Abstract
An extensive series of 128 halogen-bonded complexes formed by trimethylphosphine oxide and various F-, Cl-, Br-, I- and At-containing molecules, ranging in energy from 0 to 124 kJ/mol, is studied by DFT calculations in vacuum. The results reveal correlations between R–X⋅⋅⋅O=PMe3 halogen bond energy ΔE, X⋅⋅⋅O distance r, halogen’s σ-hole size, QTAIM parameters at halogen bond critical point and changes of spectroscopic parameters of phosphine oxide upon complexation, such as 31P NMR chemical shift, ΔδP, and P=O stretching frequency, Δν. Some of the correlations are halogen-specific, i.e., different for F, Cl, Br, I and At, such as ΔE(r), while others are general, i.e., fulfilled for the whole set of complexes at once, such as ΔE(ΔδP). The proposed correlations could be used to estimate the halogen bond properties in disordered media (liquids, solutions, polymers, glasses) from the corresponding NMR and IR spectra.
Highlights
Halogen bonding is one of the most abundant non-covalent interactions in chemistry [1,2]
We have considered a large set of 128 halogen-bonded complexes formed by trimethylphosphine oxide and halogen donors belonging to various classes of chemical compounds
The Me3 P=O molecule could be considered as a probe used to characterize the halogen-donating ability of isolated F, Cl, Br, I- and At-containing species
Summary
Halogen bonding is one of the most abundant non-covalent interactions in chemistry [1,2]. Due to the anisotropic distribution of electron density around the covalently bound halogen atom, it has two distinct regions: (a) the region of increased electron density (nucleophilic site), located perpendicular to the covalent bond and corresponding to negative values of electrostatic potential (ESP) and (b) the region of decreased electron density (electrophilic site), called σ-hole [3], located along the covalent bond. It is the existence of the electron-depleted σ-hole that determines the ability of the halogen atom to participate in attractive interactions with electron-donating atoms or groups [4,5,6], forming the so-called halogen bond R–X···Y (X—halogen atom). The range of halogen bond interaction energies is similar to that for hydrogen bonds, spanning from a fraction of kJ/mol up to 150 kJ/mol [7,8]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
