H2C(X)-X···X- (X = Cl, Br) Halogen Bonding of Dihalomethanes.

The dihalomethane-halide H2C(X)-X···X- (X = Cl, Br) halogen bonding was detected in a series of the cis-[PdX(CNCy){<underline>C</underline>(NHCy) NHC6H2Me2<underline>N</underline>H2}]X•CH2X2 (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 H2C(X)-X···X- halogen bond in both the solid-state and gas-phase optimized geometries. The estimated bonding energy in H2C(X)-X···X- is in the 1.9-2.8 kcal/mol range. [ABSTRACT FROM AUTHOR]