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

Abstract
Isatin-3-thiosemicarbazones (H2itsc) 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(η1-S-H2itsc)(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 [Cu2(μ-I)21-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)° (2). Proton NMR confirms that thiosemicarbazone coordinates to the Cu atom as a neutral ligand, and 31P NMR shows that there is no dissociation of the complexes in solution; coordination shift values suggest that Ph3P stabilizes the Cu(I) oxidation state.

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