Synthesis, crystal structure and DFT study of a dinuclear CuI complex with (E)-2-benzylidene- N-methylhydrazinecarbothioamide: Role of halogen-hydrogen bonds in copper-copper bridge bonding

Abstract

An equimolar reaction of copper(I) chloride with the (E)-2-benzylidene-N-methylhydrazinecarbothioamide (btscH-N1HMe) thio-ligand in acetonitrile followed by the addition of one equivalent of triphenylphosphine (Ph3P) gave crystals. The elemental analysis, and infrared and proton NMR spectra of the crystals supported the empirical composition, {CuCl(Ph3P)(btscH-N1HMe)}, and single crystal X-ray crystallography revealed formation of the dinuclear compound, [Cu2(µ-Cl)2(Ph3P)2(κ1S-btscH-N1HMe)2] (1). There is intramolecular H-bonding between the hydrazinic hydrogen atom (N2-H) and chloride ion {NH⋅⋅⋅Cl, 2.29; N⋅⋅⋅Cl, 3.144 Å}. The intermolecular H-bonding between the dimeric units led to the formation of a H-bonded 1 D polymer. DFT calculations on complexes of copper(I) halides with the model thiosemicarbazone, {H2C2=N3-N(H)-C(=S)-N1HMe}, and PH3 as a co-ligand, revealed the formation of halogen-bridged or sulfur-bridged dinuclear complexes, without or with the halogen - solvent/water hydrogen bonding. Some interesting conclusions are inferred from the experimental-theoretical correlations.