Indian Journal of Chemistry
Sect. A: Inorganic, Bio-inorganic, Physical, Theoretical & Analytical
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VOLUME 45A

NUMBER 2

February 2006

CONTENTS

Papers

 

347

 

On π-electron excess of rings of benzenoid molecules

 

 

 

 

 

 

 

 

 

Ivan Gutman*, Andrej Vodopivec,
Slavko Radenković & Boris Furtula

 

 

 

A π-electron-content-like quantity has been computed from the Hosoya bond orders and its close relation with the
π-electron excess has been established. The concept of
π-electron excess, is now seen to be the difference between the π-electron content of a ring calculated on the basis of perfect matching, and the analogous π-electron-like quantity, obtained by considering all matchings of the underlying molecular graph.

 

 

352

 

Electronic density of states (DOS) and conduction properties of Type-II staggered copolymers of thiophene based donor-acceptor polymers

 

 

 

 

 

 

 

Amit Kumar & A K Bakhshi*

 

 

 

The electronic structures and conduction properties of periodic and aperiodic Type-II staggered copolymers (AmBn)x, (BmCn)x and (AmCn)x of three thiophene based donor acceptor polymers, PHTH (A)x, PFTH (B)x and PCNTH (C)x have been investigated A higher percentage of low band gap component in a copolymer chain improves its n-dopantphilicity while a higher percentage of large band gap component, besides improving its p-dopantphilicity makes it a better intrinsic conductor of electricity.

 


 


358

 

Role of heterogeneous reactions in generating chaos and noise in oscillatory chemical reactions

 

 

 

 

 

 

 

 

R P Rastogi*, Ishwar Das, P K Srivastava,
Prem Chand & Sharwan Kumar

 

 

 

Studies on chaos and noise on the oscillatory reactions, thiophenol + BrO3- + H2SO4, fructose + BrO3- + H2SO4 + Ce4+, and iodate + arsenite, have been undertaken. Aperiodic oscillations have been observed in these systems. Analysis of phase plane plots yields complex attractors, which are quite different from strange attractor indicating the occurrence of random noise. Power spectra also indicate chaos with a broad band not necessarily the deterministic chaos.

 

 

365

 

Synthesis and crystal structure of the one-dimensional infinite chain bismuth() complexes{Bi(NO3)[S2CN(C4H9)2](CH3OH)} and {Bi(NCS)[S2CN(C2H5)2]}

 

 

 

 

 

 

 

 

 

Han Dong Yin*, Chuan Hua Wang & Qiu Ju Xing

 

 

 

 

 

 

 

370

 


Synthesis and studies of ionic chelates of hafnocene with guanine

 

 

 

 

 

 

 


Ekta Malhotra, N K Kaushik* & H S Malhotra

 

 

 

 

 

 

377

 

Synthesis, characterization, antibacterial and anthelmentic activities of copper(II) complexes with benzofuran Schiff bases

 

 

 

 

 

 

K Ramakrishna Reddy, K Madhusudan Reddy &
K N Mahendra*

 

 

 

Copper(II)chloride reacts with Schiff bases derived from benzaldehydes/acetophenone with 3-amino-2-benzofuran carboxamide/ethyl-3-amino-2-benzofuran carboxylate to yield polymeric complexes of the type, CuLCl2 (L = Schiff base). The ligands act as bidentate, with azomethane nitrogen and carbonyl oxygen atom as donor sites. An octahedral geometry is proposed for the Cu(II) complexes.


 


382

 

Use of chiral mixed ligand Co(II) complexes as catalysts in decomposition of hydrogen peroxide

 

 

 

 

 

 

 

 

 

V S Shivankar & N V Thakkar*

 

 

 

 

388

 

Kinetics and mechanism of oxidation of arsenic(III) by quinolinium dichromate(QDC) in aqueous perchloric acid

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

S A Chimatadar, M S Salunke &
S T Nandibewoor*

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Notes

 

394

 

Reactivity of triphenyltin(IV) O,O'-dialkyl/alkylene dithiophosphates with Lewis bases

 

 

 

S K Srivastava*, R S Yadav, A Gaur & N Dubey

 

 

 

 

 

398

 

Kinetics and mechanism of oxidation of arsenous acid by Waugh-type enneamolybdomanganate(IV)

 

 

 

 

 

 

B D Bhosale & G S Gokavi*

 

 

 

 


 


402

 

Differential pulse polarographic determination of tetramethylthiuram disulphide

 

 

 

 

 

B C Verma*, Satish Kumar, Chetan Chauhan &
D K Sharma

 

 

 

A differential pulse polarographic method for the determination of tetramethylthiuram disulphide based on its reaction with copper(I) perchlorate in acetonitrile has been developed. The cyclic voltammogram shows a well-defined, diffusion-controlled peak at –120 mV showing five times more sensitivity than the one obtained due to the analyte alone.

 

406

 

Solvent extraction separation of thorium(IV)from nitric acid with Cyanex 272

 

 

 

 

 

 

Manjusha Karve*, Smruti Belwalkar &
Reeta Rajgor

 

 

 

Thorium(IV) has been quantitatively extracted from 1´10-3 M nitric acid with 1´10-3 M Cyanex 272 in xylene, stripped from the organic phase with 4 M hydrochloric acid and determined spectrophotometrically as its complex with Arsenazo(III) at 655 nm. The developed method has been applied for the separation of thorium(IV) from chromium(VI), vanadium(V), hafnium(IV), zirconium(IV), titanium(IV), iron(III), cobalt(II), calcium(II) and some rare earth elements. The applicability of the method has been checked for separation of thorium(IV) from associated elements in the synthetic mixtures and monazite sand.

 

 

409

 

Atomic absorption spectrometric determination of copper after adsorption of its sodiumdiethyl-dithiocarbamate complex on a new polymeric adsorbent

 

 

 

 

 

 

Atamjyot, Preeti Jain & B K Puri*

 

 

 

An atomic absorption spectrometric method for the determination of trace amounts of copper in various synthetic samples after adsorption of its sodiumdiethyldithiocarbamate complex on a new polymeric adsorbent has been developed. The copper complex is quantitatively adsorbed on the polymeric adsorbent in the pH range of 2.9-9.0. After filtration, the copper complex is eluted with 10 mL of dimethyl formamide and the metal is determined by atomic absorption spectroscopy. Beer’s law is obeyed in the concentration range 0.15-2.0 ppm of copper in the final DMF solution with a correlation factor of 0.9989.

 

 

Authors for correspondence are indicated by (*)

 

 

Indian Journal of Chemistry

Vol. 45A, February 2006, pp. 347-351

 

On π-electron excess of rings of benzenoid molecules

Ivan Gutman*, Andrej Vodopivec, Slavko Radenković & Boris Furtula

Received 15 November 2005; accepted 26 December 2005

In a previous paper [Gutman I, Indian J Chem 43A (2004) 1615], the concept of π-electron excess of rings of benzenoid hydrocarbons has been introduced, aimed at amending the π-electron contents of rings computed on the basis of Pauling bond orders. We now show how a π-electron-content-like quantity can be computed from the Hosoya bond orders and establish its close relation with the π-electron excess.

Indian Journal of Chemistry

Vol. 45A, February 2006, pp. 352-357

 

Electronic density of states and conduction properties of Type-II staggered
copolymers of thiophene based donor-acceptor polymers

Amit Kumar & A K Bakhshi*

Received 31 May 2005; revised 21 October 2005

Using the ab initio band structure results of three thiophene based donor-acceptor polymers, PHTH (A)x, PFTH (B)x and PCNTH (C)x, the electronic density of states of their various periodic and aperiodic copolymers (AmBn)x, (AmCn)x and (BmCn)x belonging to the class of Type-II staggered have been determined in tight binding approximation. The unit cell of these donor acceptor polymers consists of bicyclopentadithiophene unit bridged by an electron accepting group >C=CH2 in PHTH (A)x, >C=CF2 in PFTH (B)x and >C=C(CN)2 in PCNTH (C)x. The trends obtained in the electronic structures and conduction properties of these copolymers as a function of block size, composition and the arrangement of blocks in the copolymer chains are discussed. The results are important guidelines for designing novel polymers with desired conduction properties.

Indian Journal of Chemistry

Vol. 45A, February 2006, pp. 358-364

Role of heterogeneous reactions in generating chaos and noise in oscillatory chemical reactions

 

R P Rastogi*, Ishwar Das, P K Srivastava, Prem Chand & Sharwan Kumar

Received 23 March 2005; accepted 18 November 2005

In view of the importance of noise in physiology, information processing and finance, studies on chaos and noise have been undertaken. Detailed studies on the following oscillatory reactions have been undertaken: (i) thiophenol + BrO3- + H2SO4, (ii) fructose + BrO3- + H2SO4 + Ce4+, and (iii) iodate + arsenite, which can serve as a model system for this purpose. Aperiodic oscillations have been observed in these systems. Analysis of phase plane plots yields complex attractors, which are quite different from strange attractor indicating the occurrence of random noise. Power spectra also indicate chaos with a broad band not necessarily the deterministic chaos. For the reactions (i) and (iii), a mechanism has been proposed involving precipitation of C6-H5-S-C6H5 and iodine, respectively; while in case of reaction (ii), gaseous evolution of Br2 has been invoked. Experimental studies on sedimentation of C6H5-S-C6H5 and Br2 evolution confirm that such heterogeneous reactions play an important role in generating noise in oscillations.

 

 

Indian Journal of Chemistry

Vol. 45A, February 2006, pp. 365-369

 

Synthesis and crystal structure of the one-dimensional infinite chain bismuth(III) complexes{Bi(NO3)[S2CN(C4H9)2](CH3OH)} and {Bi(NCS)[S2CN(C2H5)2]}

Han Dong Yin*, Chuan Hua Wang & Qiu Ju Xing

Received 5 April 2004; accepted 20 November 2005

Synthesis of two novel bismuth(III) complexes with dithiocarbamate, {Bi(NO3)[S2CN(C4H9)2](CH3OH) (1) and {Bi(NCS)[S2CN(C2H5)2] (2) and determination of their crystal structures by X-ray single crystal diffraction are reported here. Crystal 1 belongs to triclinic with space group Pī, a=0.9563(3) nm, b=1.0333(4) nm, c=3.0599(11) nm, α=90.000(6)°,, β=90.000(7)°,, γ=90.771(7)°,, Z=4, V=3.0235(19) nm-3, Dc=1.564 g/m3, μ=6.133 mm-1, F(000)= 1416, R1=0.0593, and wR2 =0.0864. Crystal 2 belongs to monoclinic with space group P2(1)/n, a=1.6142(3) nm, b=0.65713(14) nm, c=1.8683(4) nm, β=111.098(4)°,, Z=4, V=1.8490(7) nm-3, Dc=2.025 g/m3, μ=10.094 mm-1, F(000)= 1080, R1=0.0383, and wR2 =0.0571. In complex 1, the bismuth atoms exhibit seven-coordination in distorted pentagonal bipyramidal geometry by bridging nitrate O atoms resulting in one-dimensional infinite chain structure. In complex 2, each bismuth atom adopts a distorted pentagonal bipyramidal geometry and the bridging thiocyanate groups link the Bi atoms to form one-dimensional chain polymer.

IPC Code: Int. Cl.8 C07F9/94; C07D477/20

Indian Journal of Chemistry

Vol. 45A, February 2006, pp. 370-376


Synthesis and studies of ionic chelates of hafnocene with guanine

 


Ekta Malhotra, N K Kaushik* & H S Malhotra

Received 14 January 2005; revised 5 November 2005

Ionic chelates of hafnocene with guanine (I) of the type [(h5–C5H5)2HfL]+X- (II) [X = CuCl3, ZnCl3, CdCl3, HgCl3, C6H5NHNHCS2; HL = guanine] have been synthesized. Spectral studies (IR, UV, 1H NMR and 13C NMR) indicate that the guanine moiety acts as a bidentate group, binding to the hafnium(IV) ion through carbonyl oxygen at C(6) and deprotonation of N(7). Conductance measurements reveal that the compounds are 1:1 electrolytes. Fluorescence studies have been carried out for the complex containing mercury in the anionic moiety and relevant photochemical parameters have been elucidated. The thermal behaviour of the complexes has been studied by thermogravimetric and differential thermal analytical techniques. Thermodynamic parameters of the thermal decomposition process have been computed by the Coats-Redfern method and their variations have been correlated with some structural parameters of the complexes. The ligands, as well as their hafnium(IV) complexes, exhibit appreciable antibacterial and antifungal activity against E.coli, P.aeruginosa and Z.mobilis bacterial strains, and versus A.awamori and A.niger fungal strains, respectively.

IPC Code: Int.Cl8 C07D473/00; C07F1/08; C07F3/06; C07F3/08; C07F3/10

Indian Journal of Chemistry

Vol. 45A, February 2006, pp. 377-381

 

Synthesis, characterization, antibacterial and anthelmentic activities of copper(II) complexes with benzofuran Schiff bases

 

K Ramakrishna Reddy, K Madhusudan Reddy & K N Mahendra*

Received 8 July 2005; accepted 7 December 2005

Copper(II)chloride reacts with Schiff bases derived from benzaldehydes/acetophenone with 3-amino-2-benzofuran carboxamide/ethyl-3-amino-2-benzofuran carboxylate to yield polymeric complexes of general composition CuLCl2 (L = Schiff base). The authenticity of the ligands and their complexes has been established by micro analysis, magnetic susceptibility, IR, electronic, ESR spectral studies and electrical conductance measurements. The ligands act as bidentate, with azomethane nitrogen and carbonyl oxygen atom as donor sites. It is proposed that Cu(II) complexes are polymeric with octahedral geometries. All the ligands and their metal complexes have been screened for antibacterial activity against two bacteria, viz. S.aureus and E.coli. The complexes of ligands 1b, 1f, 1g and 1h show promising results against S.aureus. Anthelmentic activity of the ligands and the complexes has been tested on earthworms. The activity is enhanced significantly on complexation.

IPC Code: Int.Cl.8 C07C251/02; C07F1/08; C07D307/00

Indian Journal of Chemistry

Vol. 45A, February 2006, pp. 382-387

Use of chiral mixed ligand Co(II) complexes as catalysts in decomposition of hydrogen peroxide

V S Shivankar & N V Thakkar*

Received 7 March 2005; revised 30 December 2005

The decomposition of hydrogen peroxide in presence of some chiral mixed ligand cobalt(II) complexes as heterogeneous and heterogenized catalysts has been investigated by measuring the evolution of oxygen at different time intervals in the temperature range 35-60°C. The catalytic activity is enhanced in presence of complexes adsorbed on alumina. An increase in the amount of catalyst and pH increase the rate of the reaction. The variation of [H2O2] at a constant pH shows that the values of k are nearly constant irrespective of [H2O2]. The effect of steric hindrance due to secondary ligand on the kinetics of decomposition of hydrogen peroxide has also been studied. Various thermodynamic parameters have been calculated. The probable reaction mechanisms have been suggested in which an intermediate surface complex is thought to be responsible for the enhancement of the decomposition of hydrogen peroxide.

IPC Code: Int Cl.8 B01J23/75

 

Indian Journal of Chemistry

Vol. 45A, February 2006, pp. 388-393

Kinetics and mechanism of oxidation of arsenic(III) by quinolinium dichromate(QDC) in aqueous perchloric acid

 

S A Chimatadar, M S Salunke & S T Nandibewoor*

Received 29 September 2005; accepted 15 December 2005

The kinetics of oxidation of arsenic(III) by quinolinium dichromate(QDC) has been investigated spectrophotometrically over a wide range of arsenic(III) concentrations in aqueous perchloric acid medium and at a constant ionic strength. As the arsenic(III) concentration varies, from lower concentration region to higher one, the order with respect to [arsenic(III)] changes from first to zero order. In all the regions of the [arsenic(III)], the reaction is first order in [oxidant] and less than unit order in [acid]. Increase in [perchloric acid] accelerates the reaction rate. The added products, chromium(III) and arsenic(V) do not significantly affect the reaction rate. A suitable mechanism is proposed and the involved reaction constants have been evaluated. Activation parameters have also been calculated.

IPC Code: Int.Cl.8 C07B33/00

Indian Journal of Chemistry

Vol. 45A, February 2006, pp. 394-397

Reactivity of triphenyltin(IV) O,O'-dialkyl/alkylene dithiophosphates with Lewis bases

S K Srivastava*, R S Yadav, A Gaur & N Dubey

Received 6 April 2004; accepted 30 November 2005

The interactions of triphenyltin(IV) O,O'-dialkyl/alkylene dithiophosphates, [(C6H5)3SnS(S)P(OR)2] and [(C6H5)3SnS(S)POGO][R=-CH(CH3)2,-CH2CH2OCH3;G=-CH2C(CH3)2CH2-,-CH2C(CH3)2CHCH(CH3)2] with various S-, O- and N- donor Lewis bases yield several new molecular adducts. On the basis of elemental analysis and spectral (IR, 1H and 31P NMR) data, the presence of five- and six-coordination of Sn atom in case of unidentate and bidentate Lewis bases, respectively is concluded.

IPC Code: Int. Cl.8 C07F7/22

 

Indian Journal of Chemistry

Vol. 45A, February 2006, pp. 398-401

Kinetics and mechanism of oxidation of
arsenous acid by Waugh-type enneamolybdomanganate(IV)

B D Bhosale & G S Gokavi*

Received 28 July 2005; accepted 14 December 2005

The reaction between As(III) and Waugh-type enneamolybdomanganate(IV) has been studied in perchloric acid medium. The reaction follows a second order kinetics with an order of unity each on both the reactants and proceeds with a complimentary two-electron outer-sphere path. The reaction is accelerated by [H+] ions due to protonation equilibria of the oxidant. The first two protonation constants of the enneamolybdomanganate(IV) anion have been determined by pH metric titration and found to be 2.0 ´ 103 and 316 dm3 mol-1. The product of reaction, enneamolybdomanganous(II) has been synthesized to study the effect of the added product. Both ammonium salts of enneamolybdomanganate(IV) and enneamolybdomanganous(II) have been characterized by FTIR and AAS. The reaction is unaffected by change in ionic strength and the free radical test is negative which suggests direct two-electron transfer from As(III) to oxidant. Di-protonated form of enneamolybdomanganate(IV) has been found to be active oxidant species. The solvent polarity and the thermodynamic parameters suggest the outer sphere mechanism.

IPC Code: Int. Cl.8 C07B33/00

 

Indian Journal of Chemistry

Vol. 45A, February 2006, pp. 402-405

Differential pulse polarographic determination of tetramethylthiuram disulphide

 

B C Verma*, Satish Kumar, Chetan Chauhan & D K Sharma

Received 1 June 2005; accepted 16 December 2005

A differential pulse polarographic method for the determination of tetramethylthiuram disulphide (TMTD) by making use of its reaction with copper(I) perchlorate in acetonitrile has been developed. TMTD reacts with copper(I) perchlorate (1:1 molar ratio) and exhibits a well-defined, diffusion-controlled peak at –120 mV showing five times more sensitivity than the one obtained due to TMTD alone. The linear relationship between concentration of TMTD and current intensity of peak at –120 mV can be successfully adapted to the analysis of some fungicide and rubber accelerator formulations based on TMTD.

IPC Code: Int.Cl.8 G01R

Indian Journal of Chemistry

Vol. 45A, February 2006, pp. 406-408

Solvent extraction separation of thorium(IV) from nitric acid with Cyanex 272

Manjusha Karve*, Smruti Belwalkar & Reeta Rajgor

Received 8 July 2005; accepted 8 January 2006

Thorium(IV) has been quantitatively extracted from 1´10-3 M nitric acid with 1´10-3 M Cyanex 272 in xylene. It has been stripped from the organic phase with 4 M hydrochloric acid and determined spectrophotometrically as its complex with Arsenazo(III) at 655 nm. The method developed has been applied for the separation of thorium(IV) from chromium(VI), vanadium(V), hafnium(IV), zirconium(IV), titanium(IV), iron(III), cobalt(II), calcium(II) and some rare earth elements. The applicability of the method has been checked for separation of thorium(IV) from associated elements in the synthetic mixtures and monazite sand. The method is simple, rapid and selective for thorium(IV) with a relative standard deviation of 0.27 %.

IPC Code: Int. Cl.8 G01N

 

Indian Journal of Chemistry

Vol. 45A, February 2006, pp. 409-411

Atomic absorption spectrometric
determination of copper after adsorption of its sodiumdiethyldithiocarbamate complex on a new polymeric adsorbent

Atamjyot, Preeti Jain & B K Puri*

Received 30 August 2005; accepted 26 November 2005

An atomic absorption spectrometric method for the determination of trace amounts of copper in various synthetic samples after adsorption of its sodiumdiethyldithiocarbamate complex on a new polymeric adsorbent has been developed. The copper complex is quantitatively adsorbed on the polymeric adsorbent in the pH range of 2.9-9.0. After filtration, the copper complex is eluted with 10 mL of dimethyl formamide and the metal is determined by atomic absorption spectroscopy. Beer’s law is obeyed in the concentration range 0.15-2.0 ppm of copper in the final DMF solution with a correlation factor of 0.9989. Ten replicates of 2 ppm of Cu give a mean absorbance of 0.209 with a relative standard deviation of 1.6%. Various experimental conditions such as effect of pH on complexation/adsorption/retention, volume of buffer solution, amount of reagent, amount of adsorbent, standing time, flow rate, volume of aqueous phase, choice of organic solvent have been optimized.

IPC Code: Int. Cl.8 B01D15/00; G01J3/42