Theoretical study of the dipole-bound anion (HPPH3)−

Abstract

A theoretical prediction on intermolecular monoelectron dihydrogen bond H e H in the cluster anion ( FH ) 2 {e}( HF ) 2The possibility of electron binding to the HPPH 3 and H 2 PPH 2 tautomers of diphosphine was studied at the coupled cluster level of theory with single, double, and noniterative triple excitations. The HPPH 3 tautomer, with a dipole moment of 3.7 D, binds an electron by 333 cm Ϫ1 , whereas the H 2 PPH 2 tautomer forms neither a dipole-nor valence-bound anionic state. It is suggested that the HPPH 3 tautomer, which is kinetically stable but thermodynamically unstable relative to H 2 PPH 2 , may be formed by photodetachment from the P 2 H 4 Ϫ species examined in this work. An unusual aspect of the (HPPH 3 ) Ϫ anion is that electron correlation contributes 82% to the electronic stability and effects beyond the fourth order of the Mo "ller-Plesset perturbation theory contribute 55%.

Are HBO−and BOH−electronically stable?

“…This finding is consistent with recent results for other dipole-bound species, where the correlation contributions were always crucial and very often responsible for more than 50% of the total value of D. This contribution is comparable with that found for the isoelectronic HNC À (for which the correlation effects represent $ 90% of the electron binding energy) [44]. Although the correlation effects represent more than 80% of the electron binding energy for BOH À , it should be noted that this anionic bound state exists primarily due to the long range cos =r 2 potential, which causes localization of the excess electron on the positive side of the molecular dipole (figure 1), as discussed in [12].…”

Excess Electron Attachment to Disulfide-Bridged l,l-Cystine. An ab Initio Study

“…It can be seen that in each anionic case the extra electron is localized primarily outside the molecular framework on the positive side of the molecular dipole, as it has been previously observed for other dipole-bound anions. 11,13,18,[21][22][23][24][25][26][27][28][29][30][31][32][33][34][35] The polarity of the CC neutral tautomer 10 and of the ZC and ZZ tautomers 11-13 is larger and these systems (in their neutral local minimum energy structures) exhibit dipole moments in the 7.68-15.70 D range (see Table 1). This causes the excess electron binding energies for their daugther anions to be larger (from 0.11 to 0.95 eV) as indicated in Table 2.…”

First Evidence of Rhombic (NaCl)2‐. Ab initio Reexamination of the Sodium Chloride Dimer Anion.

“…In fact, in many cases, the electron binding energy of a dipole-bound anion is dominated by the contribution from electron correlation. In particular, the dispersion interaction of the excess electron with the electrons of the neutral parent molecule proved to be crucial for the stability of the dipole-bound anion 18,19,[21][22][23][24] although higher-order correlation effects can also be significant. [21][22][23][24]29,35 An excess electron may be trapped inside a molecular cluster instead of being attached to the dipole moment of the neutral cluster.…”

“…The binding of electrons to polar molecules has been addressed in many theoretical studies. [17][18][19][20][21][22][23][24][25][26][27][28][29][30] It has been shown that, within the Born-Oppenheimer (BO) approximation, species with a dipole moment greater than 1.625 D possess an infinite number of bound anionic states. 31,32 However, a more practical critical value to experimentally observe a dipole-bound state (DBS) of anion bound by at least 1 cm -1 was found to be slightly larger, ca.…”