QUANTUM CHEMITRY STUDY ON STRUCTURES, ACTIVITIES AND REACTIONS OF ONIUM-BORONIUM DICATIONS

Abstract

This paper provides information about theoretical investigations of structures of onium-boronium dications X⁺BH₃⁺, X⁺BH₅⁺; (X= NH₃, PH₃, H₂O, H₂S) and some reactions of them in thermodynamic control and kinetic control. Two kinds of reactions studied are complexation of onium-boronium dications X⁺BH₃⁺ with H₂ leading to X⁺BH₅⁺ and  deprotonation of  X⁺BH₅⁺  to give X⁺BH₄. The similar studies with boronium ion analog BH₄⁺ and BH₆⁺ is carried out and results obtained pointed out that the eletrophility of onium-boronium dications is more stronger than that of boronium ion: onium-boronium dications X⁺BH₃⁺, X⁺BH₅⁺ are superelectrophiles. The structures of onium-boronium dications and boronium ions are optimized by using ab initio methods at the MP2/6-311+G** level of Gaussian 03W, revision B.04 and represented with Gaussview 3.0. Frequency calculation is performed to assure the obtained structures corresponding to minimun energies and have no any imaginary frequency. The transition structures are calculated and verified due to Intrinsic Reaction Coordinate Calculations. The properties of structures, as MP2 energy, Gibbs free energy, activation energy are also  examined.