Stereochemical and biochemical aspects of some organoboron complexes of sulphur donor ligands.

Synthetic, structural and biochemical aspects of some organoboron complexes of sulphur containing ligands having ONS and SNNS donor systems have been described. The ligands were prepared by the condensation of 1-phenyl-1,3-butanedione, 2,4-pentanedione, diphenylethanedione, 2,3-butanedione, ethanedial and 1,4-benzenedialdehyde with 2-mercaptoaniline. The unimolar reactions between phenylboronic acid and these thio-ligands have produced Ph.B (ONS) and Ph.B. (SNNS) type of biologically active complexes. These have been characterized by elemental analysis, molecular weight determinations, and conductivity measurements. Based on UV, IR, 1H NMR, 13C NMR and 11B NMR spectral studies, a tetracoordinated state of boron has been established in all the derivatives. The ligands and their corresponding organoboron complexes have been tested in vitro against a number of pathogenic fungi and bacteria and found to possess remarkable fungicidal and bactericidal properties.

Coordination behavior and antifungicidal, antibacterial, and antifertility activities of dioxomolybdenum(VI) complexes of biologically active heterocyclic benzothiazolines.

Synthesis, characterization, and structural aspects of a new class of dioxomolybdenum(VI) complexes with biologically active benzothiazolines, 2-(2-pyridyl) benzothiazoline, 2-(2-thienyl) benzothiazoline, 2-(2-furyl) benzothiazoline, 2-(3-indolyl) benzothiazoline, glyoxal benzothiazoline, biacetylbenzothiazoline, benzil benzothiazoline, and terphthaldehyde benzothiazoline have been described. The newly synthesized complexes, [MoO2(Bzt)2] and [MoO2(Bzt')] (where BztH and Bzt'H2 represent benzothazoline molecules) have been characterized by elemental analysis, conductance measurements, molecular weight determinations, and magnetic studies. Based on IR, 1H NMR, 13C NMR, and electronic spectral studies, distorted octahedral geometry with cis-MoO2 group has been indicated for the resulting complexes. Two benzothiazolines and their corresponding metal complexes were screened for their antifungicidal and antibacterial activity on several fungi and bacteria and found to be quite active in this respect. In addition, antifertility activity of representative ligands and their molybdenum complexes was also evaluated and discussed in male mice.

Testicular changes in rats after administration of organotin complex.

Intratesticular administration of di-n-butyltin (o-hydroxyacetophenone S-methyldithiocarbazate) has been shown to induce marked degenerative changes in the testes of adult rats. The possible mechanism of its action is discussed. In particular, an atrophy of seminiferous tubules with complete arrest of spermatogenesis has been noted.

Antitumor activity of some diorganotin and tin(IV) complexes of Schiff bases.

Some new di-n-butyltin and tin(IV) complexes of the type Bu2SnL, Bu2SnL2 and SnL2 (where L = anions of Schiff bases derived from S-substituted dithiocarbazates and fluoro-aniline) have been prepared and screened for their antitumor activity in P 388 Lymphocyte Leukaemia system. These complexes do not show any toxicity at low dose levels and display T/C values in the range 94-124. Di-n-butyltin complex derived from salicylaldehyde-S-methyl dithiocarbazate has been found to be the most active in this series.

Formation constants of ternary complexes of vanadium(IV) with picolinic acid and salicylic or 5-sulphosalicylic acid.

The formation constants, beta(MAL), for the reaction VO(2+) + A(-) + L(2-) <==> VOAL(-) [where HA = picolinic acid and H(2)L = salicylic or 5-sulphosalicylic acid] have been determined at 30 +/- 1 degrees (mu = 0.1, KNO(3)). Potentiometric evidence is presented for the simultaneous addition of both ligands to the metal ion to form the 1:1:1 ternary complex.

Potentiometric studies of ternary complex formation Cu(II), Ni, Zn or Cd iminodiacetic acid/amino-acid complexes.

The formation constants, log K(mab), for the reactions MA + B right harpoon over left harpoon MAB [where M = Cu(II), Ni, Zn or Cd, A = terdentate ligand and B = bidentate or terdentate ligand] have been determined. Potentiometric evidence is presented for the stepwise addition of the secondary ligand B to the 1:1 metal iminodiacetate (MA). The formation constants and the free energies of formation (DeltaG) have been calculated at 25 +/- 1 degrees and mu = 0.10. The order in terms of secondary ligands has been found to be ASPA > Gly > Aln and Gly > Aln > ASPA with iminodiacetic and nitrilotriacetic acid as primary ligands respectively (ASPA = aspartic acid, Gly = glycine, Aln = dl-alanine). The plot of log K(mab) against log k(mb)(2) shows a linear relationship between the formation constants of the ternary and 1:2 M(II)secondary ligand complexes.

Potentiometric studies of the complexes of chromium(VI), molybdenum(VI) and tungsten(VI) with some Azoxine S dyes.

The equilibrium constants of the complexation reactions of Cr(VI), Mo(VI) and W(VI) with 8-hydroxyquinoline-5-sulphonic acid (OXS), 7-phenylazo-8-hydroxyquinoline-5-sulphonic acid (PAZOXS), 7-(4-sulphophenylazo)-8-hydroxyquinoline-5-sulphonic acid (SPAZOXS) and 7-(4-sulphonaphthylazo)-8-hydroxyquinoline-5-sulphonic acid (SNAZOXS) have been determined by potentiometric pH titration. The values in the case of chromate are different from those for molybdate and tungstate. The order of stabilities is OXS > PAZOXS > SPAZOXS > SNAZOXS.

Spectrophotometric determination of zirconium with 2-(1-hydroxy-4,6-dinitro-2-phenylazo)-1,8-dihydroxynaphthalene-3,6-disulphonate (picramine ca) as chromogenic reagent.

The title compound has been used as a selective reagent for the micro-determination of zirconium in acidic medium (0.5MHCl) and found to be better than Picramine R. Spectrophotometric studies show the formation of a 2:1 (ligand:Zr) water-soluble complex and the reaction is suitable for photometric determination of 0.4-2.8 ppm of zirconium. The colour takes about 90 min to develop fully and is stable for about 20 hr. The molar absorptivity of the complex is 2.4 x 10(4) and the equilibrium constant is of the order of 10(10). The interference due to a number of ions has been studied.

Studies on vanadium(IV) complexes of azoxine s dyes.

Comparative studies of the reaction of 7-arylazo-8-hydroxyquinoline-5-sulphonic acid (Azoxine S) dyes with vanadium(IV), show that 2:1 yellow, water-soluble complexes are formed over the pH range 2.5-6, and that the phenyl derivative is the most suitable for spectrophotometric determination of 0.2-1.4 ppm of vanadium(IV). The colour is formed instantaneously and is stable for about 8 hr. The molar absorptivity at lambda(max), 400 mmu;, is 1.15 x 10(4), and the equilibrium constant for complex formation is of the order of 10(2). These dyes can also be used as indicators in the direct complexometric determination of vanadium(IV). The interference of a number of anions and cations is reported.

Vanadium compounds in reductimetric titrations-III: Applications of vanadium(II).

Vanadium(II) sulphate is a versatile reductant; it can change its oxidation number by one, two, or three units, depending on the oxidation potential of the half-cell with which it reacts and on the mode of titration. The end-point of many of the reactions can be detected by means of indicators. A back-titration method is usually needed for the three-electron oxidation of vanadium(II).

Vanadium compounds in reductimetric titrations-II Standardisation of vanadium(II) sulphate with common oxidising agents and determination of binary mixtures.

Methods for the standardisation of vanadium(II) sulphate are described. With weak oxidising agents, e.g., Fe(III)/Fe(II) in phosphoric acid, vanadium(II) undergoes a one-electron change, which is satisfactorily indicated by Neutral Red, Phenosafranine or Safranine T, or by potentiometry. Stronger oxidising agents oxidise vanadium(II) to vanadium(IV); Variamine Blue, Methylene Blue, o-dianisidine, cacotheline, ferroin, bis(alpha,alpha'-bipyridyl)iron(II) and ammonium molybdate are satisfactory indicators. Binary mixtures of oxidising agents can be determined.