Synthesis, spectroscopy and structures of halogen and sulfur-bridged dinuclear silver(I) complexes with N 1-substituted thiophene-2-carbaldehyde thiosemicarbazone

Abstract

The reactions of silver(I) halides (Cl or Br) with thiophene-2-carbaldehyde N 1-methyl thiosemicarbazone (HttscMe) in the presence of Ph 3P (1:1:1 molar ratio) yield halogen-bridged dimers, [Ag 2(μ-X) 2(η 1-S-HttsMe) 2(PPh 3) 2] (X = Cl, 1; Br, 2). The use of 2,2′-bipyridine in lieu of Ph 3P in the reaction of silver(I) chloride with HttscMe yields the sulfur-bridged dimer, [Ag 2(μ-S-HttscMe) 2(η 1-HttsMe) 2] · 2CHCl 3 3. The substituents have altered the nature of bridge between the two silver atoms. The Ag···Ag separation (3.4867(5) Å) in complex 3 is less than that in the halogen-bridged dimers (3.734(4) Å 1; 3.746(5) Å 2). Unlike PPh 3 the co-ligand 2,2′-bipyridine did not coordinate to the silver center, but was necessary for crystallization in the reaction with the thio-ligand. NMR spectroscopy revealed that the complexes remained unchanged in the solution state (CDCl 3).