Chemistry of Heterocyclic 2-Thiones: In Situ Generation of 3-(2-Thiazolin-2-yl)thiazolidine-2-thione and 1,1′-Dimethyl-2,2′-diimidazolyl Sulfide and Their Coordination to CuI and CuII



The chemical reactivity of copper(I) chloride/copper(I) bromide, [CuI(NCCH3)4](BF4), and copper(II) nitrate towards a series of heterocyclic-2-thiones under aerobic conditions is described. Thiazolidine-2-thione (NC3H5S2) in CH3CN in the presence of copper(I) chloride/bromide and [CuI(NCCH3)4](BF4) was transformed into 3-(2-thiazolin-2-yl)thiazolidine-2-thione (C3H4S2N-C3H4SN) through C–S bond cleavage and the formation of a C–N bond between two heterocyclic rings. This new thio ligand (C3H4S2N-C3H4SN) chelates to CuI through N,S-donor atoms, and the third site is occupied by the halogen atoms (Cl, Br), which leads to the formation of three-coordinate CuI complexes, [CuIX(κ2-N,S-C3H4S2N-C3H4SN)] [X = Cl (1), Br (2)], and a four-coordinate N,S-chelated complex, [CuI2-N,S-C3H4S2N-C3H4SN)2](BF4) (3), is obtained in the presence of BF4. In each case, the formation of CuSO4·5H2O was also observed. Upon reaction of 1-methylimidazoline-2-thione (N2C4H6S) with [CuI(NCCH3)4](BF4) or copper(II) nitrate in CH3CN or CH3CN/MeOH, respectively, the thio ligand is converted into 1,1′-dimethyl-2,2′-diimidazolyl sulfide (N2C4H5)2S (a thioether), which prefers to bind to CuII (in situ formed) to yield six-coordinate N,N-chelated octahedral complexes, namely, {CuII2-N,N-(N2C4H5)2S]21-OH2)2}X2 [X = BF4 (6), NO3 (7)], with water in the axial positions. The transformation of the thio ligand into 1,1′-dimethyl-2,2′-diimidazolyl sulfide is also observed in its copper(I) chloride reaction in acetonitrile, which yields an N,N-chelated chloro-bridged dimer, {CuII22-N,N-(N2C4H5)2S]2(μ-Cl)2Cl2} (5). Reaction of copper(I) iodide with thiazolidine-2-thione and 1-methylimidazolidine-2-thione (N2C4H8S) in acetonitrile yields an iodo-bridged dimer, [Cu21-S-NC3H5S2)4(μ-I)2] (4), and a novel polymer, [Cu43-I)2(μ-I)2(μ-S-N2C4H8S)21-S-N2C4H8S)]n (8), respectively.