The saturated five‐membered heterocyclic molecules as organic hydride donors: a computational study

Abstract

Several five‐membered heterocyclic molecules were studied theoretically as organic hydride donors. The density functional theory and ab initio methods are employed to study the direct one‐step or multistep sequence suggested for the hydride transfer from the selected molecules: H atom/electron, electron/proton/electron or electron/H atom. Out of the three multistep mechanisms, electron/H atom seems to be a probable pathway in the presence of suitable catalyst/photoreaction that can cause ionization. In the lack of such catalyst/photoreaction, the direct hydride transfer seems to be most probable with the presence of suitable hydride acceptor. A detailed mechanism of the hydride transfer from the five‐membered heterocylic compounds is important in understanding chemical and biological reactions and required for scientifically designing and synthesizing new desired five‐membered heterocyclic compounds as organic hydride donor. Copyright © 2014 John Wiley & Sons, Ltd.

A comparative theoretical study of the hydride transfer mechanisms during LiAlH 4 and LiBH 4 reductions

“…Hydride transfer is a key process in hydride reduction and so, to elucidate the associated reaction mechanism, it is important to understand the hydride reduction mechanism. In previous works, the hydride transfer mechanisms in many biological and organic reduction systems were investigated using either experimental or theoretical approaches [13][14][15][16][17][18][19][20][21][22][23][24]. Although these mechanisms have not yet been fully explained due to the variety of possible pathways involving the overall transfer of two electrons and one proton, the following hydride transfer mechanisms have been proposed: (1) direct transfer of a hydride ion (H -) in a single step, (2) two-step transfer of an electron before or after the transfer of a hydrogen atom and (3) transfer of two electrons and one proton in three separate steps.…”

“…Theoretical studies aimed at understanding the hydride transfer mechanism have also been conducted, focusing on the effects of the charge density, ionization potential and proton affinity of the reactant and transition state [13][14][15][16][17][18]21,23,24]. However, as far as we know, there are no reports of detailed charge density analysis along the reaction coordinates during hydride transfer, although it requires complete information regarding the dynamics of the mechanism.…”