Metal-Involving Bifurcated Halogen Bonding C-Br⋯η 2 (Cl-Pt)

Abstract

The complexes trans-[PtCl 2 (NCNR 2 ) 2 ] (R 2 = Me 2 1, Et 2 2, (CH 2 ) 4 3) were cocrystallized with CBr 4 in CHCl 3 (1 and 3) or in MeNO 2 (2) forming adducts 1·CHCl 3 ·CBr 4 , 2·2CBr 4 , and 3·2CBr 4 , respectively. In two out of three adducts, viz. 1·CHCl 3 ·CBr 4 and 2·2CBr 4 , unique Br 3 C-Br⋯ η 2 (Cl-Pt) metal-involving bifurcated halogen bonding was detected, by single-crystal XRD, along with other halomethane-chloride interactions. Appropriate density functional theory calculations performed by two complementary methodologies, (i) single-point "quasi-solid state" calculations with topological analysis of the electron density distribution within the framework of Bader theory (QTAIM method) and (ii) Kohn-Sham calculations with periodic boundary conditions, confirmed the existence of the bifurcated interactions and their noncovalent nature. Estimated energies of these interactions vary from 1.1 to 4.7 kcal/mol.