0000000000400280
AUTHOR
A. Jarid
Ab initio molecular orbital study of the substituent effect on ammonia and phosphine–borane complexes
Abstract The complexation energies of H 3 BXH 3− n F n ( X =N, P; n =0–3) and the proton affinities of XH 3– n F n compounds have been investigated at the G2(MP2) level of theory. The G2(MP2) results show that the phosphine complexes are more stable than the corresponding ammonia ones. Increasing fluorine substitution on nitrogen atom reduces both the basicity of NH 3− n F n and the stability of ammonia complexes. For the phosphine complexes, the successive fluorine substitution on the phosphine increase the stability of H 3 BPH 3− n F n complexes although the reduction of the basicity of the PH 3– n F n ligands with this substitution. The NBO partitioning scheme shows that the stability of…
G2(MP2) molecular orbital study of the substituent effect in the H3BPH3−nFn (n=0–3) donor–acceptor complexes
Abstract The complexation energies of H3BPH3−nFn (n=0–3) and the proton affinities of PH3−nFn compounds have been investigated at the G2(MP2) level of theory. G2(MP2) results show that the successive fluorine substitution on the phosphine increases the stability of H3BPH3−nFn complexes although the basicity of the PH3−nFn ligands reduces with this substitution. The NBO partitioning scheme shows that this stability was related to the hyperconjugation effect. It proves also that the shortening of the P–H and P–F bond lengths, upon complexation, is due to an increasing `s' character in these bonds.