Nonclassical B-HbMIDLINE HORIZONTAL ELLIPSISπ interaction in diboraneMIDLINE HORIZONTAL ELLIPSISlocalized-π sandwiches: A DFT-D3 study

The study presents a quantitative estimation of B-HbMIDLINE HORIZONTAL ELLIPSIS pi interaction in diborane-localized-pi half sandwiches and sandwiches. DFT-D3 method is used for geometry optimization and estimating the stability of the complexes (in terms of stabilization energies). The diborane molecule is the source of bridging hydrogen and O-2, C2H4, and C2H2 molecules are considered as the localized pi-systems. MP2 and CCSD(T) calculations are also performed to measure the stability of the chosen complexes. Results indicate that the complexes are feebly stable in gas phase with stabilization energies <5.0 kcal mol(-1). Compared to DFT-D3 functionals, MP2 calculations are found to be more suitable in predicting the stability of the complexes. Dispersive interaction is the primary mode of interaction in stabilizing the complexes. Presence of substituents either on diborane or on the considered pi-systems play key role in stabilizing the complexes. Thermochemical analysis demonstrates the exothermic nature of complexation. H-1 and B-13 NMR analysis are also performed.