Synthesis, structure and spectroscopy of mono- and di-nuclear copper(I) complexes incorporating anionic thiophene based thiosemicarbazones-first examples

This paper reports six copper(I) complexes with a series of thiophene based N1-substituted thiosemicarbazones, {(C4H3S)R1C2N3–N2(H)–C1(S)N1HR2} (R1 = H, R2 = Me, Et, Ph, abbrev. HttscN–R2; R1 = CH3; R2 = Et, Ph, abbrev. HattscN–R2) by reacting these thio-liands with [Cu(OAc)(PPh3)2. Here the acetate deprotonated –N2–H hydrogen and the anionic thio-ligands have yielded mono- and di-nuclear complexes (1–6). For R1 = H at C2 carbon, the N3, S-chelated complexes, [Cu(κ1N3, κ1S–ttscN–R2)(PPh3)2] (R2 = Me 1; Et, 2; Ph 3) were formed in methanol. For R1 = Me, the N3, S-chelated-cum-sulfur bridged (κ1N3, κ2S) dinuclear complexes, namely, [Cu2(κ1N3,κ2S–attscN–R2)2(PPh3)2] (R2 = Et 5, Ph 6) were obtained in CH2Cl2–CH3OH. In one case for R1 = H and with R2 = Me, a dinuclear complex, [Cu2(κ1N3,κ2S–ttscN–Me)2(PPh3)2] 4 similar to 5/6 has been isolated in CH2Cl2–CH3OH. The Cu2S2 cores of dimers form parallelograms with the Cu⋯Cu distances in the range, 2.668–2.774 Å which are less than twice the sum of van der Waals radius of Cu, 2.80 Å. Complexes 1–6 represent first examples in the domain of thiophene based anionic thiosemicarbazones in which the thio-ligands satisfy the primary valency and bind in N,S-chelation mode (1–3) or N,S-chelation-cum-S-bridging mode (4–6).

Six new copper(I) complexes with thiophene based anionic thiosemicarbazones are reported: three mononuclear (1–3) with N3,S-chelation and three dinuclear (4–6) with N3,S-chelation-S-bridging. It was found that for R1 = H and R2 = Me, the thio-ligand HttscN–Me yielded a mononuclear complex 1 in methanol solvent and a dinuclear complex 4 in methanol–dichloromethane mixture. For R1 = Me, there is preference for the formation of dinuclear complexes (5, 6).Figure optionsDownload as PowerPoint slide