H₂C(X)–X···X^–(X = Cl, Br) Halogen Bonding of Dihalomethanes

Abstract

The dihalomethane–halide H 2 C(X)–X···X – (X = Cl, Br) halogen bonding was detected in a series of the cis -[PdX(CNCy){ C (NHCy)═NHC 6 H 2 Me 2 N H 2 }]X•CH 2 X 2 (X = Cl, Br) associates by single-crystal XRD followed by DFT calculations. Although ESP calculations demonstrated that the σ-hole of dichloromethane is the smallest among all halomethane solvents (the maximum electrostatic potential is only 2.6 kcal/mol), the theoretical DFT calculations followed by Bader’s QTAIM analysis (M06/DZP-DKH level of theory) confirmed the H 2 C(X)–X···X – halogen bond in both the solid-state and gas-phase optimized geometries. The estimated bonding energy in H 2 C(X)–X···X – is in the 1.9–2.8 kcal/mol range.