The gas-phase ion chemistry of phosphine has been investigated by ab initio theoretical calculations and experimental techniques. Following a previous study of H and H2 loss pathways from the 3P–PH3+ adduct (generated by 3P+ reacting with PH3), the quantum chemical study of these processes has been extended to the ion–molecule reactions starting from 2PH+ reacting with PH3, as observed by ion trapping. In these experiments, PH+ reacts to give P2Hn+ (n = 2,3) product ions, with loss of H2 or H in different pathways, and also reacts in charge–exchange processes to form PH and PH3+. Moreover, elimination of two hydrogen molecules has been observed leading to the formation of the P2+ ion species. All these processes take place at similar rates, their constants ranging from 1.2 to 5.5×10−10 cm3 molecule−1 s−1. The geometrical structures and energies of transition structures, reaction intermediates, and final products have been determined by ab initio theoretical methods. The initial step is formation of the 2HP–PH3+ adduct. Then, a hydrogen atom can be directly lost either from dicoordinated or tetracoordinated phosphorus, to give 3P–PH3+ or 1HP�PH2+, respectively. Alternatively, one hydrogen can first undergo a displacement from the latter to the former P atom to give 2H2P–PH2+. This migration can then be followed by P–H bond dissociation, yielding again 1HP�PH2+. Dissociation of H2 can also occur, from either the initial HPPH3+ or rearranged H2P–PH2+ isomeric ions, yielding the 2HP�PH+ or 2H2P�P+ ions, respectively. These last species are related by a H-migration process. A last H2 loss from H2P�P+ produces 2P2+. Other pathways were explored, but proved not to be viable. The heats of formation of the P2Hn+ (n = 0–4) ionic species have also been computed and reported with the experimental data in the literature.

Gas phase ion chemistry and ab initio theoretical study of phosphine. II. Reactions of PH+ with PH3

ANTONIOTTI, Paola;OPERTI, Lorenza;RABEZZANA, Roberto;TONACHINI, Glauco;VAGLIO, Gian Angelo
1998

Abstract

The gas-phase ion chemistry of phosphine has been investigated by ab initio theoretical calculations and experimental techniques. Following a previous study of H and H2 loss pathways from the 3P–PH3+ adduct (generated by 3P+ reacting with PH3), the quantum chemical study of these processes has been extended to the ion–molecule reactions starting from 2PH+ reacting with PH3, as observed by ion trapping. In these experiments, PH+ reacts to give P2Hn+ (n = 2,3) product ions, with loss of H2 or H in different pathways, and also reacts in charge–exchange processes to form PH and PH3+. Moreover, elimination of two hydrogen molecules has been observed leading to the formation of the P2+ ion species. All these processes take place at similar rates, their constants ranging from 1.2 to 5.5×10−10 cm3 molecule−1 s−1. The geometrical structures and energies of transition structures, reaction intermediates, and final products have been determined by ab initio theoretical methods. The initial step is formation of the 2HP–PH3+ adduct. Then, a hydrogen atom can be directly lost either from dicoordinated or tetracoordinated phosphorus, to give 3P–PH3+ or 1HP�PH2+, respectively. Alternatively, one hydrogen can first undergo a displacement from the latter to the former P atom to give 2H2P–PH2+. This migration can then be followed by P–H bond dissociation, yielding again 1HP�PH2+. Dissociation of H2 can also occur, from either the initial HPPH3+ or rearranged H2P–PH2+ isomeric ions, yielding the 2HP�PH+ or 2H2P�P+ ions, respectively. These last species are related by a H-migration process. A last H2 loss from H2P�P+ produces 2P2+. Other pathways were explored, but proved not to be viable. The heats of formation of the P2Hn+ (n = 0–4) ionic species have also been computed and reported with the experimental data in the literature.
109
10853
10863
P. Antoniotti; L. Operti; R. Rabezzana; G. Tonachini; G.A. Vaglio
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/2318/110140
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