A computational study of hydrogen bonds in intermolecular systems of high complexity: arachno-pentaborane(11)···Y with Y = O2 and N 2.

The interactions of arachno-B(5)H(11) with N(2) and O(2) were theoretically studied. In the B(5)H(11)···N(2) and B(5)H(11)···O(2) complexes, the terminal hydrogens of B(5)H(11) work as electron donors whereas the bridge ones as electron acceptors. The optimized structures and the corresponding harmonic vibration spectra were investigated through the MP2/aug-cc-pVDZ level of theory. In order to characterize the hydrogen bonds, the topological calculations inherent to the QTAIM protocol and MEP analysis were carried out. The NBO analyses were useful in the interpretation of the red-shifts and blue-shifts on the stretch frequencies of the proton donors, of course in agreement with the Bent rule for the chemical bonding as well as by the conceptions of hyperconjugation or hybridization.