Coinage (Cu, Ag) metal derivatives of salicylaldehyde N-ethylthiosemicarbazone: synthesis, spectroscopy, and structures

Reactions of copper(I) halides with triphenyl phosphine in acetonitrile followed by the addition of salicylaldehyde N-ethylthiosemicarbazone {(2-OH–C6H4)(H)C2=N3–N2H–C1(=S)N1HEt, H2stsc-NEt} in chloroform in 1 : 2 : 1 (Cl) or 1 : 1 : 1 (Br, I) molar ratios yield mononuclear, [CuCl(η 1-S-H2stsc-NHEt)(PPh3)2] (1) and sulfur-bridged dinuclear, [Cu2X2(μ-S-H2stsc-NEt)2(PPh3)2] (X = Br, 4; I, 5) complexes. Similarly, reaction of silver halides (Cl, Br) with H2stsc-NEt in acetonitrile followed by the addition of PPh3 to the solid that formed (1 : 1 : 2 molar ratio), yielding mononuclear complexes, [AgX(η 1-S-H2stsc-NHEt)(PPh3)2] (Cl, 2; Br, 3). All these complexes are characterized with analytical data, IR, and NMR spectroscopy and single-crystal X-ray crystallography. The ligand favored η 1-S bonding in 1, 2, and 3, and μ-S bonding in 4 and 5. Cu ··· Cu contacts were 3.063 A. The complexes form 1-D or 2-D H-bonded networks, entrapping solvent in some cases.