Energy decomposition analysis of cationic carbene analogues with group 13 and 16 elements as a central atom: a comparative study.

Decomposition of the molecular interaction energies into physically intuitive components provides insight to the chemical bonding between fragments. Extended transition state-natural orbital for chemical valence (ETS-NOCV) and natural energy decomposition analysis (NEDA) are methodologically different schemes to partition the interaction energies into physically similar components. To answer the question if the two energy decomposition analysis (EDA) schemes render the same interpretations of reactions, both schemes are employed to study the reactions of two cationic carbene analogues: (1) bis(tri- tert -butylphosphane) group-13-element monocations [(P t Bu 3 ) 2 M + (M = B, Al, Ga, In, and Tl)] and (2) N-heterocyclic carbene (NHC) dications with a group 16 element as the central atom [(Dipp 2 DAB)M 2+ , M = O, S, Se, and Te; Dipp 2 DAB = 1,4-(2,6-diisopropyl)phenyl-1,4-diaza-1,3-butadiene]. Comparison of the EDA components obtained using the ETS-NOCV and NEDA schemes suggests that, for each individual reaction, the two EDA schemes may not necessarily lead to a consensus about the interpretation or "understanding" of the reaction. However, if the whole families of the studied cationic carbene analogue reactions with simple hydrocarbons are considered, the ETS-NOCV and NEDA schemes agree that the most dominant effects on the interaction energies are the orbital interactions, with the second most dominant being electrostatics, and Pauli exclusions being the least effective.