Indian Journal of Chemistry

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


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VOLUME 44A

NUMBER 9

SEPTEMBER 2005

 

CONTENTS

Papers

 

1751

 

Anomalous cyclic conjugation in benzenoid molecules with a small number of Kekulé structures

 

 

 

 

 

 

 

 

 

 

Ivan Gutman*, Sonja Stanković,
Radmila Kovačević, Jelena Đurđević &
Boris Furtula

 

 

 

With the example of a suitably chosen class of benzenoid systems with a small number of Kekulé structures, it has been shown that the cyclic conjugation in the rings with "fixed" bonds (measured by its energy-effect) may be unexpectedly high, contradicting the results of standard Kekulé structure-based considerations.

 

 

 

1756

 

Sol-gel processed cerium oxide and mixed cerium–titanium oxide films as passive counter electrodes for transmissive electrochromic devices

 

 

 

 

 

 

 

 

 

Amita Verma, S B Samanta, A K Bakhshi &
S A Agnihotry*

 

 

 

Thin films of CeO2 and mixed oxide CeO2-TiO2 with Ce/Ti mole ratio of one have been obtained by an alcohol-based sol-gel process. The mixed oxide film is characterized by the prevalence of amorphicity, though morphological studies have indicated the presence of CeO2 nanograins. The films prepared from an aged sol exhibit a much higher ion insertion capacity and transparency as compared to those deposited using as-prepared sol. The ion insertion capacity obtained for an 800 nm thick film of mixed oxide is of the order of 18.36 mC cm-2 at a frequency of 0.0011 Hz. Fast coloration–bleaching kinetics for WO3 in conjunction with the mixed CeO2-TiO2 film indicates its potential as a passive counter electrode in electrochromic devices.

 

 

1766

 

Theoretical study of the effect of band width on the electronic properties of copolymers of type-I and type-II staggered

 

 

 

 

 

 

 

 

 

 

 

Amit Kumar, Geetika Bhalla & A K Bakhshi*

 

 

 

The effect of band widths of both valence and conduction bands of the homopolymers (A)x, (B)x and (C)x on the electronic properties of the model copolymers (AmBn)x and (AmCn)x has been investigated on the basis of the negative factor counting method in tight binding approximation. Using model band structures of the three homopolymers, the electronic density of states of their various periodic and aperiodic copolymers have been determined. On the basis of the band alignments of the constituent homopolymers, the copolymers (AmBn)x, belong to the class of type-I while those (AmCn)x belong to the class of type-II staggered.

 

 

1772

 

Selective benzylation of benzene over alumina pillared clays

 

 

 

 

 

 

 

 

 

 

 

Manju Kurian & S Sugunan*

 

 

 

 

1782

 

A series of new generation bismuth and boron addition complexes of C60, prepared through high temperature solid state reactions

 

 

R Sahoo, D Banerjee, S K Bhattacharya &
R Debnath*

 

 

 

A series of bismuth and oxyboron addition complexes of fullerene through solid state reaction between C60 and a (zinc, bismuth) borate glass at 650-700°C under argon atmosphere has been synthesized. The bismuth ions of the glass, add directly to the C60 cage, while the borate ions, like osmate ions, add through oxygen. The composite glasses exhibit good nonlinear optical properties and enhanced electrical conductivity.

 

 

1793

 

Micellization behaviour of lithium dodecyl sulphate in aqueous solutions using conductivity, density and adiabatic compressibility measurements

 

 

 

 

 

Chanchal Das & Dilip K Hazra*

 

 

 

Temperature effects on micellar behavior of lithium dodecyl sulphate in aqueous solutions have been measured using conductometric, densitometric, and interferrometric techniques. Conductivity studies, in the range 288.15-318.15 K at 5 K intervals, shows the cmc to be temperature dependent with a shallow minimum at around 298.42 K. The ionization degree of micelles increases whereas the standard free energy of micellization decreases with increase in temperature.

 

 

1800

 

Synthesis, structure and reactivity of oxovanadium(IV) schiff base complexes

 

 

 

 

 

A P Mishra* & L R Pandey

 

 

 

Oxovanadium(IV) complexes with schiff bases, viz., N,N'-bis(2-hydroxy benzylidene)benzidine, N,N'-bis(2-hydroxy benzylidine)-p-phenylenediamine and cinnamylidene-2-aminophenol have been synthesized and characterized.

 

 

 

Notes

 

1806

 

Microwave assisted synthesis and characterization of mixed metal hydrazinecarboxylates, metal cobaltites and metal ferrites

 

 

 

B N Sivasankar

 

 

 

Metal cobaltites and ferrites have been prepared by the combustion of an aqueous mixture of metal nitrates and hydrazinium hydrazinecarboxylate in a microwave oven.

 

M(NO3)2 xH2O + 2 M¢(NO3)2 yH2O + 6N2H3COON2H5 ®

MM¢2 (N2H3COO)6 + 6(N2H4) + 6HNO3 + (x+y)H2O

 

MM¢2 (N2H3COO)6 à MM¢2O4 + 9H2O +6N2 + 6CO2

 

 

1812

 

Complexes of iron(III) with 1,2-dihydro-1,5-dimethyl-2-phenyl-4-formyl(benzhydrazide)–3H-pyrazol-3-one

 

 

 

 

 

P K Radhakrishnan* & K C Raju

 

 

 

 

 

1817

 

Transition metal carbene chemistry.
3: Nucleophilic attachment of 4-nitrophenyl acetonitrile and benzoyl nitromethane anions to Fischer carbene complexes

 

 

 

 

 

 

Mahammad Ali

 

 

 

1822

 

Anionic micellar catalysis in the redox reaction of aminoalcohols with N-bromosuccinimide in alkaline medium: A kinetic study

 

 

 

 

 

 

Shalini Pandey & Santosh K Upadhyay*

 

 

 

The kinetics of oxidation of aminoalcohols, viz., ethanolamine, diethanolamine and triethanolamine by N-bromosuccinimide has been investigated in presence of sodium lauryl sulphate in alkaline medium. A first order dependence of rate with respect to [oxidant] has been observed. The order in both the substrate and alkali decreases from unity to zero at higher [substrate] or [OH-]. The catalytic influence of anionic micelle on rate of the reaction has been studied at different temperatures.

 

 

1827

 

Kinetics and mechanism of oxidation of substituted benzyl alcohol by polymer supported oxidizing agent

 

 

 

 

 

A L Jawanjal & N P Hilage*

 

 

 

The kinetics of oxidation of substituted benzyl alcohol with polymer supported chromic acid in 1:4 dioxane has been studied.

 

 

 

1831

 

Effect of solvents and nucleophiles on the reactivity of allyl bromide—A kinetic study

 

 

 

 

 

 

 

S Ranga Reddy, P Kalyani & P Manikyamba*

 

 

The kinetics of the reaction of allyl bromide with benzoyl thiosemicarbazide has been studied in different protic and aprotic solvents. Correlation of rate constants with different solvent parameters indicates that the
non- specific solvent parameters, Y, P and nucleophilicity, B, influence the rate of nucleophilic substitution. Study of the reaction with substituted thiosemicarbazides indicates that structural effects on rate of the reaction is minimal.

 

 

1834

 

Ultrasonic measurements in solutions of electrolytes in dimethyl sulfoxide + water mixtures at different temperatures

 

 

 

 

 

Rita Mehra

 

 

 

Ultrasound speed and density of electrolytes CdCl2+ KCl have been measured in DMSO and H2O mixtures at
2 MHz from 25-45°C. Solvation number increases with increase in mole fraction of CdCl2 suggesting significantly strong interactions in the system. Acoustic impedance also increases with mole fraction of CdCl2 indicating significant interactions in the CdCl2 – KCl system in DMSO + H2O.

 

 

1838

 

Synthesis of a novel ion exchanger, ceric vanadate and its application to the separation of 90Sr-90Y pair

 

 

 

 

Samir Maji, Susanta Lahiri* & S Basu

 

 

 

A new inorganic ion exchanger, ceric vanadate (4CeO2.5V2O5.12H2O), has been synthesized and characterized. The ion exchanger is highly stable towards thermal, chemical and radiation effects and has a high ion exchange capacity for some metal ions. It has been used to separate 90Y from 90Sr-90Y equilibrium mixture with high purity 90Y being eluted out with 0.01 M EDTA solution.

 

 

Authors for correspondence are indicated by (*)

 

 

Indian Journal of Chemistry

Vol. 44A, September 2005, pp. 1751-1755


 

Anomalous cyclic conjugation in benzenoid molecules with a small number of Kekulé structures

Ivan Gutman*, Sonja Stanković, Radmila Kovačević, Jelena Đurđević & Boris Furtula

Received 16 May 2005; revised 14 June 2005

The currently used Kekulé-structure-based models for assessing the extent of cyclic conjugation in benzenoid hydrocarbons predict that there is no or very little cyclic conjugation in the rings possessing “fixed” double and single carbon-carbon bonds. With the example of a suitably chosen class of benzenoid systems with a small number of Kekulé structures, we show that the cyclic conjugation in the rings with “fixed” bonds (measured by its energy-effect) may be unexpectedly high, contradicting the results of standard Kekulé-structure-based considerations. Consequently, our study reveals that the analysis of the conjugation modes of polycyclic aromatic compounds, based solely on Kekulé structures, may sometimes be insufficient and may lead to erroneous conclusions.

Indian Journal of Chemistry

Vol. 44A, September 2005, pp. 1756-1765


 

Sol-gel processed cerium oxide and mixed cerium–titanium oxide films as passive counter electrodes for transmissive electrochromic devices

Amita Verma, S B Samanta, A K Bakhshi & S A Agnihotry*

Received 12 August 2004; revised 17 May 2005

Thin films of CeO2 and mixed oxide CeO2-TiO2 with a Ce/Ti mole ratio of one have been obtained by an alcohol based sol-gel process. The precursor materials for the latter comprises a Ce(III) salt, CeCl3.7H2O and titanium propoxide in ethanol. The mixed oxide film is characterized by the prevalence of amorphicity, though morphological studies have indicated the presence of CeO2 nanograins. Pure cerium oxide film exhibits crystalline nature with the average grain size in the nanorange. In agreement with the higher levels of Li+ ion intercalation in an amorphous film in comparison to crystalline film, a superior inserted/extracted charge in the mixed oxide film is revealed from the electrochemical investigations. The films prepared from an aged sol are observed to exhibit a much higher ion insertion capacity and transparency as compared to the films deposited using as-prepared sol. The ion insertion capacity obtained for an 800 nm thick film of mixed oxide is of the order of 18.36 mC cm-2 at a frequency of 0.0011 Hz. The presence of well-defined grains of about 89 nm dimension in the CeO2-TiO2 film has been determined by the AFM studies. The measurements on the films for electrochromic applications such as “smart windows” reveal fast coloration–bleaching kinetics for WO3 in conjunction with the mixed CeO2-TiO2 film and affirm its suitability as passive counter electrode in electrochromic devices.

IPC Code: Int. Cl.7 C04B35/01; C04B35/46; C04B35/624; H01G9/00; H01M4/48

Indian Journal of Chemistry

Vol. 44A, September 2005, pp. 1766-1771


 

Theoretical study of the effect of band width on the electronic properties of copolymers of type-I and type-II staggered

Amit Kumar, Geetika Bhalla & A K Bakhshi*

Received 13 January 2005; revised 17 June 2005

The effect of band widths of both valence and conduction bands of the homopolymers (A)x, (B)x and (C)x on the electronic properties of the model copolymers (AmBn)x and (AmCn)x has been investigated on the basis of the negative factor counting method in tight binding approximation. Using model band structures of three homopolymers (A)x, (B)x and (C)x, the electronic density of states (DOS) of their various periodic and aperiodic copolymers have been determined. On the basis of the band alignments of the constituent homopolymers, the copolymers (AmBn)x, belong to the class of type-I while (AmCn)x belong to the class of type-II staggered. For both Type-I and Type-II staggered copolymers, three model systems differing in the band widths of the valence and conduction bands have been studied. The trends in the electronic structures and conduction properties of these copolymers as a function of band width are reported.

Indian Journal of Chemistry

Vol. 44A, September 2005, pp. 1772-1781


 

Selective benzylation of benzene over alumina pillared clays

Manju Kurian & S Sugunan*

Received 13 December 2004; revised 16 June 2005

Aluminium pillared clays prepared by partial hydrolysis method has been subjected to room temperature exchange with transition metals of the first series. The resulting materials exhibit a fine porous network of exceptional stability as characterized by XRD, FTIR and NMR spectroscopy. EDX and surface area measurements indicate the presence of exchanged metals attached to the pillars. Acidity of the pillared clay benefits from the insertion of transition metals. Benzylation of benzene occurs efficiently over these catalysts with 100% monoalkylated product selectivity. An extensive study of the reaction variables points towards a carbocation mechanism for the reaction. The reaction depends to a large extent on the number and availability of the Lewis acid sites.

IPC Code: Int. Cl.7 B01J21/16

 

Indian Journal of Chemistry

Vol. 44A, September 2005, pp. 1782-1792


 

A series of new generation bismuth and boron addition complexes of C60, prepared through high temperature solid state reactions

R Sahoo, D Banerjee, S K Bhattacharya & R Debnath*

Received 5 January 2005; revised 29 June 2005

Synthesis of a series of bismuth and oxyboron addition complexes of fullerene through solid-state reaction between C60 and a (zinc, bismuth) borate glass at 650-700°C under argon atmosphere is reported here. Depending on the reaction conditions, different complexes are formed in different proportions which remain encased in the matrix of the glass imparting different colours to the composite. By controlling the reaction conditions, two composite glasses, one of green colour and the other of red colour have been obtained. Relatively better stability of these complexes enabled us to extract at least, the relatively low molecular weight species of these complexes of the composites by eluting the latter with toluene. The complexes are characterized by UV-Vis-NIR absorption, mass and IR studies. It is observed that the bismuth ions of the glass add directly to the C60 cage, while borate ions, like osmate ions, add through oxygen. The composite glasses exhibit good non-linear optical properties and enhanced electrical conductivity showing a possibility of their use in different device applications.

IPC Code: Int. Cl.7 C07F5/00; C07F9/94

 

Indian Journal of Chemistry

Vol. 44A, September 2005, pp. 1793-1799


 

Micellization behaviour of lithium dodecyl sulphate in aqueous solutions using conductivity, density and adiabatic compressibility measurements

Chanchal Das & Dilip K Hazra*

Received 22 March 2005; revised 31 May 2005

Temperature effects on micellar behaviour of lithium dodecyl sulphate in aqueous solutions have been measured using conductometric, densiometric, and interferrometric techniques. All these methods yield almost identical critical micelle concentration (cmc) for the surfactant system. Conductivity studies, in the range 288.15-318.15 K at 5 K intervals, show a shallow minimum of the cmc values at around 298.42 K. The ionization degree of micelles (a), has been found to increase whereas the standard free energy of micellization (DGom) decreases upon increase in temperature. Variation in standard enthalpy upon aggregation has been calculated by using Gibbs-Helmholtz equation. From density measurements carried out at 288.15, 298.15 and 308.15 K, the changes of the apparent molar volume upon micellization of the surfactant have been calculated. The apparent adiabatic compressibilities of the surfactant solutions have also been calculated using density and ultrasound velocity measurements and provide information on the solution behaviour of the surfactant in aqueous solution.

IPC Code: Int. Cl.7  G01N

 

Indian Journal of Chemistry

Vol. 44A, September 2005, pp. 1800-1805

 

Synthesis, structure and reactivity of oxovanadium(IV) schiff base complexes

A P Mishra* & L R Pandey

Received 10 November 2004; revised 16 June 2005

Oxovanadium(IV) complexes with schiff bases, viz., N,N'-bis(2-hydroxy benzylidene)benzidine (HBB), N,N'-bis(2-hydroxy benzylidine)-p-phenylenediamine (HBP) and cinnamylidene-2-aminophenol (CAPh) have been synthesized and characterized by elemental analysis, molar conductance, electronic spectra, FT-IR, 1H-NMR, ESR, FAB mass, thermal and magnetic susceptibility measurements. FAB mass and thermal data show degradation pattern of the complexes. Square pyramidal geometry has been proposed for the complexes. The reactivity and substitution behaviour of the synthesized complexes have also been studied. Solid-state A.C. electrical conductivity studies reflect semiconducting nature of the complexes. The crystal system, lattice parameters, unit cell volume and number of molecules in unit cell of [VO(HBB)(H2O)2] complex have been determined by XRD, suggesting that the [VO(HBB)(H2O)2] complex crystallizes as tetragonal crystal system.

IPC Code: Int. Cl.7 C07F9/00; C07C251/02

 

Indian Journal of Chemistry

Vol. 44A, September 2005, pp. 1806-1811


 

Microwave assisted synthesis and characterization of mixed metal hydrazinecarboxylates, metal cobaltites and metal ferrites

B N Sivasankar

Received 24 May 2004; revised 5 July 2005

Metal cobaltites and ferrites have been prepared by the combustion of an aqueous mixture of metal nitrates and hydrazinium hydrazinecarboxylate in a microwave oven. The concentrated solution formed just before decomposition to the respective cobaltites or ferrites is removed and allowed to crystallize at room temperature. Composition of the complexes obtained from the above concentrated solutions has been found to be M1/3Co2/3(N2H3COO)2 or M1/3Fe2/3(N2H3COO)2 where M= Mg, Mn, Fe, Co, Ni or Zn. The solid products obtained by the decomposition of the combustion mixture and the complexes isolated from the concentrated solutions have been characterized by chemical analyses, infrared spectra and X-ray powder diffraction studies. Thermal degradation of the complexes has also been recorded and the final residues have been found to be the respective metal cobaltites or metal ferrites.

IPC Code: Int. Cl.7 C01G49/00; C01G51/00; C04B35/26; C07C241/02; H05B6/64

Indian Journal of Chemistry

Vol. 44A, September 2005, pp. 1812-1816


 

Complexes of  iron(III) with 1,2-dihydro-1,5-dimethyl-2-phenyl-4-formyl(benzhydrazide)–3H-pyrazol-3-one

P K Radhakrishnan* & K C Raju

Received 7 January 2005; revised 5 July 2005

Iron(III) complexes of the schiff base, 1,2-dihydro-1,5-dimethyl -2- phenyl -4- formyl(benzhydrazide)-3H-pyrazol-3-one, [Fe(DPFBP)2X]X2, (where X=ClO4, or NO3) and [Fe(DPFBP)2X2]x (X=SCN, Cl or Br) have been synthesized and characterized by elemental analyses, electrical conductance in non-aqueous solvents, infrared, and electronic spectra as well as magnetic susceptibility measurements. In these complexes, DPFBP acts as a neutral bidentate ligand coordinating through the azomethine nitrogen and the carbonyl oxygen of the pyrazolone ring.  The molar conductance of the complexes in DMF, methanol and nitrobenzene are in the range suggested for 1:2 electrolytes for perchlorate and nitrate complexes while the thiocyanate, chloride and bromide complexes behave as 1:1 electrolytes. The electronic spectra of the complexes exhibit a band in the region 19,230-20,080 cm-1 due to 6A1g®4T1g consistent with octahedral Fe(III) complexes. The molar magnetic moment of the complexes varies in the range 5.61-6.05 B.M., indicative of octahedral geometry.

IPC Code: Int. Cl.7 C07F15/00

Indian Journal of Chemistry

Vol. 44A, September 2005, pp. 1817-1821


 

Transition metal carbene chemistry. 3: Nucleophilic attachment of 4-nitrophenyl acetonitrile and benzoyl nitromethane anions to Fischer carbene complexes

 

Mahammad Ali

Received 16 March 2005; revised 25 June 2005

Rate constants for the nucleophilic attachment of 4-NO2-PhCH(CN)- and PhCOCHNO2- to Fischer carbene complexes of the type (CO)5M=C(SMe)C6H5 with M = Cr and W in 50% MeCN-50% water (v/v) at 25°C are reported. The acetonitrile anions PhCH(CN)- show much higher reactivity towards these carbene complexes than OH, primary aliphatic amines (e.g., n-butylamine) or secondary alicyclic amines (e.g., piperidine) but are less reactive than thiolate ions (e.g., HOCH2CH2S) and CH(CN)2-. The carbanion PhCOCHNO2- is more reactive than OH- but less reactive than the above-mentioned ions. The reactivity of carbanions towards a particular carbene complex follows the order: CH(CN)2-> 4-NO2-PhCH(CN)- > PhCOCHNO2- for both the carbene complexes. The possible explanation for it comes from the delocalization of negative charge on the carbanion which follows the reverse order. The higher reactivity of 1-W over 1-Cr for all the carbanions fits a pattern observed previously and arises mainly due to lowering of intrinsic barrier of the tungsten carbene complex than corresponding chromium one.

IPC Code: Int.Cl.7 C07F11/00

Indian Journal of Chemistry

Vol. 44A, September 2005, pp. 1822-1826


 

Anionic micellar catalysis in the redox reaction of aminoalcohols with N-bromosuccinimide in alkaline medium: A kinetic study

 

Shalini Pandey & Santosh K Upadhyay*

Received 30 September 2004; revised 31 May 2005

The kinetics of oxidation of aminoalcohols, viz., ethanolamine, diethanolamine and triethanolamine by N-bromosuccinimide has been investigated in presence of anionic surfactant, viz., sodium lauryl sulphate in alkaline medium. A first order dependence of rate with respect to [oxidant] has been observed. The order in both the substrate and alkali is found to decrease from unity to zero at higher [substrate] or [OH-]. The catalytic influence of anionic micelle on rate of the reaction has been studied at different temperatures.

IPC Code: Int. Cl.7 C07B33/00

 

Indian Journal of Chemistry

Vol. 44A, September 2005, pp. 1827-1830


 

Kinetics and mechanism of oxidation of substituted benzyl alcohol by polymer supported oxidizing agent

A L Jawanjal & N P Hilage*

Received 20 August 2004; revised 19 July 2005


The kinetics of oxidation of monosubstituted benzyl alcohol with polymer supported chromic acid in 1:4 dioxane has been studied. The reaction is found to be of zero order each in [alcohol] and [oxidant]. The effect of substituent on the rate of oxidation and the thermodynamic parameters are evaluated. The reaction products have been isolated and characterised by their derivatives. A probable mechanism of oxidation is proposed.

IPC Code: Int. Cl.7 C07B33/00

Indian Journal of Chemistry

Vol. 44A, September 2005, pp. 1831-1833


 

Effect of solvents and nucleophiles on the reactivity of allyl bromideA kinetic study

 

S Ranga Reddy, P Kalyani & P Manikyamba*

Received 18 November 2004; revised 31 May 2005

The kinetics of the reaction of allyl bromide with benzoyl thiosemicarbazide has been studied in different protic and aprotic solvents. Correlation of rate constants with different solvent parameters applying linear multiple regression analysis indicates that the non-specific solvent parameters Y, P and nucleophilicity, B, influence the rate of nucleophilic substitution. Using these solvent parameters, the linear solvation energy relationship is derived. Study of the reaction with substituted thiosemicarbazides indicates that structural effects on rate of the reaction are minimal.

 

Indian Journal of Chemistry

Vol. 44A, September 2005, pp. 1834-1837


 

Ultrasonic measurements in solutions of electrolytes in dimethyl sulfoxide + water mixtures at different temperatures

Rita Mehra

Received 29 June 2004; revised 27 July 2005

Ultrasound speed and density of electrolytes CdCl2+ KCl have been measured in DMSO and H2O mixtures at 2 MHz from 25 to 45oC. Various derived parameters such as acoustic impedance, adiabatic compressibility and solvation number have been calculated. The results have been discussed in terms of the nature of electrolyte and solvent mixtures. Solvation number throws light on the solute-solute and solute-solvent interactions.

IPC Code: Int.Cl.7 B01J19/10

Indian Journal of Chemistry

Vol. 44A, September 2005, pp. 1838-1840


 

Synthesis of a novel ion exchanger, ceric vanadate and its application to the separation of 90Sr-90Y pair

Samir Maji, Susanta Lahiri * & S Basu

Received 17 January 2005; revised 31 May 2005

A new inorganic ion exchanger, ceric vanadate, has been synthesized and characterized. The ion exchanger is highly stable towards thermal, chemical and radiation effects. The probable formula of the exchanger is 4CeO2.5V2O5.12H2O. It has high ion exchange capacity for some metal ions. The newly synthesized ion exchanger has been used to separate 90Y from 90Sr-90Y equilibrium mixture. High purity 90Y has been eluted out with 0.01 M EDTA solution.

IPC Code: Int. Cl.7 B01J39/02