Spectral and biocidal studies of palladium(II) and platinum(II) complexes with monobasic bidentate Schiff bases

The monobasic bidentate Schiff base complexes of palladium(II) and platinum(II) derived from 1H-indol-2,3-dione thiosemicarbazone (L¹H) and 1H-indol-2,3-dione semicarbazone (L²H) have been characterized on the basis of elemental analysis, molecular weight determinations, i.r., ¹H n.m.r. and u.v. spectral studies. Based on these studies a square planar environment around the metal atoms has been proposed. Antimicrobial effects of both the ligands and their complexes on different species of pathogenic fungi and bacteria have been recorded and these are found to possess significant fungicidal and bactericidal properties.     

Mg-FeCl3-DMF-H2O: An Inexpensive and Excellent System for Reduction of Aldehydes and Ketones

Aldehydes and ketones are reduced to correspondig alcohols in good yields at room temperature.     

Benzyltriethylammonium Chloride - Zinc- Methanol: A Novel System for Selective Reduction of Aldehydes to Alcohols

A selective reduction of aldehydes to alcohols using benzyltriethy lammoniun chloride - zinc - Methanol System is done.     

Switching behaviour of unijunction transistor in the presence of magnetic field

The influence of magnetic field on some switching parameters (turn-on time, turn-off time and amplitude of the current pulse appearing at base 1 terminal) of a unijunction transistor has been theoretically and experimentally investigated. The various switching parameters are shown to be governed by the magneto-concentration effect.     

Long-range tin-tin coupling constants: II. Two-bond coupling via carbon

Tin-119 and carbon-13 NMR data for a total of 34 compounds containing the grouping Sn-C-Sn (C is either sp³- or sp²-hybridised) are presented and discussed. In organotin derivatives of alkanes, ²J(Sn-C-Sn) can only be correlated with ¹J(Sn-C₂) if a sign change for the former coupling is assumed. In most of the compounds of this type studied, ¹J(Sn-CH₃) is, due to rehybridisation and in contrast to the usual situation, larger than ¹J(Sn-C²); the same is true in some cases for distannylakenes, the behaviour of which is complicated by changes in the torsional angle about the carbon-carbon double bond. Thus correlation of ²J(Sn-C-Sn) with other spectral parameters is not possible in these cases. The total tin chemical shift range for compounds MeⁿSn(CH₂MME₃)_4-n (M  C, Si, Ge, Sn; n  0–4) is 140 ppm. Incorporation of a ditin fragment in a six-membered ring causes a downfield tin shift of 30 ppm.     

Formation of Liesegang rings of mercuric chromate and the effect of gel medium on the condition of mercuric chromate

Summary For the formation of well defined Liesegang rings in different gel media, it is essential to study the effect of gel medium on the condition of the insoluble salt. In case of mercuric chromate, the well defined rings were developed in agar agar and starch gel as the sol formed is coagulable by one of the reactants. In gelatin medium, a very stable sol of mercuric chromate is formed, which is coagulated by hydrochloric acid. Beautiful bands of mercuric chromate were formed in gelatin gel only in presence of hydrochloric acid.

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Zusammenfassung Zur Bildung von gut definierten Liesegang-Ringen in verschiedenen Gel-Medien ist es wesentlich, die Wirkung des Gel-Mediums auf die Bedingung des unl?slichen Salzes zu untersuchen. Im Fall von Quecksilber werden die gut definierten Ringe in Agar-Agar und St?rkegel entwickelt, wenn das gebildete Sol durch einen der beiden Reaktanten koaguliert werden kann. In Gelatine wird ein sehr stabiles Sol von Quecksilber-Chromat gebildet, welches durch Salzs?ure koaguliert wird. Sehr sch?ne Ringe von Quecksilbersulfat bilden sich in Gelatinegel nur in Anwesenheit von Salzs?ure.

     

Microwave-Assisted Synthesis,and Stereochemical and Biological Aspects of Some Antimony(III) and Bismuth(III) Complexes with Biologically Potent Bidentate Schiff Bases

Tetra- and pentacoordinated antimony and bismuth derivatives have been prepared by the interactions of monophenylantimonydichloride(III), trichlorostibane, and trichlorobismuthane with the sodium salts of 3-(indolin-2-one)hydrazinecarbothioamide (L¹H) and 3-(indolin-2-one)hydrazinecarboxamide (L²H), under microwave irradiation as well as by conventional heating. These compounds were further characterized by analytical and spectroscopic techniques including UV, IR, ¹H NMR, and ¹³C NMR spectra. Newly synthesized complexes with their corresponding ligands were also tested for their antifungal and antibacterial activities.     

Synthesis,Spectroscopic Characterization,and In Vitro Antimicrobial Potency of Sulfur-Bonded Complexes of Boron(III)

The present article describes the synthesis and characterization of tetracoordinated boron (III) complexes with monobasic bidentate ligands (L ¹ H, L ² H, L ³ H, L ⁴ H, L ⁵ H, and L ⁶ H) having the general formulae PhB(L)(OH) and PhB(L) ₂ . The 1:1 and 1:2 reactions of phenyl boronic acid with monobasic bidentate ligands resulted in the formation of colored solids. The complexes have been characterized by elemental analysis, molecular weight determinations, and IR and NMR ( ¹ H, ¹³ C and ¹¹ B) spectroscopy, as well as UV-vis spectral studies. Based on these studies, a tetrahedral geometry has been proposed for the resulting complexes. The ligands, along with their complexes, have been screened in vitro against a number of pathogenic fungal and bacterial strains. The studies indicate that the boron chelates are more potent than the parent ligands.     

Microwave synthesis,spectral studies,antimicrobial approach,and coordination behavior of antimony(III) and bismuth(III) compounds with benzothiazoline

The reaction of 2-hydroxy-N-phenylbenzamide with 2-aminobenzenethiol yielded 2-hydroxy-N-phenylbenzamidebenzothiazoline (H₂-Saly · BTZ/HO⋂N⋂SH). The reaction of H₂-Saly · BTZ with PhSbCl₂, SbCl₃, and BiCl₃ under varied reaction conditions (microwave, as well as conventional method) gave corresponding antimony( III) and bismuth(III) Schiff base compounds (substitution along with addition) in different coordination environments. These complexes were characterized by elemental analysis, IR and NMR (¹H and ¹³C) spectral studies. The ligand was found to bifunctional tridentate, as well as monodentate for different starting materials of metal (Sb/Bi), as well as for different reaction conditions, hence, suitable coordination environments and pseudotrigonal bipyramidal geometry for the antimony and bismuth complexes have been proposed. Their biological activities have also been checked against many fungi and bacteria. The complexes were found to be more toxic than the corresponding ligand. The article is published in the original. The article is published in the original.     

Oxidation of some α‐hydroxy acids by tetraethylammonium chlorochromate: A kinetic and mechanistic study

The oxidation of glycolic, lactic, malic, and a few substituted mandelic acids by tetraethylammonium chlorochromate (TEACC) in dimethylsulfoxide leads to the formation of corresponding oxoacids. The reaction is first order each in TEACC and hydroxy acids. Reaction is failed to induce the polymerization of acrylonitrile. The oxidation of α‐deuteriomandelic acid shows the presence of a primary kinetic isotope effect (k_H/k_D = 5.63 at 298 K). The reaction does not exhibit the solvent isotope effect. The reaction is catalyzed by the hydrogen ions. The hydrogen ion dependence has the following form: k_obs = a + b[H⁺]. Oxidation of p‐methylmandelic acid has been studied in 19 different organic solvents. The solvent effect has been analyzed by using Kamlet's and Swain's multiparametric equations. A mechanism involving a hydride ion transfer via a chromate ester is proposed. © 2009 Wiley Periodicals, Inc. Int J Chem Kinet 42: 50–55, 2010