Theoretical study of B 2H n, (with n=2 to 6): molecules and related positive ions

Abstract

In this work B 2H n molecules and the related positive ions B 2H n + (with n = 2 to 6 ) are studied. Some geometrical structures of these compounds have been determined at the Hartree-Fock and CISD levels. As already mentioned, large basis sets are required to predict correctly the nature of the stationary points. The Boys' localization procedure was used to describe the electron distribution. The BHB bridged bond appears to be a three-centre two-electron bond. In borane derivatives from two to six electrons are found in the central BB bond. Vibrational frequencies and statistical thermodynamics allow values for thermal corrections, standard entropy and heat capacity to be proposed. Estimation of the total energies at the MP 4 (SDTQ) level for 6–31 + G ** (2 d, f) basis set leads to predict the heats of formation of B 2H 6, B 2H 5, B 2H 5 +, B 2H 4, B 2H 4 +, B 2H 3, B 2HH 3 + , B 2H 2 and B 2HH 2 +.