A Combined Theoretical and Cambridge Structural Database Study of π-Hole Pnicogen Bonding Complexes between Electron Rich Molecules and Both Nitro Compounds and Inorganic Bromides (YO₂Br, Y = N, P, and As)

Abstract

Quantum calculations at the DFT-D3/def2-TZVPD level of theory have been used to examine complexes between O2YBr (Y═N, P, and As) molecules and several Lewis bases, that is, NH3, H2O, and HF. The interactions of the lone pair of the ammonia, water, and hydrogen fluoride with the σ-hole and π-hole of O2YBr molecules have been considered. In general, the complexes where the Lewis base lone pair interacts with the π-hole are more favorable than those with σ-hole. The nature of the interactions has been characterized with the Bader theory of atoms in molecules (AIM). We have also studied the ability of trifluoronitromethane and nitromethane to interact with anions using their π-hole along with an analysis the Cambridge Structural Database. We have found a large number of hits that provide strong experimental support for ability of the nitryl (-NO2) group to interact with anions and Lewis bases. In some X-ray structures, the π-hole interaction is crucial in the crystal packing and has a strong influence in the solid state architecture of the complexes. Finally, due to the relevance in atmospheric chemistry, we have studied noncovalent σ/π-hole complexes of nitryl bromide with ozone.

Electrochemical Azidooxygenation of Alkenes Mediated by a TEMPO–N3 Charge-Transfer Complex

“…I 4 appeared most energetically favorable among all plausible structures examined. Structural and energetic agreement across a series of DFT methods (see table in Figure 6), including methods consistent with previous studies of metal-free charge-transfer complexes, 33 offers strong evidence for the validity of these models.…”

Non-additivity between substitution and cooperative effects in enhancing hydrogen bonds

“…64 This is consistent with the conclusion that the complexes (between O 2 YBr (Y= N, P, and As) molecules and three Lewis bases NH 3 , H 2 O, and HF) where the Lewis base lone pair interacts with the π-hole are more favorable than those with the σ-hole. 65 ZB in 7 is stronger than that in 5, consistent with the negative MEP on the C end of CNH (−0.0529 au) and N one of NCH (−0.0509 au). This result can also be explained with the average local ionization energies on the molecular surfaces of both molecules, which are 66 The smaller average local ionization energy indicates that the carbon in CNH has more reactive electrons than the nitrogen in NCH.…”

Theory Meets Experiment for Noncovalent Complexes: The Puzzling Case of Pnicogen Interactions

“…The conformational landscape exploration and stationary points characterization have been performed using state-of-the-art quantum-chemical computations providing significant insights on structure determination. Among others,worth of mention are those studies that led to the characterization of heavy pnicogen···p interactions [9] and of the P···P, [10] P···N, [11,12] and P···O noncovalent bonds. Along with the well-established hydrogen and halogen bonds,e merging classes of noncovalent interactions are attracting increasing attention, such as the R À X···Y ones involving apnicogen atom (X = N, P, As,SborBi), [6] with RÀXand Ybeing the pnicogen bond donor and acceptor,r espectively,i na nalogy with hydrogen [7] and halogen bond definitions.…”

“…Noncovalent interactions play ak ey role in several biological [1] and technological processes, [2][3][4][5] yet their characterization and interpretation are still far from being satisfactory,especially when the bonding pair is made up of two nonhydrogen atoms.I nt his connection, integrated experimental and computational investigations can play an invaluable role provided that the accuracy of the results is accompanied by their rigorous and understandable interpretation. [12] In particular,i th as been recently suggested that the last two interactions might play ar ole in catalytic mechanisms involving phosphorous compounds. [8] Several spectroscopic investigations,r anging from NMR to X-ray,a nd theoretical calculations have been devoted to the description of this kind of noncovalent interactions.…”