Indian Journal of Chemistry

Sect. A: Inorganic, Bio-inorganic, Physical, Theoretical & Analytical

 

VOLUME 41A

NUMBER 3

MARCH 2002

CONTENTS

                                                                   Papers

 

457

Exponent-dependent properties of the connectivity index

 

 

Ivan Gutman*, Mirko Lepović ,
Dušica Vidović &
Lane H Clark

 

 

 

 

462

 

A quantum chemical study of the physical process of planar (D3h) to pyramidal (C3v) structural reorganization of boron trifluoride molecule

                                    

 

 

 

                                       

Dulal C Ghosh*, Jibanananda Jana & Arindam Chakraborty

 

 

Boron trifluoride molecule occurs in planar(D3h) form and it reorganizes quickly to C3v shape in chemical response from donor molecules in order to form adduct super molecules. This structural reorganization is studied by quantum mechanical localized molecular orbital and energy partitioning methods.

 

 

 

472

 

Influence of pH and supporting electrolyte on

electrochemical reduction of CO2 using nickel

(II)macrocyclic complex of 1, 3, 6, 9, 11, 14 - hexaazacyclohexadecane as catalyst at HMDE

 

 

 

 

 

M Aulice Scibioh, B Viswanathan* &
V R Vijayaraghavan

 

 

 

 

478

 

Electrochemical studies on Dowex-50 membrane using sodium chloride and urea solutions having variable composition

 

 

Kehar Singh*, A K Tiwari & Chandra Shekhar Dwivedi

 

 

Membrane potential and membrane conductance studies using Dowex –50 membrane and sodium chloride- urea solutions of variable composition have been carried out. These studies show that the presence of even non-electrolyte alters permselective behaviour of the ion exchange membrane because of reduced coion exclusion as a result of the accompanying deswelling of the membrane matrix.

 

483

 

Transport studies of  ion – solvent  interactions in acetonitrile – rich regions of  benzene and ethanol

 

 

 

M S Chauhan*, K Sharma & G Kumar

 

 

Molar conductance and viscosity of Bu4NBPh4, NaBPh4, Bu4NBr, Bu4NI, LiClO4 and NaClO4 have been reported in acetonitrile (ACN)–rich regions of benzene and ethanol (EtOH) at 25oC. The analysis of the data show that Bu4N+ and Ph4B- lose their spherical shape, while Li+, Na+, Br-, I- and ClO4- behave as spherical entities during viscous flow process.

 

489

 

Kinetic and mechanistic studies on the interaction of uridine with hydroxopentaaquarhodium (III) ion

 

S K Mukhopadhyay & A K Ghosh*

 

 

 

         KE

[Rh(OH2)5(OH)]2+ + uridine Û Rh(OH2)5(OH)]2+.uridine

                outersphere association                                                            complex

                 ka

[Rh(OH2)5(OH)]2+. Uridine ®  [Rh(OH2)4(OH)(uridine)]2+ + H2O

 

 

493

 

Correlation analysis of reactivity in the oxidation of substituted benzyl alcohols

by quinolinium fluorochromate

 

 

Itishri Dave, Vinita Sharma &
Kalyan K Banerji
*

 

 

 

Oxidation of benzyl alcohol and some ortho-, meta- and  para-monosubstituted ones by quinolinium fluorochromate in dimethyl sulphoxide leads to the formation of corresponding banzaldehydes.   The oxidation of para-substituted benzyl alcohols is more susceptible to the delocalization effect than that of ortho- and meta- substituted compounds, which display a greater dependence on the field effect.

 

500

 

 

 

Exchange kinetic studies on zirconium antimonophosphate

 

 

S K Mittal* & Pritpal Singh

 

 

Exchange kinetics of the alkaline earth metal ions with labile protons of the synthetic ion exchanger zirconium antimonophosphate has been studied, using the limited bath technique. Effect of concentration, particle size and temperature on the extent of exchange at the solution-solid interface are reported. The studies indicate that the effective diffusion coefficient consists of an initial fast exchange and later a slow exchange, representing the inter-diffusion of counter ions through the pores of the exchanger matrix.

506

 

Synthesis and characterization of azaphosphole complexes of ruthenium and rhodium

 

 

 

Vimal K Jaina, Leena Hemrajani &
Raj K Bansal

 

 

513

 

Structural studies on some trifluoro-b-diketonates of tin(IV) and lead(II)

 

 

 

 

 

 

Sudha Singh & Vishnu D Gupta*

 

 


521

 

Studies on the determination of palladium(II) by fluorescence quenching method with meso-tetra[4-carboxymethylenoxy)phenyl]porphyrin

 

 

Yan-jun Fang, Hui Chen,* Zhi-xian Gao & Xiao-yong Jin

 

 

Notes

525

 

Phenol–amide chelates of iron (III) as catalysts for hydrolysis of active esters

 

 

Harapriya Rath, Guru C Pradhan, Prakash Mohanty & Anadi C Dash*

 

 

The iron(III) chelate of 1,2-bis (2-hydroxybenzamido) ethane catalyses the hydrolysis of p-nitrophenol acetate

528

An enhancement in the thermal stability and acidity of hydrous zirconia in presence of
12-tungstophosphoric acid

 

 

Shirish Patel & Anjali Patel*

 

12-Tungstophosphoric acid supported on hydrous zirconium oxide has been prepared and characterized.

532

A kinetic study of the chemical oscillating system comprising mannitol-acetone-bromate-H2SO4

Shi-Gang Shen*, Han-Wen Sun,
Jin-Huan Shan & Jun-li Liu

 

A new type of  chemical oscillating system comprising mannitol-acetone-bromate-H2SO4 has been studied by the potential method.

537

 

Kinetics of acid-promoted dissociation  reactions of Cu [Ph4(14) tetraene N4] macrocyclic complex

 

 

A K Singh*, Rupam Singh & Seema Baniwal

 

 

541

Correlation analysis of reactivity in the
oxidation of substituted benzylamines by benzyltrimethylammonium tribromide

 

 

Rekha Sankhla & Seema Kothari*

 

 

The oxidation of benzylamine and twenty-seven ortho-, meta- and para-monosubstituted benzyl- amines by benzyltrimethylammonium tribromide, in dimethylsulphoxide, leads to the formation of corresponding aldimines. The oxidation of para-substituted benzylamines is more susceptible to the delocalization effect than is the oxidation of ortho- and meta-substituted compounds.

547

 

Kinetics and mechanism of the
 ruthenium (III) - catalysed oxidation of some glycols by cerium (IV) in sulphuric acid medium

                                                               

 

 

                                               

Bharat Singh*, Meera Singh &
Deepmala Kesarwan

 

S+Ru(VIII)   Intermediate                             Intermediate ®  F+2H++Ru(VI)                      
   F`+Ce(IV)    Product+H++Ce(III)                

Ru(VI)+Ce(IV)    ®    Ru(VII)+Ce(III)                  Ru(VII)+Ce(IV)    Ru(VIII)+Ce(III)            

 

550

 

Synthesis and characterization of palladium(II) complexes containing
N-pyridiniodithiophosphinates

 

Vimal K Jain*, Leena Hemrajani &
Raj K Bansal

 

 

554

 

Synthesis, magnetic and spectral studies of some cis-dioxomolybdenum(VI) complexes derived from N, O- and N2O2- type Schiff bases

 

 

 

 

 

 

R C Maurya*, B Shukla, & A Pandey

 

 

560

 

Synthesis and characterization of
ruthenium(II) complexes of different types
 of potential unsymmetrical hemilabile P-O and P-S donors ligands

 

 

 

 

Pankaj Das, Manab Sharma, Nandini Kumari, Dilip Konwar & Dipak Kumar Dutta*

 

 

563

 

A spectrophotometric method for the trace determination of vanadium as V(V)-5-chloro-8-hydroxy-7-iodoquinoline in aqueous medium

 

 

Vanita Sharma, Monica Nijhawan &
A L J Rao*

 

 

A simple and rapid spectrophotometric method for the determination of vanadium(V) is developed in the presence of 5-choloro-8-hydroxy-7-iodoquinoline under acidic conditions using Triton X-100 as surfactant. The applicability of the method has been tested by analysis of a large number of different synthetic and commercial samples.

 

Book Review

565

Metal Ions in Biological Systems,
Vol. 38(Editors: A. Sigel and H. Sigel)

 

D Banerjea

 

 

Authors for correspondence are indicated by (*)

 

 

 

 

 

Papers

Indian Journal of Chemistry
Vol. 41A March  2002, pp. 457-461

 

Exponent-dependent properties of the connectivity index

Ivan Gutman, Mirko Lepović , Dušica Vidović &Lane H Clark

The connectivity index is defined as C(l) =S(dudv)l, where dv is the degree of the vertex v of the respective molecular graph, and where the summation embraces all pairs of adjacent vertices. The exponent l is usually chosen to be equal to -0.5 but other options have been considered as well, especially C(-1). We show that whereas C(-0.5) correctly reflects the extent of branching of the carbon-atom skeleton of organic molecules, and is thus a suitable topological index for modelling physico-chemical properties of the respective compounds, this is not the case when the exponent l assumes larger negative values, in particular when l=-1. The value of l is established beyond which C(l) fails to be a measure of molecular branching.

 

 

Indian Journal of Chemistry
Vol. 41A March  2002, pp. 462-471

 

 

A quantum chemical study of the physical process of planar (D3h) to pyramidal (C3v) structural reorganization of boron trifluoride molecule

 

Dulal C Ghosh, Jibanananda Jana & Arindam Chakraborty.

The dynamic process of planar (D3h) to pyramidal (C3v) reorganization prior to the event of chemical reaction of boron trifluoride, BF3, molecule has been studied by localized molecular orbital and energy partitioning methods.  The energy of reorganization, the stretching of B—F bond and alteration of charge density distribution are computed for a wide range of molecular conformations generated by deforming the equilibrium geometry of the molecule. The large activation barrier of the molecule is correlated to its high energy of reorganization prior to the event of chemical reaction due to the elimination of partial double bond character and the weakening of the B—F bond on to stretching. The B—F bond stretches through 0.023Aºº. The bonding in the equilibrium geometry is computed in terms of localized molecular orbitals, LMO's. The quantum mechanical hybridization of orbitals on B and F atoms forming the s-(B—F) bond is computed for all the conformations of the molecule through the generated LMO's.  The total energy of the molecule at all its conformations is decomposed into one- and two center components. The weakening of the B—F bond and variation of the percentage of the s-characters of the hybrids on B and F atoms forming the bond in a series of conformations are correlated and has been found to be in accordance with Coulson’s observation in similar situation. 

 

 

Indian Journal of Chemistry
Vol. 41A March  2002, pp. 472-477

 

Influence of pH and supporting electrolyte on electrochemical reduction of CO2 using nickel (II) macrocyclic complex of 1, 3, 6, 9, 11, 14 - hexaazacyclohexadecane as catalyst at HMDE

 

M Aulice Scibioh, B Viswanathan & V R Vijayaraghavan

 

Electrochemical studies on the title compound using cyclic voltammogram (CV) and control potential electrolysis (CPE) techniques reveal that it reduces CO2 electrocatalytically at -1.36V/SCE at hanging mercury drop electrode (HMDE) in aqueous medium using LiClO4 as a supporting electrolyte.    The products are found to be CO and H2 in 3:2 mole ratio in the gaseous phase as detected using gas chromatography (GC) and trace amounts of formic acid in solution phase as detected using colorimetric technique.   The Ik/ Id values (where Ik is the kinetic current measured in the presence of CO2 and Id is the diffusion current measured in N2 atmosphere) observed at various pH values show that pH 5.0 is best suited for CO2 reduction.  In addition, the hydrophobicity/ hydrophilicity near the electrode surface provided by the cation of the supporting salt and its influence on CO2 reduction is discussed.

 

 

Indian Journal of Chemistry
Vol. 41A March  2002, pp. 478-482

 

Electrochemical studies on Dowex-50 membrane using sodium chloride and urea solutions having variable composition

Kehar Singh, A K Tiwari & Chandra Shekhar Dwivedi

Membrane potential and membrane conductance measurements have been carried out using Dowex-50 - Kynar membrane, sodium chloride and urea mixtures of variable compositions to examine the effect of non-electrolytic constituent of the mixture on electrochemical character of the membrane. A significant change in membrane permselectivity is observed in the presence of urea due to changed coion exclusion because of the accompanying alteration in the swollen state of the membrane matrix.

 

 

 

 

Indian Journal of Chemistry
Vol. 41A March  2002, pp. 483-488

 

 

 

Transport studies of ion – solvent interactions in acetonitrile – rich regions of benzene and ethanol

 

M S Chauhan, K Sharma & G Kumar

 

Molar conductance and viscosity of Bu4NBPh4, NaBPh4, Bu4NBr, Bu4NI, LiClO4 and NaClO4 have been reported in acetonitrile (ACN)–rich regions of benzene and Ethanol (EtOH) at 25oC. The conductance data have been analyzed in terms of limiting molar conductance (Lo) and ion-association constant (KA) using Shedlovsky conductance equation. The viscosity data have been analyzed in terms of viscosity A and B-coefficients of the Jones- Dole viscosity equation. Both Lo and B-coefficients have been resolved into ionic components i.e., limiting molar ionic conductance, (lio) and (B±) values for various ions on the basis of Bu4NBPh4 assumption. The effective ionic radii (ri) of Bu4N+, Ph4B-, Li+, Na+, Br-, I- and ClO4- have been determined from lio values using Gill’s modification of the Stokes’ law. The ionic B± values for these ions have also been discussed in terms of Einstein’s equation. The analysis of the data show that Bu4N+ and Ph4B- lose their spherical shape, while Li+, Na+, Br-, I- and ClO4- behave as spherical entities during viscous flow process.

 

 

 

 

Indian Journal of Chemistry
Vol. 41A March  2002, pp. 489-492

 

Kinetic and mechanistic studies on the interaction of uridine with
hydroxopentaaquarhodium (III) ion

 

S K Mukhopadhyay & A K Ghosh

Kinetics of interaction between uridine and [Rh(H2O)5OH]2+ has been studied spectrophotometrically as a function of [Rh(H2O)5OH2+], [uridine], pH and temperature. The reaction has been monitored at 290 nm, the lmax of the substituted complex and where spectral difference between the reactant and product is maximum. The reaction rate increases with [uridine] and reaches limiting value at higher ligand concentration. From the experimental findings an associative interchange mechanism for the substitution process is suggested. The activation parameters (DH¹ = 46.5 ± 1.4 kJ mol-1, DS¹ =-181 ± 4 J K-1mol-1) support the proposition. The negative DGo (-15.1 kJ mol-1) for the first equilibrium step also supports the spontaneous formation of an outersphere association complex.

 

 

Indian Journal of Chemistry
Vol. 41A March  2002, pp. 493-499

 

Correlation analysis of reactivity in the oxidation of substituted benzyl alcohols by quinolinium fluorochromate

 

Itishri Dave, Vinita Sharma & Kalyan K Banerji

Oxidation of benzyl alcohol and some ortho-, meta- and para-monosubstituted ones by quinolinium fluorochromate (QFC) in dimethyl sulphoxide (DMSO) leads to the formation of corresponding banzaldehydes.  The reaction is first order each in both QFC and the alcohol. The reaction is promoted by hydrogen ions; the hydrogen‑ion dependence has the form kobs= a + b  [H+]. Oxidation of a,a‑dideuteriobenzyl alcohol  (PhCD2OH) has exhibited a substantial primary kinetic   isotope effect. The reaction has been studied in nineteen organic solvents and the effect of solvent analysed using Taft's  and  Swain's multi-parametric equations.  The rates of oxidation of para‑ and meta‑substituted benzyl alcohols have been correlated in terms of Charton’s triparametric LDR equation whereas the oxidation of ortho-substituted benzyl alcohols with tetraperametric LDRS equation. The oxidation of para-substituted benzyl alcohols is more susceptible to the delocalization effect than that of ortho- and meta- substituted compounds, which display a greater dependence on the field effect. The positive value of h suggests the presence of an electron-deficient reaction centre in the rate-determining step. The reaction is subjected to steric acceleration by the ortho-substituents. A suitable mechanism has been proposed.

 

Indian Journal of Chemistry
Vol. 41A March  2002, pp. 500-505

 

 

Exchange kinetic studies on zirconium antimonophosphate

 

S K Mittal & Pritpal Singh

 

Exchange kinetics of the alkaline earth metal ions with labile protons of the synthetic ion exchanger zirconium antimonophosphate has been studied, using the limited bath technique. Effect of concentration, particle size and temperature on the extent of exchange at the solution-solid interface are reported. The Boyd method for studying the kinetics of spherical particles is used to explain the results. Distinction between particle diffusion and film diffusion has been made by interruption test. The overall studies indicate that the effective diffusion coefficient consists of two components, an initial fast exchange and later a slow exchange, representing the inter-diffusion of counter ions through the pores of the exchanger matrix. With increase in temperature, the contribution of the faster component decreases, probably because the metal ions diffuse as dehydrated ions and the dehydration of the metal ions is easy at lower temperature. The effect of concentration and particle size on the exchange rate are also discussed.

 

Indian Journal of Chemistry
Vol. 41A March  2002, pp. 506-512

 

 

Synthesis and characterization of azaphosphole complexes of ruthenium and rhodium :

Vimal K. Jain*, Leena Hemrajani & Raj K Bansal

 

Reaction of azaphospholes (L) [2-phosphaindolizines (1) and 1,3-azaphospholo[5,1-a]isoquinolines (2)] with [h5-Cp*RhCl2]2 (Cp* = pentamethylcyclopentadienyl) and [Ru(h6-cymene)Cl2]2 in 2:1 molar ratio in dichloromethane yields mononuclear complexes of the type [Cp*RhCl2(L)].H2O and [Ru(cymene)Cl2(L)].H2O. These complexes were characterized by elemental analysis, FAB mass, IR and NMR (1H and 31P) spectral data. Stereochemistry of these complexes has been discussed based on NMR data.  NMR studies revealed a dynamic equilibrium between covalent and ionic forms of the complexes derived from 1 in solution.

 

 

Indian Journal of Chemistry
Vol. 41A March  2002, pp. 513-520

 

Structural studies on some trifluoro-b-diketonates of tin(IV) and lead(II)

 

Sudha Singh & Vishnu D Gupta

Organotin(IV), tin(IV) and lead(II) trifluoro-b-diketonates have been prepared and characterized on the basis of IR, 1H and 13C NMR data. All the organotin(IV) complexes are thermally stable liquids. SnCl2(CF3COCHCOPh)2 (7) is characterized by X-ray crystallography which reveals a distorted cis-octahedral structure. X- ray diffraction analysis of Pb(CF3COCHCOC6H4-p-Cl)2 (8) shows a highly distorted trigonal bipyramidal structure.

 

Indian Journal of Chemistry
Vol. 41A March  2002, pp. 521-524

 

 

 

Studies on the determination of palladium(II) by flourescence quenching method with meso-tetra[4-(carboxymethylenoxy)phenyl]porphyrin

 

Yan-jun Fang,  Hui Chen, Zhi-xian Gao & Xiao-yong Jin

 

  The spectrofluorimetric determination of Pd(II) using meso-tetra[4-(carboxymethylenoxy)phenyl]porphyrin (TCMOPPH2) as an emission reagent has been investigated by measuring the decrease of its fluorescence intensity of the complexation of Pd(II)-TCMOPP. An emission peak of TCMOPPH2, which is decreased linearly by adding of Pd(II), occurs at 394nm in aqueous solution with excitation at 306nm.The fluorescence intensity vary linearly with the concentration of palladium(II) in the range 3.754×10-3~0.3625mg/mL (SD = 0.034 for 10 times measurements) and the detection limit down to 2.715×10-4 mg/mL. The interference of other noble metals and some of inorganic ions have been described, and the quenching mechanism has also been investigated according to the Stern-Volmer equation.

 

 

Notes

 

 

 

Indian Journal of Chemistry
Vol. 41A March  2002, pp. 525-527

 

Phenol–amide chelates of iron (III) as catalysts for hydrolysis of active esters

Harapriya Rath, Guru C. Pradhan, Prakash Mohanty & Anadi C. Dash

 

The hydrolysis of p-nitrophenylacetate has been studied in the presence of mononuclear iron(III) chelates of 1,2-bis(2-hydroxybenzamido)ethane(I), 1,3-bis(2-hydroxybenzamido)pro-pane(II),  1,5-bis(2-hydroxybenzamido)-3-aza-pentane(III), and 1,8-bis(hydroxybenzamido)-3,6-diazaoctane(IV) in 10 % (v/v) MeOH +H2O medium at pH = 8.3 – 9.5 (borate buffer), 26.5 ± 0.2ºC, and I = 0.1 mol dm-3. The amide NH-deprotonated chelate of I has been found to be the most effective catalyst. Catalysis is attributed to both FeIII-OH and FeIIIN(CO)R moieties of this chelate. The catalytic efficiency decreases with chelate ring expansion and the steric effects of the multidenate ligands. The results further indicate that the metal-bound amide function and its deprotonated form are of much reduced activity as compared to metal-bound hydroxo group.

 

 

 

Indian Journal of Chemistry
Vol. 41A March  2002, pp. 528-531

An enhancement in the thermal stability and acidity of hydrous zirconia in presence of 12-tungstophosphoric acid.

 

Shirish Patel & Anjali Patel

 

A new solid acid catalyst, 12- tungstophosphoric acid, has been prepared, supported on hydrous zirconium(IV) oxide and designated as PW/Z. The solid catalyst as well as zirconium(IV) oxide have been characterized by chemical analysis, chemical stability, ion exchange capacity, FTIR, TGA and surface area measurement(BET method). The catalytic activity has been examined by carrying out esterification as a model reaction.

 

 

 

Indian Journal of Chemistry
Vol. 41A March  2002, pp. 532-536

 

 

A kinetic study of the chemical oscillating system comprising mannitol-acetone-bromate-H2SO4

Shi-Gang Shen, Han-Wen Sun, Jin-Huan Shan & Jun-li Liu

 

A new type of chemical oscillating system comprising mannitol-acetone-bromate-H2SO4 has been studied by the potential method. The initial concentration range of the reactants in the oscillating system and affecting factors have been examined. The empirical equation of the induction period and oscillating cycle with the concentrations of the reactants and temperature has been obtained. The apparent activation parameters corresponding to the induction period, oscillating cycle and oscillating life, Ei, Ep, El are 45.14 kJ mol-1, 60.20 kJ mol-1 and 67.30 kJ mol-1, respectively. The oscillating characteristic and possible oscillation mechanism have been analyzed.

 

 

 

Indian Journal of Chemistry
Vol. 41A March  2002, pp. 537-540

 

Kinetics of acid-promoted dissociation reactions of Cu [Ph4(14)

tetraene N4] macrocyclic complex

 

A.K. Singh, Rupam Singh & Seema Baniwal

 

The kinetics of acid-promoted dissociation reactions of copper complex of 2,4,9,11-tetraphenyl-1,5,8,12-tetraazacyclotetradeca-1,4,8,11-tetraene abbreviated as Cu [Ph4(14) tetraene N4], has been studied spectrophotometrically under pseudo-first order conditions with HCl, HNO3 and H3PO4 in methanol, acetonitrile and dimethylformamide at temperatures 30-45 ± 0.1 oC. First order kinetics have been observed in all the cases. The rate constant values of Cu [Ph4(14) tetraene N4] increase linearly with acid concentration and the reaction proceeds faster in media of higher dielectric constants. The rate of reactions decreases with the decrease in the acid strength (HCl > HNO3 > H3PO4). A mechanism with the acid dependent reaction of the activated species [M(L*)]2+ has been proposed. Product analysis shows that the product is the protonated ligand.

 

 

Indian Journal of Chemistry
Vol. 41A March  2002, pp. 541-546

 

Correlation analysis of reactivity in the oxidation of substituted benzylamines by benzyltrimethylammonium tribromide

Rekha Sankhla & Seema Kothari

The oxidation of benzylamine and twenty-seven ortho-, meta- and para-monosubstituted benzylamines by benzyltrimethylammonium tribromide (BTMAB), in dimethylsulphoxide (DMSO), leads to the formation of corresponding aldimines. The reaction is first order with respect to both BTMAB and the amine. The oxidation of deuterated benzylamine exhibited a substantial kinetic isotope effect. Addition of benzyltrimethylammonium bromide does not affect the rate. Tribromide ion has been postulated as the reactive oxidizing species. The rates of the oxidation of para- and meta-substituted benzylamines showed excellent correlation in terms of both Taft’s dual substituent-parameter and Charton’s triparametric LDR equations, whereas the ortho-substituted compounds exhibited the best correlation with the Charton’s tetraparametric LDRS equation. The oxidation of para-substituted benzylamines is more susceptible to the delocalization effect than is the oxidation of ortho- and meta-substituted compounds, which display a greater dependence on the field effect. The low positive value of the h suggests the presence of an electron-deficient centre in the rate-determining transition state with less charge separation. A suitable mechanism has been proposed.

 

 

 

Indian Journal of Chemistry
Vol. 41A March  2002, pp. 547-549

 

 

Kinetics and mechanism of the ruthenium (III) - catalysed oxidation of some glycols by cerium (IV) in sulphuric acid medium

 

Bharat Singh, Meera Singh & Deepmala Kesarwani

 

The ruthenium(III) catalysis in ceric sulphate oxidation of methyl glycol (MG), ethylene glycol (EG), propylene glycol (PG) and 1,3-butylene glycol (BG) in sulphuric acid medium was investigated. The reactions were found to be zero order with respect to cerium(IV) ion and hydrogen ion. Zero order dependence of [Ce (IV)] clearly suggests its involvement in the fast step. First order kinetics with respect to each glycols and ruthenium (III) chloride was observed. Various actvation parameters have been calculated and recorded. On the basis of the experimental findings a suitable mechanism has been proposed.

 

 

 

Indian Journal of Chemistry
Vol. 41A March  2002, pp. 550-553

 

Synthesis and characterization of palladium(II) complexes containing

N-pyridiniodithiophosphinates

 

Vimal K Jain, Leena Hemrajani & Raj K Bansal

Palladium complexes of the type [PdCl2(L)(dithio)] with zwitterionic dithio ligands have been synthesized from the reaction of [Pd2Cl2(m-Cl)2L2] with pyridiniodithiophosphinates in 1:2 molar ratio in dichloromethane at room temperature. These complexes have been characterized by elemental analysis, IR and NMR (1H and 31P) spectral data.

 

Indian Journal of Chemistry
Vol. 41A March  2002, pp. 554-559

 

Synthesis, magnetic and spectral studies of some cis-dioxomolybdenum(vi) complexes derived from N, O- and N2O2- type Schiff bases

 

R C Maurya, B Shukla, & A Pandey

 

The synthesis of six new mononuclear and binuclear dioxomolybdenum(VI) chelates of compositions, [MoO2(OH)(L)]2, where L = N- (4'-butyrylidene-3'-methyl-1'-phenyl-2'-pyrazolin-5'-one)-p-anisidine (BUMPHP-PAH, I), N- (4'-butyrylidene-3'-methyl-1'-phenyl-2'-pyrazolin-5'-one)-m-phenetidine (BUMPHP-MPH, II) or N- (4'-butyrylidene-3'-methyl-1'-phenyl-2'-pyrazolin-5'-one)-p-toluidine (BUMPHP-PTH, III), [MoO2(L)], where L = N, N'-bis-(4'-butyrylidene-3'-methyl-1'-phenyl-2'-pyrazolin-5'-one)-o-phenylenediamine (BUMPHP- OPHDH2 ,IV), [MoO2(H2O)(L)], where L = N, N'-bis(4'-butyrylidene-3'-methyl-1'-phenyl-2'-pyrazolin-5'-one)-m-phenylenediamine (BUMPHP- MPHDH2,V) and  [{MoO2(OH)}2(L)], where L = N, N'-bis(4'-butyrylidene-3'-methyl-1'-phenyl-2'-pyrazolin-5'-one)-benzidine (BUMPHP-BZH2,VI) have been reported. These chelates have been prepared by the interaction of [MoO2(acac)2] ( where acacH = acetylacetone)  with the respective  pyrazolone based Schiff base ligand in ethanol medium. The resulting chelates have been characterized on the basis of  elemental analyses, molar conductance, decomposition temperature, magnetic measurement, thermogravimetric analyses, 1H-NMR, IR and electronic spectral studies and have been found to contain cis-MO2 structure.

 

 

Indian Journal of Chemistry
Vol. 41A March  2002, pp. 560-562

 

Synthesis and characterization of ruthenium(II) complexes of different types of potential unsymmetrical hemilabile  P-O and P-S donors ligands

 

Pankaj Das, Manab Sharma, Nandini Kumari, Dilip Konwar & Dipak Kumar Dutta

Various potential bidentate hemilabile ligands with different aliphatic backbones, such as Ph2PCH2CH2COOC2H5(a), Ph2PCH(CH3)COOCH3(b), Ph2PCH2OCH3(c), Ph2PCH2CH2OC2H5(d), Ph2PCH2CH2SC2H5(e) react with [RuCl2(PPh3)3] in 3:1 molar ratio to  produce complexes of the type [RuCl2(P~X)2(PÇX)] (1a-e) [where P~X = h1- (P) coordinated; PÇX = h2- (P,X) coordinated ligand; X = O, S]. On the other hand, reaction of a ligand containing an aromatic backbone unit such as o-Ph2PC6H4COOC2H5 with [RuCl2(PPh3)3] produces a bis-chelate complex [RuCl2(PÇO)2] (2). The complexes have been characterized by elemental analysis, IR, 1H, and 31P{1H} NMR spectroscopy.

 

 

Indian Journal of Chemistry
Vol. 41A March  2002, pp. 563-564

 

 A   spectrophotometric method for the trace determination of vanadium as V (V )-5-chloro-8-hydroxy-
7-iodoquinoline in aqueous medium

 

Vanita Sharma, Monica Nijhawan & A L J Rao

A simple and rapid spectrophotometric method for the determination of vanadium (V) is developed in the presence of 5-choloro-8-hydroxy-7-iodoquinoline under acidic conditions using Triton X-100 as surfactant. Pb (II), Zn (II ),Mn (II ), Co (II), Cr (III), Hg (II), Bi (III) do not interfere when added in large amounts while Fe (III), Fe (II), Ni (II), Pd (VI), Zr (IV), Cr (II), Cu (II), Mo (VI), are tolerated in smaller concentrations. The applicability of the method has been tested by analysis of a large number of different synthetic and commercial samples. The method is highly reproducible with standard deviation of ± 0.005 and Sandell’s sensitivity 2.85x10-3 µg V cm-2. The stoichiometry of the complex has also been studied.