James L. Wardell

Antimony(III) complexes with 2-benzoylpyridine-derived thiosemicarbazones: Cytotoxicity against human leukemia cell lines

The antimony(III) complexes [Sb(2Bz4DH)Cl(2)] (1), [Sb(H2Bz4M)Cl(3)] x 2 H(2)O (2) and [Sb(2Bz4Ph)Cl(2)] (3) were obtained with 2-benzoylpyridine thiosemicarbazone (H2Bz4DH) and its N(4)-methyl (H2Bz4M) and N(4)-phenyl (H2Bz4Ph) derivatives. H2Bz4DH, H2Bz4Ph and complexes (1-3) exhibited high cytotoxic activity against HL-60 and Jurkat human leukemia cell lines. When these compounds were tested against HL-60 cells with ectopic expression of BcrAbl, Bcl-2 or Bcl-X(L), which confer resistance to apoptosis against a variety of death-inducing agents, the cytotoxicity was much lower, indicating apoptosis to be part of their mechanism of action. The cytotoxic activity of complexes 2 and 3 against HL-60 and Jurkat cells was significantly higher than that of the corresponding thiosemicarbazones, suggesting coordination to be an interesting strategy of cytotoxic dose reduction.

Copper(II) complexes with 2-pyridineformamide-derived thiosemicarbazones: spectral studies and toxicity against Artemia salina.

The copper(II) complexes [Cu(H2Am4DH)Cl2] (1), [Cu(H2Am4Me)Cl2] (2), [Cu(H2Am4Et)Cl2] (3) and [Cu(2Am4Ph)Cl] (4) with 2-pyridineformamide thiosemicarbazone (H2Am4DH) and its N(4)-methyl (H2Am4Me), N(4)-ethyl (H2Am4Et) and N(4)-phenyl (H2Am4Ph) derivatives were studied by means of infrared and EPR spectral techniques. The crystal structure of 4 was determined. The studied compounds proved to be toxic to Artemia salina, suggesting that they could present cytotoxic activity against solid tumors. Among the free thiosemicarbazones H2Am4Ph presented higher toxicity than all other compounds, which showed comparable effects. In the case of complexes 2 and 3 toxicity is probably attributable to the complex as an entity or to a synergistic effect involving the thiosemicarbazone and copper. H2Am4Ph and complexes 2 and 3 revealed to be the most promising compounds as potential antineoplasic agents.

An experimental and theoretical study of the electronic spectra of tetraethylammonium [bis(1,3-dithiole-2-thione-4,5-dithiolato)M(III)] and tetraethylammonium [bis(1,3-dithiole-2-one-4,5-dithiolato)M(III)] (M = Sb or Bi)

Metal complexes of dmit and related ligands, such as dmio, have been studied extensively over the last few decades: [dmit](2-) = bis(1,3-dithiole-2-thione-4,5-dithiolato); [dmio](2-) = bis(1,3-dithiole-2-one-4,5-dithiolato). While much effort has been placed on determining structural properties, very few vigorous spectroscopic studies of these metal complexes have been undertaken. The spectroscopic features of the infrared, Raman and UV-vis spectra, previously reported, have largely been used to characterize compounds. In particular, many details of the electronic structure are still to be revealed. We now report a detailed analysis of the UV-vis spectra of the [M(dmit)](-1) and [M(dmio)](-1) anions, where M = Sb(III) or Bi(III). Experimental spectra were deconvoluted and analysed by several theoretical methodologies, including ab initio CI, TD and CISD calculations. The results led to the assignments of several MLCT/LMCT bands, occurring between 390 and 300 nm, and the confirmation of metal orbital contributions to the HOMO-LUMO boundary.

Zinc(II) complexes of 2-pyridine-derived N (4)- p -tolyl thiosemicarbazones: study of in vitro antibacterial activity

Reaction of N(4)-p-tolyl-2-formylpyridine thiosemicarbazone (H2Fo4pT), N(4)-p-tolyl-2-acetylpyridine thiosemicarbazone (H2Ac4pT), and N(4)-p-tolyl-2-benzoylpyridine thiosemicarbazone (H2Bz4pT) with ZnCl2 gave [Zn(H2Fo4pT)Cl2] (1), [Zn(H2Ac4pT)Cl2] (2), and [Zn(H2Bz4pT)Cl2] (3). In the first two complexes a tridentate Npy–N–S thiosemicarbazone binds to the zinc while in the latter N–S coordination occurs. Upon coordination the antibacterial activity against Salmonella typhimurium increases in 1 and 3.

Dibenzo-18-crown-6.

The asymmetric unit of the title compound, C20H24O6, contains two molecules that are identical within standard deviations concerning bond lengths and angles as well as their conformations. In the crystal structure, weak C—H⋯O interactions help to consolidate the packing.

Cyclization of N-alkyldithiocarbamates in alkaline media, a counter example of well-known chemistry – an experimental and theoretical study

In strong alkaline media, the reaction of 2-(tert-butylamino)ethanol (3: R = But) with CS2 at 0°C produced a cyclic dithiocarbamate, 3-tert-butylthiazolidine-2-thione (1: R = But), rather than alkaline metal or ammonium salts of [S2CN(But)CH2CH2OH]−. This is in contrast to isolation of stable alkaline metal or ammonium salts of [S2CN(R)CH2CH2OH]− (R = Me, Et, Pr, or CH2CH2OH) obtained in analogous reactions. The use of Ni(OAc)2, both as a source of Ni(II) and a weaker base, in a one-pot reaction with (3: R = But) and CS2, successfully gave the first reported metal complex of [S2CN(But)CH2CH2OH]−, namely [Ni{S2CN(But)CH2CH2OH}2] (2: R = But). Compounds 1 and 2 have been fully characterized by infrared and NMR spectroscopies, and by X-ray crystallography. DFT calculations on the cyclization and stabilities of [S2CN(R)CH2CH2OH]− (R = Pr and But) have been carried out.

Bis[2-(ethoxy-carbonyl-amino)ethan-aminium] hexa-bromidostannate.

In the title salt, (C5H13N2O2)2[SnBr6], the Sn atom (site symmetry ) exists in a slightly distorted octahedral geometry. The cation is non-planar as the terminal CH2NH3 + residue lies below the plane defined by the remaining non-H atoms. In the crystal, cations associate via N—H⋯O hydrogen bonds involving the ammonium and carbonyl residues, forming a 14-membered {⋯HNC2NCO}2 synthon. The cations and anions are arranged in alternating layers arranged along the a-axis direction, the major association between them being N—H⋯Br contacts.

Bis(2-ethoxy­carbonyl­ethyl-κ2C1,O)(2-thioxo-1,3-dithiole-4,5-dithiol­ato-κ2S4,S5)tin(IV)

In the title compound, [Sn(C5H9O2)2(C3S5)], the immediate environment around the Sn centre is defined by two S and two C atoms that define an approximately tetrahedral geometry. The close approach of the pendant carbonyl O atoms [Sn—O = 2.577 (3) and 2.573 (3) Å] increases the coordination number to six. Supramolecular chains are formed along the a axis in the crystal structure owing to the presence of C—H⋯O contacts.

Dichloridobis(1,10-phenanthroline-5,6-dione-κ2N,N′)mercury(II)

In the title compound, [HgCl2(C12H6N2O2)2], the HgII atom is located on a twofold rotation axis and exists within a distorted octahedral geometry defined by a cis-Cl2N4 donor set. Molecules are connected into layers in the ac plane via extensive C—H⋯Cl contacts as each Cl atom forms two such interactions. Contacts between the layers are of the type C=O⋯π [O⋯centroid distance = 3.110 (8) Å].

Redetermination of phenyl­hydrazinium chloride

In the redetermined structure [Koo (1965 ▶). Bull. Chem. Soc. Jpn, 38, 286] of the title compound, C6H9N2 +·Cl−, the H atoms have been located and the hydrogen-bonding scheme established. A series of N—H⋯Cl and N—H⋯N hydrogen bonds leads to a layered network parallel to the (010) plane.