The noncovalent complexes of nido-C4B2H6 with H2O,CH3 OH and NH3 Lewis bases: A Theoretical study

Quantum chemical calculations at the MP2/6-311++G(2d,2p) level of theory were used to examine the complexes resulting from the interactions between C 4 B 2 H 6 and HY Lewis bases ( HY = NH 3 , H 2 O , and CH 3 OH molecules). Four different directional geometries could be obtained for C 4 B 2 H 6 -HY complexes.The complexes with conformation A had (B11-H12 · · · H-Y) dihydrogen bond and C-H meta … YH hydrogen bond interactions. In structure B, HY from the pentagonal basal plane interacted with carborane molecule. In conformation C, HY had DHB and HB interactions with peripheral B-H and C-H ortho bonds of the carborane backbone. Finally, conformation D had only hydrogen bond interaction between HY with C-H meta bonds of the C 4 B 2 H 6 . Among all the complexes resulting from the interaction of HY with C 4 B 2 H 6 , the greatest interaction energy belonged to the complexes with configurations B. The Bader’s Quantum Theory of Atoms in Molecules (QTAIM) was used to analyze the optimized complexes. Molecular electrostatic potentials (MEP), vibrational frequencies and molecular energies (HOMO and LUMO) were also calculated for these clusters. Graphical abstract Synopsis There are various orientations for C 4 B 2 H 6 to interact with both Lewis acids and bases. According to the minimal molecular electrostatic potential (MEP) calculations, the highest electron density is concentrated on the B-H bonds while the lowest one is on the C-H bonds. On the other hand, the basal plane of the C 4 B 2 H 6 has both abilities, in a way that the most stable complex is achieved when the basal plane interacts with the target molecules.