The interaction of 1,2-dihyciro-1,2-, 1,3-dihydro-1,3- and 1,4-dihydro-1,4-azaborine isomers with one and two water molecules has been studied using a variety of supermolecular (Moller-Plesset = MP, and coupled cluster = CC) as well as perturbational (symmetry-adapted perturbation theory = SAPT) electron-correlation methods in the complete basis-set limit. It has been found that the water molecule binds to azaborine isomers through O-H center dot center dot center dot pi, pi-H center dot center dot center dot O, and dihydrogen bonding linkages. The SAPT interaction energy decomposition shows that these complexes are mostly stabilized by dispersion followed closely by induction contributions. Pauli repulsion hinders water molecule to be polarized by azaborine in the O-H center dot center dot center dot pi type of complexes. According to the interacting-quantum-atoms analysis, the structures with a primary binding of the O-H center dot center dot center dot pi type benefit from an additional stabilization factor resulting from: the interaction of the oxygen and the second hydrogen atom of water, i.e., the one which does not point toward the ring, while the interaction of hydrogens from water with azaborines plays a destabilizing role for the pi-H center dot center dot center dot Omicron type. The same method states that the intermolecular bindings between azaborines and the water molecule have a multicenter character with a small bond polarization, and they are classified as closed-Shell (noncovalent) by quantum theory of atoms-in-molecules analysis at bond critical points. The complexes of azaborines with two water molecules tend to arrange in a circular fashion with a recognizable water dirtier attached to the azaborine molecule. A comparison with the CCSD(T) benchmarks shows that the noriadditive contribution to the interaction energy of the trimers is negative and with a good accuracy. can be accounted for by the MP2 method. A good agreement between Hartree-Fock (HP) and MP2 nonadditive energy, as well as the decomposition of HP: nonadditive interaction energies divulge the importance of nonadditive induction energy in the trimers. The interaction energies for the azaborine with one water calculated with the SAPT(DFT), MP2, SCS-MP2, and MP2C methods are in satisfactory agreement with each other. Finally, it has been found that the population analysis from the electron localization function offers the most comprehensive explanation of the orientational preferences of the water molecule in the complex.
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