Pnicogen bonding

Fig. 4. Model of filled skutterudite structure that emphasizes the pnicogen-pnicogen bonding that results in nearly square pnicogen rings. The transition metal atoms (small white spheres) form a simple cubic lattice as shown. The lines connecting the transition metal atoms have been added for clarity and do not correspond to a chemical bond. The only chemical bonds shown in this model are those that form the pnicogen rings. The lanthanide atoms (large dark spheres) occupy the two voids without a pnicogen ring.

Keywords Structures and binding energies Intennolecular interactions 0—0 and o—ir pnicogen bonds Charge-transfer energies P— p EOM-CCSD spin—spin coupling constants J(P—P)... 

Subsequent to the landmark 2011 paper of Hey-Hawkins et al. [1], there have been many papers published on the subject of intermolecular interactions through the formation of pnicogen bonds [2-32]. This bond arises when a pnicogen atom (N, P, As) acts as a Lewis acid by accepting a pair of electrons from a Lewis base. When two pnicogen atoms participate in forming a bond, each acts as both an electron-pair acceptor and an electron-pair donor. Most studies of pnicogen bonds have involved the PH3 molecule and its derivatives. 

Recently, we asked to what extent a formally sp -hybridized P atom could participate in a P - P pnicogen bond in complexes (H2C=PX>2 and H2C=(X)P PXH2 for a variety of substituents X [30, 32]. In the latter study, we identified a series of complexes stabilized by pnicogen bonds, which involve it electron donation by H2C=PX to PH2X through the ct-hole, and donation of the lone pair of... 

Complexes with pnicogen bonds are stabilized by charge transfer. The more favorable charge-transfer interaction involves donation of the Pt lone pair of PCX to the ct P-A orbital of PH2X. Charge-transfer energies range from... 

Fig. 5 Coupling constants J(P-P) versus the P-P distances for o-n pnicogen bonds in H2XP PCX conformations B red square) and C (green triangle) and H2C=(X)P PXH2 conformation C (blue diamond). The symbol circle includes all complexes for which the best-fit trendline is an exponential...

Ab initio MP2/aug -cc-pVTZ calculations have been carried out on a series of complexes H2XP PCX, for X = F, Cl, OH, NC, CN, CCH, CH3, and H, to identify and characterize ct-ct and ct-tt pnicogen bonds. Three sets of complexes have been identified. 

EOM-CCSD P- p spin-spin coupling constants PJ(P-P) correlate with the P-P distances in conformations A, B, and C. The largest coupling constants are found for conformation A complexes, a result of the nature of the ct-ct pnicogen bond and the dominance of the Fermi contact term. For a given substituent X, the ordering of J(P-P) is A > C > B >. 

Zahn S, Frank R, Hey-Hawkins E, Kirchner B (2011) Pnicogen bonds a new molecular linker Chem Eur J 17 6034-6038... 

Alkorta 1, Sanchez-Sanz G, Elguero J, Del Bene JE (2012) Influence of hydrogen bonds on the P -P pnicogen bond. J Chem Theor Comp 8 2320-2327... 

Alkorta 1, Elguero J, Del Bene JE (2013) Pnicogen bonded complexes of PO2X (X = F, Cl) with nitrogen bases. J Phys Chem A 117 10497-10503... 

Application of calculated indirect spin-spin couplings to investigation of compounds with pnicogen bonds and complexes between electron/proton donors and acceptors... 

Keywords Bond path Bond critical point Laplacian of the electron density Hydrogen bond Halogen bond Pnicogen bond Lewis acid-Lewis base interaction Quantum Theory of Atoms in Molecules (QTAIM) Natural Bond Orbitals (NBO) method o-hole concept Electrostatic potential... 

Eskandari K, Mahmoodabadi N (2013) Pnicogen bonds a theoretical study based on the laplaeian of electron density. J Phys Chem A 117 13018-13024... 

Scheiner S (2013) The pnicogen bond its relation to hydrogen, halogen, and other noncovalent bonds. Acc Chem Res 46(2) 280-288. doi 10.1021/ar3001316... 

Scheiner S (2013) Detailed comparison of the pnicogen bond with chalcogen, halogen, and hydrogen bonds. Int J Quant Chem 113(11) 1609-1620. doi 10.1002/qua.24357... 

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