An ab initio study on substituent and cooperative effects in bifurcated fluorine bonds

ABSTRACT

Bifurcated fluorine bond (BFB) interactions are studied in model binary complexes pairing N-formyl formamide derivatives and FX molecules (X = F, CN, NC, CF₃ and CCH) by means of ab initio calculations. The calculated F···O binding distances in these complexes are in the range of 2.813–3.048 Å. The corresponding interaction energies lie in a narrow range, from−2.25 to −16.49 kJ/mol. The nature of BFBs is analysed by a vast number of methods including molecular electrostatic potential, quantum theory of atoms in molecules, non-covalent interaction index and natural bond orbital methods. According to the energy decomposition analysis, the electrostatic and dispersion effects have a dominant role in the formation of these complexes. The formation of a hydrogen- and lithium-bonding interaction tends to increase the strength of BFBs in the ternary XF:NFF-H:NH₃ and XF:NFF-Li:NH₃ complexes, respectively.

KEYWORDS:

• Non-covalent interaction
• electrostatic potential
• halogen bond
• ab initio
• cooperativity

Disclosure statement

No potential conflict of interest was reported by the authors.