complexes: A density functional theory study

We analyzed the chemical bond between antimony, tin, titanium, and niobium chlorides with several Lewis bases using an energy partitioning analysis (EPA) and Weinhold's NBO method. The optimized geometries are in good agreement with the experimental results. The NQR-³⁵Cl frequencies appear to be fairly close to the experimental values. Theoretically obtained nuclear quadrupole coupling constants of antimony and niobium atoms are in good agreement with the experimental values. The bonding energies and experimentally known heats of formation are well reproduced by the employed level of theory. All investigated bonds in the donor-acceptor complexes are highly polar, so that the Townes-Dailey theory cannot be applied. The NBO approach shows that the donor-acceptor interactions of main-group elements such as Sb and Sn can basically be described in terms of sp hybridization, just as these interactions of the transition metal elements Ti and Nb can be described by sd hybridization.