Synthesis and structures of monomeric [chloro(isatin-3-thiosemicarbazone)bis(triphenylphosphine)]copper(I) and dimeric [dichlorobis(thiophene-2-carbaldehyde thiosemicarbazone)bis(triphenylphosphine)]dicopper(I)] complexes

Reaction of copper(I) chloride with thiophene-2-carbaldehyde thiosemicarbazone (Httsc) in acetonitrile in the presence of Ph3P yielded a sulfur-bridged dimer [Cu2Cl2(μ2-S-Httsc)2(PPh3)2] · 2CH3CN (1), while a similar reaction with isatin-3-thiosemicarbazone (H2itsc) formed a monomer, [CuCl(H2itsc)(Ph3P)2] · 2CH3CN (3). Furan-2-carbaldehyde thiosemicarbazone (Hftsc) also formed a compound of the composition [Cu2Cl2(Hftsc)2(PPh3)2] · 2H2O (2). Complexes 1–3 have been characterized using elemental analysis, IR, 1H and 31P NMR spectroscopy and single crystal X-ray crystallography (1 and 3). Acetonitrile is engaged in hydrogen bonding with the chlorine atom {NCCH2–H⋯Cl)}, which is necessary for the stabilization of the bridging sulfur in 1. In compound 3, however, acetonitrile is strongly hydrogen bonded to the NH hydrogen of the isatin ring {CH3CN⋯NH(isatin)} and not to the chlorine atom. The Cu⋯Cu contact of 2.7719(5) Å in dimer 1 is close to twice the van der Waals radius of the Cu atom (2.80 Å).

Acetonitrile-chlorine hydrogen bonding stabilises sulfur bridging in the reaction of copper(I) chloride with thiophene-2-carbaldehyde thiosemicarbazone (1). Acetonitrile forms a hydrogen bond with the ring of isatin in monomer (3).Figure optionsDownload as PowerPoint slide