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Study of the Electronic Structure of Molecules. VI. Charge-Transfer Mechanism for the NH3+HCl⇆NH4Cl Reaction

1967; American Institute of Physics; Volume: 47; Issue: 7 Linguagem: Inglês

10.1063/1.1703314

1520-9032

E. Clementi,

Gas Sensing Nanomaterials and Sensors

In the NH3+HCl⇆NH4Cl reaction, analyzed via the population-analysis method, we have determined that the nitrogen atom is capable of receiving pseudo-π electrons from the hydrogens of the NH3 molecule and to transfer an equivalent amount of σ electrons to the chlorine atom. This π-electron charge donated originally by the hydrogens, then accepted by nitrogen and finally donated by nitrogen as σ charge goes to the Cl atom. The hydrogen atom of HCl donates parts of its σ electronic charge to the Cl atom. Thus, the chlorine atom accepts σ electrons from the hydrogen of HCl and σ electrons from the nitrogen. Therefore, in addition to the familiar concepts of charge ``donor'' and ``acceptor'' we can make use of the concepts of charge ``transformer'' and charge ``dispatcher.'' The efficiency of the transformer is the ratio of the accepted charges of a given symmetry and the donated charges of a different symmetry. In the NH3+HCl reaction, the nitrogen atom is a π→σ transformer with nearly unit efficiency. The reaction NH3+HC⇆NH4Cl can be summarized as the process where the H3 group (of NH3) is π donor, the N atom is σ→π transformer (σ donor and π acceptor), the H (of HCl) is a charge dispatcher (transfer the σ charge of N to the Cl atom) and σ donor, and finally, the Cl atom is a σ acceptor. During the entire process the nitrogen atom has nearly constant charge of eight electrons.