Desulfuration and Cyclization of (Z)-2-[Amino(pyridine-2-yl)methylene]- hydrazonecarbothioamide in the Presence of Manganese(II)

Desulfurization of thiosemicarbazones: the role of metal ions and biological implications

Thiosemicarbazones are biologically active substances whose structural formula is formed by an azomethine, an hydrazine, and a thioamide fragments, to generate a R2C=N-NR-C(=S)-NR2 backbone. These compounds often act as ligands to generate highly stable metal-organic complexes. In certain experimental conditions, however, thiosemicarbazones undergo reactions leading to the cleavage of the chain. Sometimes, the breakage involves desulfurization processes. The present work summarizes the different chemical factors that influence the desulfurization reactions of thiosemicarbazones, such as pH, the presence of oxidant reactants or the establishment of redox processes as those electrochemically induced, the effects of the solvent, the temperature, and the electromagnetic radiation. Many of these reactions require coordination of thiosemicarbazones to metal ions, even those present in the intracellular environment. The nature of the products generated in these reactions, their detection in vivo and in vitro, together with the relevance for the biological activity of these compounds, mainly as antineoplastic agents, is discussed.

The crystal structures of iron and cobalt pyridine (py)-sulfates, [Fe(SO4)(py)4] n and [Co3(SO4)3(py)11] n

The solid-state structures of two metal-pyridine-sulfate compounds, namely catena-poly[[tetra-kis-(pyridine-κN)iron(II)]-μ-sulfato-κ2O:O'], [Fe(SO4)(C5H5N)4] n , (1), and catena-poly[[tetra-kis-(pyridine-κN)cobalt(II)]-μ-sulfato-κ2O:O'-[tetra-kis-(pyridine-κN)cobalt(II)]-μ-sulfato-κ3O,O':O''-[tris-(pyridine-κN)cobalt(II)]-μ-sulfato-κ2O:O'], [Co3(SO4)3(C5H5N)11] n , (2), are reported. The iron compound (1) displays a polymeric structure, with infinite chains of FeII atoms adopting octa-hedral N4O2 coordination environments that involve four pyridine ligands and two bridging sulfate ligands. The cobalt compound (2) displays a polymeric structure, with infinite chains of CoII atoms. Two of the three Co centers have an octa-hedral N4O2 coordination environment that involves four pyridine ligands and two bridging sulfate ligands. The third Co center has an octa-hedral N3O3 coordination environment that involves three pyridine ligands, and two bridging sulfate ligands with one sulfate chelating the cobalt atom.

First-row transition metal-pyridine (py)-sulfate [(py)xM](SO4) complexes (M = Ni, Cu and Zn): crystal field theory in action

The crystal structures of three first-row transition metal-pyridine-sulfate complexes, namely catena-poly[[tetrakis(pyridine-κN)nickel(II)]-μ-sulfato-κ²O:O'], [Ni(SO₄)(C₅H₅N)₄]_n, (1), di-μ-sulfato-κ⁴O:O-bis[tris(pyridine-κN)copper(II)], [Cu₂(SO₄)₂(C₅H₅N)₆], (2), and catena-poly[[tetrakis(pyridine-κN)zinc(II)]-μ-sulfato-κ²O:O'-[bis(pyridine-κN)zinc(II)]-μ-sulfato-κ²O:O'], [Zn₂(SO₄)₂(C₅H₅N)₆]_n, (3), are reported. Ni compound (1) displays a polymeric crystal structure, with infinite chains of Ni^II atoms adopting an octahedral N₄O₂ coordination environment that involves four pyridine ligands and two bridging sulfate ligands. Cu compound (2) features a dimeric molecular structure, with the Cu^II atoms possessing square-pyramidal N₃O₂ coordination environments that contain three pyridine ligands and two bridging sulfate ligands. Zn compound (3) exhibits a polymeric crystal structure of infinite chains, with two alternating zinc coordination environments, i.e. octahedral N₄O₂ coordination involving four pyridine ligands and two bridging sulfate ligands, and tetrahedral N₂O₂ coordination containing two pyridine ligands and two bridging sulfate ligands. The observed coordination environments are consistent with those predicted by crystal field theory.

3-{[5-(4-Chloro-phen-yl)-3-methyl-1H-pyrazol-1-yl]meth-yl}-4-m-tolyl-1H-1,2,4-triazole-5(4H)-thione

In the title compound, C20H18ClN5S, the toluene and triazole rings are oriented almost perpendicular to each other, making a dihedral angle of 89.97 (9)°, whereas the dihedral angle between cholorophenyl and pyrazole rings is 54.57 (11)°. In the crystal, pairs of N-H⋯N hydrogen bonds link the mol-ecules into inversion dimers. Weaker C-H⋯S and C-H⋯Cl inter-actions are also present.