Intermolecular hydrogen bonding H···Cl in crystal structure of palladium(II)-bis(diaminocarbene) complex

The reaction of bis(isocyanide)palladium complex cis-[PdCl₂(CNXyl)₂] (Xyl=2,6-Me₂C₆H₃) with excess of 4,5-dichlorobenzene-1,2-amine in a C₂H₄Cl₂/MeOH mixture affords monocationic bis(diaminocarbene) complex cis-[PdClC{(NHXyl)=NHC₆H₂Cl₂ NH₂}{C(NHXyl)=NHC₆H₂Cl₂NH₂}]Cl (3) in moderate yield (42%). Complex 3 exists in the solid phase in the H-bonded dimeric associate of two single charged organometallic cations and two chloride anions according to X-ray diffraction data. The Hirshfeld surface analysis for the X-ray structure of 3 reveals that the crystal packing is determined primarily by intermolecular contacts H–Cl, H–H, and H–C. The intermolecular hydrogen bonds N–H···Cl and C–H···Cl in the H-bonded dimeric associate of 3 were studied by DFT calculations and topological analysis of the electron density distribution within the framework of QTAIM method, and estimated energies of these supramolecular contacts vary from 1.6 to 9.1 kcal/mol. Such non-covalent bonding means that complex 3 is an anionic receptor for the chloride anions.