Fluorines in tetrafluoromethane as halogen bond donors: Revisiting address the nature of the fluorine'sσ_hole

Abstract

It has been demonstrated in several instances that the 0.001 a.u. (electrons per bohr3) isodensity mapped electrostatic surface potentials on the fluorines along the outermost extensions of the CF covalent bonds in tetrafluoromethane (CF4) are entirely negative, they are thereby unable to engage in σhole bonding interactions with the negative sites on another molecules. In this study, we have attempted at resolving this controversy by performing various high‐level electronic structure calculations with Quadratic Configuration Integrals of Singles and Doubles QCISD(full), second‐order Møller–Plesset MP2(full), and 12 other Density Functional Theory (DFT) based functionals with and without dispersion corrections, all in conjunction with the 6–311++G(2d,2p) basis set. The results achieved with all the levels of theory utilized suggest that the fluorine's σholes in CF4 are positive regardless of the 0.001‐, 0.0015‐, and 0.002‐a.u. isodensity mapped electrostatic surfaces examined. Because of this specific quality, the fluorines in CF4 have displayed their capacities to form not only 1:1 clusters with the Lewis bases such as water (H2O), ammonia (NH3), formaldehyde (H2CO), hydrogen fluoride (HF), and hydrogen cyanide (HCN), but also 1:2, 1:3, and 1:4 clusters with the latter three randomly chosen Lewis bases. Various topological and nontopological features obtained from applications of atoms in molecules, noncovalent interaction reduced‐density‐gradient and natural bond orbital analytical tools reveal that the N···F, O···F, and F···F long‐ranged interactions developed between the interacting monomers in H3N···FCF3, H2O···FCF3, and (YD)n=1–4···F4C (YD = H2CO, HCN, and HF) are reminiscent of halogen bonding. The nonadditive cooperative and anticooperative energetic effects emerged on cluster formations are discussed in detail. © 2015 Wiley Periodicals, Inc.

Competition between hydrogen and halogen bonding in halogenated 1‐methyluracil: Water systems

“…Since the pioneering work by Brinck et al, many studies have used molecular electrostatic potential maps to demonstrate the σ‐hole in possible halogen‐bond donors, see for example references . Figure shows the electrostatic potential surfaces of the halogenated methyluracil molecules studied in this work.…”

“…This has been attributed to the high electronegativity of fluorine and its tendency to engage in significant sp hybridization, which produces an influx of negative charge into the region where the positive σ‐hole would be . Some recent studies state that organic fluorines can form halogen bonds when strongly electronegative substituents are bound to the carbon . However, it has been suggested that this type of bond should not be labelled a halogen bond, as there are fundamental differences between these interactions and halogen bonds involving Cl, Br, and I .…”

Do surfaces of positive electrostatic potential on different halogen derivatives in molecules attract? like attracting like!

“…The first, a halogen bond, which is formed when a positive region on the halogen in a molecule attracts a negative site (as in H 3 N•••F 2 , for example). The second, a σ‐hole, which is a region of deficiency of electron density on the electrostatic surface of the atom Y along the outer extension of the RY σ‐bond in molecules, which can be positive, negative, or neutral . The atom Y can be a halogen derivative X (X = Cl, Br, I), or any other main group element of the periodic table (mainly atoms of groups 14–17).…”

“…Thus, an atom possessing a positive σ‐hole in a molecule can attract the negative site on another molecule to form an intermolecular noncovalent interaction. Such an attractive interaction has been referred to as either halogen bonding, or σ‐hole centered bonding …”

On the correction of calculated vibrational frequencies for the effects of the counterions — α,ω-diamine dihydrochlorides

“…Despite these prior findings, the efficiency of the mPW1PW/6-31G * level was once more evaluated, within this new context, by comparison with the results obtained using a higher theory level that combines a long-range corrected hybrid functional, ωB97XD, with a much larger basis set, 6-311++G(2d,2p). The choice of this theory level was based on its well documented high performance regarding the description of hydrogen bonding [39][40][41][42].…”