Reaction products distribution between square-planar gold(III) complexes and N,N,N′,N′-tetramethylthiuram disulfide. Crystal structure of bis(N,N-dimethyldithiocarbamato)gold(III) bromide dihydrate, [Au(Me2NCS2)2]Br·2H2O

Summary The reactions of N,N,N,N-tetramethylthiuram disulfide (tmtds) with gold(III) complexes of the [Au(L)X₃] type [L = N-methylimidazole (N-Melm), 2-methylbenzoxazole (2-MeBO) and 2,5-dimethylbenzoxazole (2,5-diMeBO), X = Cl, Br or I] are reported, and yielded two main types of product - [Au(Me₂dtc)X₂] (A) and [Au(Me₂dtc)₂]X (B) (Me₂dtc = N,N-dimethyldithiocarbamato anion). The ratio of the product yields (B/A) depends upon the nature of the ligand (L) and halogen (X). The ratio B/A for the reaction: [Au(L)Cl₃] + tmtds = A + B, increases in the sequence N-MeIm < 2- MeBO < 2,5-diMeBO, which correlates well with the level of cytotoxic activity exhibited by the [Au(L)Cl₃] complexes. A and B were characterized by their i.r., u.v-vis. and ¹-n.m.r. spectra. The magnetic measurements were also recorded. The data support a squareplanar geometry for gold(III) complexes with the Me₂dtc ligand bonded in a bidentate fashion; a conjecture has been verified crystallographically for [Au(Me₂NCS₂)₂]-Br·2H₂O. The X-ray analysis confirmed that the complex is composed of ionic units: [Au(Me₂dtc)₂] ⁺ and Br^– and H₂O molecules. The Au—S distances are markedly similar, falling in the 2.343(4)–2.350(3) A range.     

Influence of the conformers of the ligand 2-methylamino-1-phenylpropan-1-ol (HA) in the complexes (H<Subscript>2</Subscript>A)<Subscript>2</Subscript>[PdCl<Subscript>4</Subscript>] on their state in solutions and their biological activity

The systems Pd(II)-Cl^?-HA-H₂O (where HA are the conformers of 2-methylamino-1-phenylpropan-1-ol) were studied. The acid dissociation constants of the ligands HA and the resulting complexes were determined by pH-metric titration and mathematical modeling. The pH-distribution diagram of the complex species in the system containing different HA conformers was obtained. The complexes (H₂A)₂[PdCl₄] were obtained and structurally characterized; their toxicity and radioprotective effects were estimated. The biological activity of the complexes was found to depend on both the ligand basicity and the hydrogen bonding system formed by different conformers of the ligand in the cation-anion complexes.     

Low-Dimensional Systems and Surface Physics

Transmission electron microscopy is used to study the structure of the surface layer of an Al-7 wt % Si alloy subjected to laser alloying. The base volume is found to be occupied by an aluminum matrix having a braidlike structure. New phases have been revealed, and their composition, shape, and spatial distribution have been determined.     

Mechanism of conductivity in metal-polymer-metal structures

Received: 25 September 1998 / Accepted: 25 November 1998 / Published online: 24 February 1999     

Effect of the Nature of Haloacetic Acids on the Type of Morpholine Complexes Formed. Crystal Structure of the First Palladium Tetracarboxylate with Monocarboxylic Acid: Morpholinium Tetrakis(trifluoroacetato)palladate(II), (O(CH2CH2)2NH2)2[Pd(CF3COO)4]

Russian Journal of Coordination Chemistry - The effect of the nature of halogen-substituted carboxylic acids RCOOH, where R is ClCH2, Cl2CH, Cl3C, or F3C, on the complexation of palladium...     

Palladium(I) Coordination Polymers with Unsaturated Dicarboxylic Acids with Stable Paramagnetic Centers

Russian Journal of Coordination Chemistry - Palladium(I) coordination polymers with unsaturated dicarboxylic acids, {[cis-Pd(C4H2O4)(H2O)]·(H2O)}n (I) (maleic acid),...     

Exploring Peptaibol’s Profile,Antifungal, and Antitumor Activity of Emericellipsin A of Emericellopsis Species from Soda and Saline Soils

Features of the biochemical adaptations of alkaliphilic fungi to exist in extreme environments could promote the production of active antibiotic compounds with the potential to control microorganisms, causing infections associated with health care. Thirty-eight alkaliphilic and alkalitolerant Emericellopsis strains (E. alkalina, E. cf. maritima, E. cf. terricola, Emericellopsis sp.) isolated from different saline soda soils and belonging to marine, terrestrial, and soda soil ecological clades were investigated for emericellipsin A (EmiA) biosynthesis, an antifungal peptaibol previously described for Emericellopsis alkalina. The analysis of the Emericellopsis sp. strains belonging to marine and terrestrial clades from chloride soils revealed another novel form with a mass of 1032.7 Da, defined by MALDI-TOF Ms/Ms spectrometers, as the EmiA lacked a hydroxyl (dEmiA). EmiA displayed strong inhibitory effects on cell proliferation and viability of HCT 116 cells in a dose- and time-dependent manners and induced apoptosis.