N. K. Kaushik

Bis(indenyl)titanium(IV) and zirconium(IV) complexes of monofunctional bidentate salicylidimines

Abstract Dichlorobis(indenyl)-titanium(IV) and -zirconium(IV), (C9H7)2TiCl2 and (C9H7)2ZrCl2, react with bidentate Schiff bases such as salicylidene aniline, salicylidene-o-toluidine, salicylidene-m-toluidine and salicylidene-p-toluidine in a 1:1 molar ratio in refluxing tetrahydrofuran in the presence of triethylamine to yield complexes of the type (C9H7)2Ti(SB)Cl and (C9H7)2Zr(SB)Cl, respectively where SB is the anion of the corresponding Schiff base, SBH. The new derivatives have been characterised on the basis of their elemental analyses, conductance measurements and spectral (IR, 1H NMR and electronic) studies.

Halide and complex halogeno anions as salts of oxinate chelates of titanium(IV)

Abstract (η 5 -Cyclopentadienyl)(η 5 -pyrrolyl)titanium(IV) dichloride, (η 5 -indenyl)-(η 5 -pyrrolyl)titanium(IV) dichloride and (η 5 -cyclopentadienyl)(η 5 -indenyl)-titanium(IV) dichloride, when treated with 8-hydroxyquinoline (oxine) in aqueous medium form ionic derivatives of the type, [(η 5 -R)(η 5 -R′)TiL] + Cl - (R = C 5 H 5 , C 9 H 7 , R′ = C 4 H 4 N; R = C 5 H 5 , R′ = C 9 H 7 ; L is the conjugate base of (oxine). A number of halide and complex halogeno anions present in aqueous solution were isolated as salts of these ionic complexes giving derivatives of the type, [(η 5 -R)(η 5 -R′)TiL] + X - (X = Br - , I - , ZnCl 3 (H 2 O) - , CdCl 4 2- , HgCl 3 - ). Conductivity measurements in nitrobenzene solution indicate that these complexes are electrolytes. Both the IR and 1 H NMR spectral studies demonstrate that the ligand L is chelating. Consequently there is tetrahedral coordination about the titanium(IV) ion.

Some Tribenzyl Tin(IV) Complexes with Thiohydrazides and Thiodiamines. Synthesis, characterization and thermal studies

Tribenzyl tin(IV) chloride complexes of morpholine N-thiohydrazide (L1), aniline-N-thiohydrazide (L2),N-(morpholine-N-thio)-1,3-propanediamine (L3) and (aniline-N-thio)-1,3-propanediamine (L4) of the type (C6H5CH2)3Sn(L)Cl (where L=L1, L2, L3 and L4) have been synthesised in dioxane and in H2O and acetone mixture. These were characterized by C,H,N-analysis, UV, IR and 1HNMR spectral studies. In both the complexes ligands act as bidentate, coordinating through sulphur and terminal nitrogen. The complexes are 1:1 metal ligand complexes. Various thermodynamic parameters have been calculated for the decomposition steps using TG/DTA curves in air as well as nitrogen atmosphere.

Comparison of the prevention of aflatoxin B1-Induced genotoxicity by quercetin and quercetin pentaacetate

Earlier work carried out in our laboratory highlighted the mode of action of acetoxy 4-methylcoumarins in preventing the genotoxicity of aflatoxin B(1) (AFB(1)). We have in this report extended the observations to quercetin pentaacetate (QPA), which unlike quercetin (Q) has demonstrated time-dependent inhibition of liver microsome catalysed AFB(1) epoxidation as measured by AFB(1) binding to DNA. The action of QPA is similar to that of the acetoxy 4-methylcoumarins in that they are acted upon by microsomal transacetylase leading to modulation of catalytic activities of certain enzymes (such as P-450 enzymes, NADPH cytochrome C reductase and glutathione S-transferase) possibly by way of protein acetylation. In the present work, we have documented the transacetylase-mediated action of QPA in preventing genotoxicity due to AFB(1).

Tris-Nethyl, m-tolyl)dithiocarbamato complexes of arsenic(III), antimony(III) and bismuth(III)

Abstract Tris-N(ethyl, m-tolyl) dithiocarbamato complexes of arsenic(III), antimony(III) and bismuth(III) abbreviated as As(S2CNRR′)3 Sb(S2CNRR′)3 and Bi(S2CNRR′)3, respectively, where R  C2H5 and R′  m-C6H4CH3, have been synthesized. These complexes have been characterized on the basis of elemental analyses, molecular weight determinations, conductance measurements and infrared spectral studies. Thermal studies of these complexes have been carried out in nitrogen and air to determine their modes of decomposition. Kinetic parameters, such as apparent activation energy and order of reaction, have been determined by the graphical method of Coats and Redfern [1].

Synthesis and Characterisation of Bis(η5-Fluorenyl)N,N-disubstituted-dithiocarbamatochlorotitanium(IV) and Zirconium(IV) Componds

Abstract Some bis(η5-fluorenyl)N,N-disubstituteddithiocarbamatochloro-titanium(1V) and zirconium(1V) compounds of the type (η5-C13H9)2 Ti(S2CNRR1)Cl and (η5-C13H9)2 Zr(S2CNRR1)Cl (where R = alkyl and R′ = aryl or cyclohexyl) have been prepared by the reaction of bis(η5 -fluorenyl)titaniun(IV)dichloride and bis(η5-fluorenyl)zirconium(IV)dichloride with the sodium salt of N,N-disubstituted dithiocarbamates. A study of molecular weight, conductance, infrared spectra and magnetic susceptibility in addition to elemental analysis has been carried out to throw some light on the probable structure of these derivatives. These studies show that the complexes are monomeric, non-electrolytes in which the dithiocarbamate group acts as a bidentate ligand.

Thermal studies on titanyl and zirconyl oxalates. A review

Abstract Past work covering the year 1983 on the thermal studies on titanyl and zirconyl oxalates is reviewed.

Reactions of Dichlorobis (Cyclopentadienyl) Titanium (IV) with Bident Ate Schiff Bases Derived from Salicylaldehyde and 4-Substituted Anilines

Abstract Dichlorobis (cyclopentadienyl) titanium(IV), Cp2TiCl2, reacts with bidentate Schiff bases such as salicylidene-4-anisidine, salicylidene-4-phenetidine, salicylidene-4-bromoaniline, salicylidene-4-iodoaniline and salicylidene-4-nitroaniline in a 1:1 molar ratio in refluxing tetrahydrofuran in the presence of trimethylamine, to yield Cp2Ti (SB)Cl, where (SB)− is the anion of the corresponding Schiff base, SBH. The derivatives have been characterised on the basis of their elemental analyses, molecular weights, conductance and spectral (IR, 1H NMR and electronic) characteristics.

Titanium(IV) and Zirconium(IV) Dithiocarbamates

Abstract Mono-, bis-, tris- and tetrakis-dithiocarbamato derivatives of titanium(IV) and zirconium(IV) tetrachlorides of the type M(S2CNRR1)n Cl4-n(n = 1–4, R = C2H5, R1 = C6H4CH3; R = H, R1 = C5H9 or C7H13) have been prepared in refluxing dichloromethane. These complexes have been characterized on the basis of elemental analyses, molecular weight determinations, conductance measurements, magnetic moment data, and spectral (i.r., electronic and proton magnetic resonance) studies. Dithiocarbamate ligands are bidentate in nature in these complexes. Five-, six-, seven- and eight-coordination numbers are reported for titanium(IV) and zirconium(IV) in their mono-, bis-, tris- and tetrakis-dithiocarbamato complexes, respectively.

Phthiocol Chelates of Bis(Cyclopentadienyl)titanium(IV)

Abstract A convenient method for the preparation of [Cp2TiL]+ X-complexes, where L is the conjugate base of 3-hydroxy-2-methyl-1,4-naphthaquinone or phthiocol, X− [dbnd] Br−, I−, ZnCl3(H2O)−, ROCS− 2 or R2NCS− 2 (R [dbnd] Me, Et or i-Pr) have been described. The complexes have been characterized on the basis of chemical analyses, electrical conductance and infrared spectral studies. These studies indicate that the complexes are 1:1 electrolytes in which the ligand L is chelating through the hydroxy and carbonyl oxygens of the phthiocol group.