Ab Initio Investigation of the Complexes between Bromobenzene and Several Electron Donors:  Some Insights into the Magnitude and Nature of Halogen Bonding Interactions

Abstract

Halogen bonding, a specific intermolecular noncovalent interaction, plays crucial roles in fields as diverse as molecular recognition, crystal engineering, and biological systems. This paper presents an ab initio investigation of a series of dimeric complexes formed between bromobenzene and several electron donors. Such small model systems are selected to mimic halogen bonding interactions found within crystal structures as well as within biological molecules. In all cases, the intermolecular distances are shown to be equal to or below sums of van der Waals radii of the atoms involved. Halogen bonding energies, calculated at the MP2/aug-cc-pVDZ level, span over a wide range, from -1.52 to -15.53 kcal/mol. The interactions become comparable to, or even prevail over, classical hydrogen bonding. For charge-assisted halogen bonds, calculations have shown that the strength decreases in the order OH- > F- > HCO2- > Cl- > Br-, while for neutral systems, their relative strengths attenuate in the order H2CS > H2CO > NH3 > H2S > H2O. These results agree with those of the quantum theory of atoms in molecules (QTAIM) since bond critical points (BCPs) are identified for these halogen bonds. The QTAIM analysis also suggests that strong halogen bonds are more covalent in nature, while weak ones are mostly electrostatic interactions. The electron densities at the BCPs are recommended as a good measure of the halogen bond strength. Finally, natural bond orbital (NBO) analysis has been applied to gain more insights into the origin of halogen bonding interactions.

The Diiodine Basicity Scale: Toward a General Halogen‐Bond Basicity Scale

“…[23,25,27,29,[33][34][35][36][37][38][39] Halogen bonding has recently been recognised as a significant interaction in molecular recognition and self-assembly processes, [40,41] and is therefore employed for a wide range of applications in materials, [42][43][44][45] synthetic [46][47][48] and medicinal chemistry. [49][50][51][52] Concerning the fundamentals of halogen bonding, recent studies have focused mainly on structural determinations [18][19][20][21][22] and on quantum mechanical calculations of the bond energy in vacuo at 0 K. [25][26][27][28][29][30][31][53][54][55][56][57][58][59][60] The experimental knowledge of the thermodynamics of the halogen bond at room temperature in solution shows a marked contrast between inorganic and organic halogen-bond donors. In addition to the thousand complexation constants for diiodine, [1] about ...…”

CX⋅⋅⋅O Halogen Bonding: Interactions of Trifluoromethyl Halides with Dimethyl Ether

“…These interactions, often referred to as halogen bonding, [1,2] not only involve dihalogens of the types X 2 and XY, [3][4][5][6][7] but also appear for a variety of carbon-bound halogen atoms occurring in alkyl and aryl halides. [3][4][5][6] These non-covalent interactions between the carbon-bound halogen atoms and electron donors have been proven to be an essential driving force for crystal engineering and supramolecular self-assembly, [7][8][9][10][11][12][13][14] molecular recognition, [15][16][17][18] and various biochemical processes, [19][20][21][22] and, consequently, have been the subject of a variety of experimental and theoretical studies. [23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39] Experimental studies involving CÀhalogen···Y interactions tend to concentrate on Lewis bases Y in which the electron donor atom is nitrogen.…”

Magnitude and Origin of the Attraction and Directionality of the Halogen Bonds of the Complexes of C6F5X and C6H5X (X=I, Br, Cl and F) with Pyridine

“…MP2 calculations of the halogen bond of bromobenzene have recently been reported. [71] Ab initio calculations of the complexes of aromatic molecules have shown that a very large basis set near saturation and CCSD(T) level electron correlation is necessary for a quantitative evaluation of the intermolecular interaction energies of aromatic molecules. [87][88][89][90] Unfortunately, however, calculations on the halogen bond of aryl halide molecules at the CCSD(T) level have not been reported.…”

“…[68,72,73] On the other hand, it has been stressed repeatedly that charge-transfer (orbital-orbital) interactions are an important source of the attraction in halogen bonds. [7,[69][70][71][72][73][74][75][76][77][78][79] The strong correlation between the electron-density transfer and the interaction energy suggests that charge-transfer interactions play important roles in the attraction. The chargetransfer contribution can explain the directionality of the halogen bond.…”