Syntheses, NMR (1H, 31P) spectroscopy and crystal structures of complexes of copper(I) halides with isatin-3-thiosemicarbazones

Isatin-3-thiosemicarbazones (H(2)itsc) react with copper( I) bromide or iodide in a 1 : 1 mol ratio in acetonitrile in the presence of two moles of Ph3P to form tetrahedral monomeric complexes of composition [CuX(eta(1)-S-H(2)itsc)(Ph3P)(2)], X = Br ( 1), I ( 2). These complexes, which have been characterized by single-crystal structure determinations, are unlike the iodo-bridged dinuclear complex of copper( I) iodide of pyrrole-2-carbaldehydethiosemicarbazone (Hptsc), namely [Cu-2(mu- I)(2)(eta(1)-S-Hptsc)(2)(PPh3)(2)] ( 3). In both 1 and 2, the geometry around Cu is distorted tetrahedral with P - Cu - P bond angles being 121.97( 3) ( 1) and 124.09( 5)degrees ( 2). Proton NMR confirms that thiosemicarbazone coordinates to the Cu atom as a neutral ligand, and P-31 NMR shows that there is no dissociation of the complexes in solution; coordination shift values suggest that Ph3P stabilizes the Cu(I) oxidation state.