A computational study on [(PH2X)2]·+ homodimers involving intermolecular two-center three-electron bonds

Abstract

A computational study at CCSD(T) theoretical level has been carried out on radical cation [(PH 2 X) 2 ] Á? homodimers. Four stable minima configurations have been found for seven substituted phosphine derivatives, X = H, CH 3 , CCH, NC, OH, F and Cl. The most stable minimum presents an intermolecular two-center three-electron PÁÁÁP bond except for X = CCH. The other three minima correspond to an alternative PÁÁÁP pnicogen bonded complex, to a PÁÁÁX contact and the last one to the complex resulting from a proton transfer, PH 3 X ? :PHX Á . The complexes obtained have been compared with those of the corresponding neutral ones, (PH 2 X) 2 , and the analogous protonated ones, PH 3 X ? :PH 2 X, recently described in the literature. The spin and charge densities of the complexes have been examined. The electronic characteristics of the complexes have been analyzed with the NBO and AIM methods. The results obtained for the spin density, charge and NBO are coherent for all the complexes.

Alkylammonium Cation Affinities of Nitrogenated Organobases: The Roles of Hydrogen Bonding and Proton Transfer

“…Besides, the intermolecular distances between the H and N atoms are related to the electron density at the BCP(N⋅⋅⋅H) by an exponential expression, with a regression coefficient of R 2 =0.985, and to its Laplacian by a polynomial function (R 2 =0.854). Similar correlations were reported for related weak interactions [61–63] …”

“…Similar correlations were reported for related weak interactions. [61][62][63] Proton Affinity At this point we will discuss the relationships between ACA and PT values with the respective experimental proton affinities (Figure 13). [55,64] Whereas a poor linear correlation between the three different series of ACA (MACA, DACA and TACA) is observed (R 2 factor lower than 0.68 and large standard errors, see Supporting Information), there is an excellent correlation between the PT values and the respective proton affinity values, as the computed equations evidence (see Figure 13, bottom).…”

Super-pnicogen bonding in the radical anion of the fluorophosphine dimer

“…The radical cation has been investigated before. [34,35,36] Coupled cluster calculations describe the monocation and dication dimers 4 and 5 both as stable local minima. The first ionization requires 8.66 eV, and the second ionization another 12.95 eV, i.e.…”

Tweaking the Charge Transfer: Bonding Analysis of Bismuth(III) Complexes with a Flexidentate Phosphane Ligand

“…A relatively new congener of noncovalent interactions is the pnictogen bond (PnB), − which (in analogy with the IUPAC definition of a halogen bond) can be defined as an attractive interaction between the electron-deficient region of a pnictogen (group 15 element) called a pnictogen bond donor and a Lewis base (pnictogen bond acceptor, acting as an electron pair donor) . In the past few years, the potential of PnB in structural assembly, supramolecular architecture, anion sensing, (organo)­catalysis, and molecular recognition has also been highlighted. ,− On the basis of thorough computational studies, ,,− pnictogen bonding is chiefly electrostatic in nature (attraction between the oppositely charged regions around the two centers). Moreover, charge transfer effects (donation from the lone pair of the Lewis base into the σ*-antibonding orbitals at the pnictogen center) may also contribute, though to a much lesser extent.…”