Tetrabromoethane as σ-hole donor toward bromide ligands: Halogen bonding between C2H2Br4 and bromide dialkylcyanamide platinum(ii) complexes

Abstract

The complexes trans-[PtBr2(NCNR2)2] (R2 = Me2 1, (CH2)5 2) were cocrystallized with 1,1,2,2-tetrabromoethane (tbe) in CH2Cl2 forming solvates 1 tbe and 2 tbe, respectively. In both solvates, tbe involved halogen bonding, viz. the C-Br Br-Pt interactions, were detected by singlecrystal X-ray diffractions experiments. Appropriate density functional theory calculations (M06/def2- TZVP) performed for isolated molecules and complex-tbe clusters, where the existence of the interactions and their noncovalent nature were confirmed by electrostatic potential surfaces (r = 0.001 a.u.) for isolated molecules, topology analysis of electron density, electron localization function and HOMO-LUMO overlap projections for clusters.