Molecular Conductance Measurements Research Articles

Biochemical aspects and structural characterization of sulphur bonded oxovanadium(V) and manganese(II) complexes

The preparation, characterisation and biological activities of some oxovanadium(V) and manganese(II) complexes of ligands having nitrogen-sulphur donor sets are described. Reaction of VOCl3 and MnCl2 with HTSCZ (HTSCZ = thiosemicarbazone) resulted in the formation of complexes of the type [VOCl2(TSCZ)], [MnCl(TSCZ)H2O], [VOCl(TSCZ)2] and [Mn(TSCZ)2]. These have been characterized by elemental analyses, molecular weight determinations and conductivity measurements and found to be monomeric and nonelectrolytes. Distorted trigonal bipyramidal (1∶1) and octahedral (1∶2) geometries for the vanadium(V) complexes and a tetrahedral geometry for the manganese(II) complexes are proposed. All the free ligands and their complexes have been tested in vitro against a number of pathogenic fungi and bacteria and were found to possess good fungicidal and bactericidal properties.

SYNTHESIS, CHARACTERIZATION AND BIOCIDAL EFFECTS OF TRIORGANOLEAD(IV) COMPLEXES DERIVED FROM THIO-LIGANDS

Abstract The substitution reactions of heterocyclic thiosemicarbazones with triphenyllead(IV) chloride in 1:1 molar ratio give Ph3PbL (L = anion of thiosemicarbazone derived from heterocyclic aldehyde or ketone) type of complexes. The elemental analyses, molecular weight determinations, conductivity measurements and spectral (IR, 1H and 13C NMR) studies have been used to elucidate their penta-coordinated structures. Some representative ligands and their metal chelates have also been screened for their antimicrobial effects against different species of pathogenic fungi and bacteria.

Preparative and Spectroscopic Studies of Triorganostanno Derivatives of Bio-Active Heterocyclic Azomethines

Abstract Reactions of triphenyltinchloride and azomethine ligands having the donor groups and have resulted in complexes of the types and , respectively. The newly synthesized complexes have been characterized as monomeric non-electrolytes on the basis of molecular weight determinations and conductivity measurements. Infrared and multinuclear NMR spectral studies (H1, 13C and 119Sn) of some complexes are consistant with the five-coordinated trigonal bipyramidal geometry for the resulting derivatives. Fungitoxicity tests for a few representative ligands and their metal chelates against Alternaria brassicae, Alternaria tenuis and Aspergillus niger have been carried out and the growth inhibition percentage calculated on the basis of average diameter of the fungal colony.

BIOCHEMICAL STUDIES ON BIOLOGICALLY ACTIVE THIO-LIGANDS BENZOTHIAZOLINES AND THEIR MANGANESE(II) COMPLEXES

Abstract The coordination behaviour of benzothiazolines having the donor group N⌢S towards manganese(II) has been studied. The unimolar and bimolar reactions of hydrated manganese acetate with monobasic bidentate benzothiazolines resulted in the formation of coloured solids which have been characterised by elemental analysis, molecular weight determinations conductance and magnetic measurements. The infrared, electronic and electron spin resonance spectral studies indicate a high spin tetrahedral geometry for the resulting complexes. All the ligands and their corresponding complexes have been screened for their fungicidal and bactericidal activity.

SYNTHETIC, STEREOCHEMICAL AND BIOLOGICAL ASPECTS OF ORGANOANTIMONY(III) DERIVATIVES OF THIO-IMINES

Abstract Diphenylantimony(III) derivatives of monobasic bidentate thiosemicarbazones derived from heterocyclic aldehydes and ketones have been synthesized and characterized by elemental analyses, molecular weight determinations and conductance measurements. The stereochemical features of these newly synthesized complexes have been discussed in terms of IR, 1H NMR and 13C NMR spectral data. Some representative ligands and their metal chelates have also been screened for their antifungal activity.

Organosilicon(IV) Complexes of Deprotonated Form of Semicarbazones

Abstract The synthesis and structural features of some trimethyl- and triphenylsilicon(IV) complexes with monofuctional bidentate semicarbazones derived by the condensation of 2-acetylfuran, 2-acetylthiophene, 2-acetylpyridine or 2-acetylnaphthalene with semicarbazide hydrochloride are described. The products Me3Si(L) and Ph3Si(L) were obtained by the 1:1 stoichiometric interactions of trimethylchlorosilane and triphenylchlorosilane with sodium salts of oxygen donor ligands, (HL), in anhydrous methanol. The penta-coordinated environment around silicon(IV) is proposed on the basis of IR, 1H NMR and 13C NMR spectral studies, molecular weight determinations and conductance measurements.

SPECTRAL CHARACTERIZATION AND ANTIFUNGAL ACTIVITY OF SOME NEWLY SYNTHESIZED SULFUR CONTAINING TRIORGANOTIN(IV) DERIVATIVES

Abstract Triorganotin(IV) complexes having an azomethine linkage have been prepared by the substitution reactions of trimethyl tin chloride with heterocyclic thiosemicarbazones and characterized by elemental analyses, molecular weight determinations and conductivity measurements. On the basis of infrared, 1H, 13C and 119Sn NMR spectroscopy studies, a trigonal bipyramidal geometry for the resulting complexes has been proposed. The nitrogen atom occupies the axial site, while two methyl groups rest in equatorial positions. The antifungal activity of some of the ligands and their metal complexes has also been evaluated against different pathogenic fungi.

Spectral and ESR features of some copper(II) chelates with 2-hydroxyaryloximes

Copper(II) complexes of 2-hydroxyaryloximes were synthesized and characterized on the basis of elemental analyses, molecular weight determinations, conductivity and magnetic moment measurements, and ESR, IR and electronic absorption (in solutions and in solid state) spectroscopy. Implications of the magnetic and spectral data in relation to the structures of the complexes are discussed. Solvent effects are also considered.

SYNTHETIC PATHWAYS, STRUCTURAL FEATURES AND BIOCHEMICAL APPLICATIONS AS STERILIZING AGENTS OF SOME DIPHENYLSILICON(IV) CHELATES WITH N⌢SH SYSTEM

Abstract The synthesis and structural features of some diphenylsilicon(IV) complexes with biologically active organic moieties derived by the condensation of heterocyclic ketones with thiosemicarbazide have been described. The newly resulting products of the types Ph2Si(N⌢S)Cl and Ph2Si(N⌢S)2 were obtained by the 1:1 and 1:2 stoichiometric interactions of diphenyldichlorosilane with the Na-salts of sulfur donor ligands (N⌢SH) in anhydrous methanol. The penta- and hexa- coordinated environment around the silicon(IV) ion have been assigned on the basis of electronic, IR, 1H NMR and 13C NMR spectral studies as well as physicochemical techniques including molecular weight determinations and conductance measurements. The results of two silicon(IV) complexes along with one ligand as a sterilizing agent on male-mice have also been produced and tried to correlate with the structures of the chelates.

Antifungicidal, antibacterial and antifertility activities of biologically active heterocyclic thiosemicarbazones and their coordination complexes with the dimethylsilicon moiety

AbstractSynthetic, structural and biological aspects of trigonal‐bipyramidal, Me2Si(NS)Cl and octahedral, Me2Si(NS)2 types of organosilicon (IV) complexes of heterocyclic thiosemicarbazones (NSH) have been described. The complexes were characterized by elemental analysis, molecular weight determination, conductance measurements and electronic, infrared, 1H and 13C NMR spectral studies. Some ligands and their corresponding dimethylsilicon (IV) complexes have been tested for their effects on several pathogenic fungi and bacteria. Two representative complexes have also been found to act as sterilizing agents by reducing the production of sperm in male mice.

SYNTHESIS AND SPECTROSCOPIC STUDIES OF SOME FUNGITOXIC ORGANOLEAD(IV) COMPLEXES OF SULFUR AND NITROGEN DONOR LIGANDS

Abstract Some organolead(IV) complexes derived from biologically active sulfur and nitrogen donor ligands have been synthesized and characterized by elemental analyses, molecular weight determinations and conductivity measurements. The trigonal bipyramidal and octahedral geometries for these complexes have been proposed on the basis of electronic, infrared and NMR (1H and 13C) spectral evidences. The antifungal activity of some of the ligands and their complexes have also been evaluated against Fursarium oxysporum SCW. ex Frics f. sp. Ciceri (Pedwick) subram.

Diorganotin(IV) Adducts with Amine N-Oxides

Abstract Nineteen complexes of diorganotin(IV) dihalides of the general formula R2SnX2·L2 (R = CH3, C2H5, n-C3H7, n-C4H9, n-C8H17, C6H5, C6H5CH2; X = Cl or Br; L = pyridine N-oxide or 2-picoline N-oxide) have been prepared. The monomeric and non-conducting nature of the complexes has been shown by molecular weight and molar conductance measurements. A hexacoordinated structure has been proposed for all the complexes on the basis of IR, UV and 1H NMR spectral data.

Novel 2-(Aryltelluro)Ethylmethyl-Sulfides Synthesis and Ligation with Palladium(II) and Platinum(II)

Abstract 2-(Aryltelluro)ethylmethylsulfide (1), where aryl = 4-MeOC6H4 (a) and 4-EtOC6H4 (b), has been synthesized by reacting sodium aryltellurolate with CICH2CH2SCH3. 1H and 13C NMR spectra indicate the existence of intramolecular Te←S secondary interactions in 1. IR spectra suggest that both the trans and gauche conformations of two CH2 groups coexist, at least in the solid state. (C6H5CN)2PdCl2 and K4PtCl4 react with 1 to give diamagnetic complexes of the type Pd/PtCl2.1. IR, 1Hand 13C NMR data in conjunction with molecular weight and conductivity measurements suggest that 1 in the complexes acts as a bidentate ligand and two CI (cis to each other), S and Te atoms constitute the square planar geometry around Pd/Pt, as supported by electronic spectra.

ChemInform Abstract: Triphenyltellurium(IV) Dithiocarbamates, Xanthates, and Dithiophosphates.

Abstract Ph 3 TeCl reacts with a molar equivalent of a sodium dithiocarbamate, xanthate, or dithiophosphate (S SNa) to give Ph 3 Te(S S) type derivatives. Molecular weight and conductivity measurements in solution suggest that these new triphenyltelluronium compounds are ionized in polar solvents but show a very strong tendency towards ion-association. The IR spectral data suggest that all these sulphur donors are coordinated in the η 1 mode in the new compounds. Their 1 H NMR spectra are characteristic, and are consistent with the monodentate behaviour of the S-ligands. Photolysis of their toluene/benzene/chloroform solutions (∼ 1 to 10 m M ) gives Ph 2 TeO, biphenyl, and disulphide. When O 2 is bubbled through their solutions during photolysis, TeO 2 is also formed. The rates of the UV-promoted decomposition decreases in the order xanthate > dithiocarbamate > dithiophosphate.

Synthesis and Characterization of Boron Complexes of Some Biologically Active Ligands

Abstract Boron complexes LB-O-B(OAc)2 and LB-O-BL with Schiff bases (LH2) having and donor systems have been prepared from oxybis(diacetoxy)borane. The compounds have been characterized by elemental analysis, molecular weight determination and conductivity measurements. The mode of bonding of the ligands with the boron atom has been determined on the basis of IR, 1H NMR, 11B NMR and electronic spectral studies.

Triphenyltellurium(IV) dithiocarbamates, xanthates, and dithiophosphates

Ph 3TeCl reacts with a molar equivalent of a sodium dithiocarbamate, xanthate, or dithiophosphate (S SNa) to give Ph 3Te(S S) type derivatives. Molecular weight and conductivity measurements in solution suggest that these new triphenyltelluronium compounds are ionized in polar solvents but show a very strong tendency towards ion-association. The IR spectral data suggest that all these sulphur donors are coordinated in the η 1 mode in the new compounds. Their 1H NMR spectra are characteristic, and are consistent with the monodentate behaviour of the S-ligands. Photolysis of their toluene/benzene/chloroform solutions (∼ 1 to 10 m M) gives Ph 2TeO, biphenyl, and disulphide. When O 2 is bubbled through their solutions during photolysis, TeO 2 is also formed. The rates of the UV-promoted decomposition decreases in the order xanthate > dithiocarbamate > dithiophosphate.

Palladium(II) Complexes of Biologicaily Active Thicsemicarbazones and Semicarbazones

Abstract Reactions of palladium chloride and Schiff bases having the donor groups NSH and NOH have resulted in complexes of the type[Pd(NXH)2]Cl2 and [Pd(NX)2] (where X = N or S). The resulting derivatives have been characterised on the basis of elemental analyses, molecular weight determinations and conductivity measurements, IR, 1H NMR and electronic spectral studies.

Arylbis(thiosemicarbazone)tellurium(II) chlorides; three coordinate tellurium(II) complexes

Three coordinate tellurium(II) complexes of the type [ArTe(XTSC) 2]Cl, where Ar = C 6H 5, 4-HOC 6H 4 or 4-CH 3OC 6H 4 and XTSC = thiosemicarbazone of benzaldehyde, acetophenone, salicylaldehyde or 2-hydroxyacetophenone, have been synthesized by treating ArTeCl 3 with the thiosemicarbazones in aqueous methanol. Molecular weight and conductivity measurements suggest that the chlorine in these complexes is ionic. The IR, 1H and 13C NMR data suggest that coordination of the XTSC is through sulphur alone, probably giving three coordinate tellurium in [ArTe(XTSC) 2] +. The nature ot TeS bonding and the stability of the complexes is discussed.

ChemInform Abstract: Synthesis and Structural Features of Organo Si(IV) Imine Complexes.

Abstract Complexes of the general formula, Me2SiL2 (where, LH = semi- and thiosemicarbazones) have been prepared by reacting dimethylsilicondichloride with the ligand in a 1 : 2 (metalloid : ligand) molar ratio. These complexes have been characterized by elemental analysis, molecular weight determinations and conductivity measurements, and structures have been proposed using electronic, IR, 1H NMR and 13C NMR spectral studies. The data suggest that the ligands function as monobasic bidentate towards the metalloid atom.

Large transition metal clusters—VI. Ligand exchange reactions on Au 55(PPh 3) 12Cl 6—the formation of a water soluble Au 55 cluster

The cluster compound Au 55(PPh 3) 12Cl 6 is soluble in organic solvents like pyridine or dichloromethane but decomposes rapidly thus precluding crystal growth and other investigations. Exchange of PPh 3 in Au 55(PPh 3) 12Cl 6 by Ph 2PC 6H 4SO 3Na takes place quantitatively and yields the stable water soluble cluster Au 55(Ph 2PC 6H 4SO 3Na·2H 2O) 12Cl 6. Molecular weight determinations and conductivity measurements in H 2O show that the cluster is completely dissociated into 12Na + and [Au 55(Ph 2PC 6H 4SO 3) 12] 12-. From such aqueous solutions very small, probably crystalline particles are obtained which can, in the dried state, be observed in the transmission electron microscope using a 100 kV electron beam. Here we present images that show columns or layers of cluster molecules with a distance of 2.1± 0.1 nm. The diameters of a cluster molecule including the ligand shell and of the naked cluster are calculated as 2.2±0.1 and 1.3–1.4 nm, respectively. It is concluded that the cluster molecules, forming the layered structures, are intact. This is the first time that M 55 clusters could be imaged with an intact ligand shell by means of TEM. Earlier microscopic investigations with a 400 kV beam gave high resolution images of the cluster nuclei only.