Syntheses, formation mechanisms and structures of a series of linear diborazanes

Abstract

A series of linear diborazanes (R₁R₂R₃NBH₂NH₂BH₃, R₁, R₂, R₃ = H, Me, Et, ⁿPr, ⁱPr) have been synthesized at room temperature by the reaction of aminodiborane (ADB) with alkylamine. Theoretical calculations demonstrate that the formation mechanism of the linear diborazanes is a one-step nucleophilic reaction, where the amine molecule approaches a B atom along a line nearly colinear with a B–H_bridging bond in the ADB, and the nucleophilic reaction is controlled by thermodynamics and can occur spontaneously. The crystal structure of the linear diborazanes is affected not only by the capped alkylamine, but also by the extensive dihydrogen bonds. Both anti and gauche conformations of the linear diborazanes are observed, which are stabilized by inter-/intramolecular DHBs.