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Indian Journal of Chemistry

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

 

 

 

VOLUME 42A

NUMBER 8

AUGUST 2003

 

CONTENTS

Advances in Contemporary Research

 

17971

 

Tailored ruthenium polypyridyl complexes as molecular electronic materials

 

 

 

 

 

 

 

L Mishra*, A K Yadaw & G Govil

 

 

 

Ruthenium polypyridyl complexes tailored for molecular electronic properties are reviewed. The use of these newly synthesized materials in the construction of molecular wires, molecular rods, luminescence switches as well as in sensors are explored.

Papers

 

1815

 

Electronic structure of single stranded DNA base stacks

 

 

Shyam Kishore & A K Bakhshi*

 

 

 

The electronic density of states (DOS) curves of single stranded periodic and aperiodic DNA base stacks have been obtained by the simple negative factor counting method. The large bandgap values rule out the possibility of intrinsic conduction in them

 

1822

 

On the electronic structures and conduction properties of quasi-one-dimensional model compositional superlattices of type II-staggered

 

 

Parul Bhargava & A K Bakhshi*

 

 

 

The electronic spectra of three different quasi-one-dimensional model compositional superlattices (copolymers) (AmBn)x belonging to the class of type-II staggered have been calculated and the trends in the structure and conduction properties discussed.

 1827

 Photocyclisation of phenylbenzoquinone : A time resolved photoacoustic calorimetric and flash photolytic study

 

 

 

 

Nitin Chattopadhyay*, Carlos Serpa,  Luis G Arnaut & Sebastião J Formosinho

 

 

 

Energetics of the formation of the intermediate during the photocyclisation of phenylbenzoquinone to
2-hydroxydibenzofuran in methanol solvent is studied by employing the time-resolved photoacoustic calorimetric technique. These results and semi-empirical (AM1 and PM3) calculations suggest that the intermediate is a biradical.

 

1833

 

La(1-x)AxMn(1-y)ByO3 supported on honeycomb substrate — Characterization and application for catalytic converter

 

 

R B Biniwale*, M A Bawase, N K Labhsetwar & R Kumar

 

 

 

La0.7Sr0.3Mn0.95Pt0.05O3 supported on alumina washcoated honeycomb substrate is synthesized and characterized. The possible use of supported perovskite for automobile exhaust treatment is discussed.

 1840

 Influence of sulphate content on the physico-chemical properties and catalytic activity of some sulphated zirconia systems

 

 

Suja Haridas, C S Deepa, K Sreeranjani &  S Sugunan*

 

 

The effect of sulphate content on the physico-chemical properties and catalytic activity of sulphated zirconia and iron-promoted sulphated zirconia systems is studied. The amount of sulphate incorporated influences the surface area, crystal structure and acid strength distribution.

 

1850

 

A study of the ruthenium(III)-catalysed oxidation of L-phenylalanine by heptavalent manganese — A kinetic and mechanistic approach

 

 

S A Chimatadar, A K Kini &  S T Nandibewoor*

 

 

 

The kinetics of ruthenium(III)-catalysed oxidation of
L-phenylalanine by alkaline permanganate has been studied using a rapid kinetic accessory. The reaction is first order each in [oxidant] and [catalyst] with an apparent less than unit order each in [substrate] and [alkali].

 1856

 Monochelates and bischelates of nickel(II) with bis-benzimidazolyl derivatives

  

 

 

 Shivakumaraiah & N M Nanje Gowda

 

 

The reaction of the hydrated halides/perchlorate of nickel(II) with 1,3-bis(benzimidazol-2-yl) benzene-(bbzlH2bzH; L1), 1,3-bis(1-methylbenzimidazol-2-yl)-benzene (bbzlMe2bzH; L2) and 2,6-bis(1-methyl-benzimidazol-2-yl)pyridine (bbzlMe2py; L3) in stoichio-metric amounts in absolute ethanol-teof and acetone afforded a series of nickel(II).

Notes

 

1861

 

Pre-formed iron-thiosemicarbazone chelates as ribonucleotide reductase inhibitors

 

 

 

 

 

Anupa Murugkar,Subhash Padhye*& Lena Vorobjeva

 

 

     

 

1865

 

Photodegradation of malachite green in the aqueous medium

 

 

 

 

M A Hasnat, I A Siddiquey & Islam S M Saiful*

 

 

 

D + hn ® D*

D* + TiO2 ® D + + TiO2 (e)

TiO2 (e) + O2 ® TiO2 + O2· -

O2·- + 2H2O ® H2O2 + e

H2O2 + e ® ·OH + OH-

D· ++O2(or O2· - or ·OH)®Degraded products

 

 1868

 Electrical changes due to diffusion of physiologically important ions across an uncharged porous partition separating mixed electrolyte systems

 

 

 

R K Ram* & O N Tripathi

 

 

 

The EMF and current changes, due to chlorides of Na+, K+, Ca2+ have been studied across Whatman filter paper no. 42. The EMF and current generating capacity of these electrolytes both as MCIx and M’Cly, follow the order: KCI>NaCI > CaCl2.

 

 

1871

 

Ruthenium(III) catalysis of periodate oxidation of reducing sugars in aqueous alkaline medium

 

 

 

 

Ashok Kumar Singh*, Neena Gupta,
Shahla Rahmani, Vinod Kumar Singh &
Bharat Singh

 

 

 

The ruthenium(III) catalysis of periodate oxidation of
D-ribose, D-sorbose and maltose in aqueous alkaline medium has been investigated. The reactions are zero order with respect to each reducing sugar and first order with respect to ruthenium(III).

1876

 Temperature dependence of excess thermodynamic properties of binary mixtures consisting of propan-1-ol, butan-1-ol, pentan-1-ol, with 1,2-dibromoethane at different temperatures.

 

 

 

 T Satyanarayana Rao, N Veeraiah,
G Srinivasa Rao, D Ramachandran &
C Rambabu*

 

 

 

The densities, viscosities and ultrasonic velocities of binary mixtures of propan-1-ol, butan-1-ol and pentan-1-ol with 1,2-dibromoethane have been determined at 298.15, 303.15, 308.15 and 313.15 K over the entire composition range. The existence of molecular interaction in the mixtures is discussed based on the excess thermodynamic properties calculated using these values.

 

1883

 

Solution equilibria of mixed metal mixed ligand complexes of copper(II), nickel(II) and zinc(II) with glycylalanine and imidazole

 

 

 

 

Nripendra Singh, R N Patel*, K K Shukla &
P K Singh

 

 

 

Solution equilibria of mixed metal mixed ligand complexes of copper(II), nickel(II) and zinc(II) with glycylalanine and imidazole have been studied in aqueous solution by potentiometry, spectrophotometry and electron paramagnetic resonance spectroscopy.

 1888

 A soluble complex of Zn(II) with N2O4 core:  A structural study

 

 

 

 

 

 Ajay K Sah, Amjad Ali, E K Wegelius,
K Rissanen & Chebrolu P Rao*

 

 

 

1892

 

Reactions of [(Ar)Ru(PPh3)2(CH3CN)]X
(Ar = Cp*,
h5-C5Me5 and indenyl, h5-C9H7; X=PF6 or BF4) with terpyridines: Hypodentate nature of terpyridines (Phterpy, Pyterpy and Diterpy)

 

 

 

E K Rymmai & K Mohan Rao*

 

 

 

 

 

1896

 

Synthesis, characterization and biological studies of oxovanadium(IV), manganese(II), iron(II), cobalt(II),  nickle(II) and copper(II) complexes derived from a quadridentate ligand

 

 

P Venkateswar Rao* &
A Venkata Narasaiah

 

 

 

 1900

 Heterobinuclear cobalt-oxomolybdenum-thio-cyanate complexes of dithiocarbamates or
8-quinolinol

 

 

 

S James & K S Nagaraja*

 

 

 1905

 Synthesis, spectral and magnetic studies of some polynuclear, mixed-ligand complexes of iron and cobalt with 3-mercaptopropionic acid

 

 

 

  

B P Baranwal*, Tarkeshwar Gupta &
Atresh K Singh

 

 

 

1910

 

Poly(vinyl chloride) membrane containing zirconium(IV) selenomolybdate inorganic ion exchanger as dysprosium(III)-ion selective electrode

 

 

 

A P Gupta*, G L Verma & Himanshu Agarwal

 

 

Poly(vinyl chloride) supported tetracycline sorbed zirconium(IV) selenomolybdate chelating inorganic exchange membrane is employed for the determination of dysprosium(III) ion. It is successfully applied for the direct determination of Dy3+ in metaborate rock and as an indicator electrode in potentiometric titrations of dysprosium ion with 2-4 % experimental error.

 

 

1914

 

Studies on synergistic extraction of Pd(II) using thiosemicarbazone derivative of 2-OH/ naphthaldehyde and neutral donors

 

 

 

 

 

S Banerjee & S Basu*

 

 

 

The synergistic extraction of Pd(II) from aqueous hydrochloric acid medium, using thiosemicarbazone derivative of 2-OH′ naphthaldehyde in ethyl acetate is investigated in the presence of various neutral donors like amines and phosphorus oxides. Among the amines, the trend is found to be quarternary > tertiary > secondary and among the phosphorus oxide donors, it is phosphonate > trioctyl phosphine oxide > tributyl phosphine oxide > triphenyl phosphine oxide > tributyl phosphate.

1918

Announcement
             

 

Authors for correspondence are indicated by (*)

 

 

Indian Journal of Chemistry

Vol. 42A, August 2003, pp.1797-1814

 

 

Tailored ruthenium polypyridyl complexes as molecular electronic materials

L Mishra* , A K Yadaw & G Govil

 

In the present review, salient features of ruthenium polypyridyl complexes tailored for molecular electronic properties are presented. Attempts are also made to explore these newly synthesized materials in the construction of molecular wires, molecular rods, luminescence switches as well as sensors.

 

 

 

Indian Journal of Chemistry

Vol. 42A, August 2003, pp.1815-1821

 

 

Electronic structure of single stranded DNA base stacks

Shyam Kishor & A K Bakhshi*

 

The electronic density of states (DOS) curves of single stranded periodic and aperiodic DNA base stacks in B-conformation obtained with the help of simple negative factor counting (NFC) method are presented. Band structure results of polyadenine [poly (A)]; polyguanine [poly (G)]; polycytocine [poly (C)] and polythymine [poly (T)] obtained on the basis of ab initio Hartree Fock crystal orbital method using both minimal basis and double zeta basis sets have been used as input to calculate these DOS. In contrast to the periodic systems, the peaks in the DOS curves of the corresponding aperiodic systems are broader with fewer gaps in between for both levels of approximation. The calculated large values of bandgap obtained for these systems rule out the possibility of intrinsic conduction in them.

 

 

 

Indian Journal of Chemistry

Vol. 42A, August 2003, pp.1822-1826

  

 

On the electronic structures and conduction properties of
quasi-one dimensional model compositional
superlattices of type II-staggered

Parul Bhargava & A K Bakhshi*

 

The electronic spectra of three different quasi-one dimensional model compositional superlattices (copolymers) (AmBn)x belonging to the class of type-II staggered have been calculated in the tight binding approximation using a direct numerical approach. The trends in the structure and conduction properties as a function of (i) composition (m/n), (ii) block size m and n and (iii) arrangement of blocks in the copolymer chain for all the superlattices are discussed.

 

 

 

Indian Journal of Chemistry

Vol. 42A, August 2003, pp.1827-1832

 

 

Photocyclisation of phenylbenzoquinone: A time resolved photoacoustic calorimetric and flash photolytic study

Nitin Chattopadhyay,*, Carlos Serpa, Luis G Arnaut & Sebastião J Formosinho

 

Energetics of formation of the intermediate during the photocyclisation of phenylbenzoquinone (PBQ) to 2-hydroxydibenzofuran (HDBF) in methanol solvent has been investigated by employing the time-resolved photoacoustic calorimetric (TRPAC) technique. The study, in conjugation with the nanosecond/microsecond flash photolytic observations, confirms the formation of a long lived intermediate during the photocyclisation reaction. TRPAC result and semi-empirical (AM1 and PM3) calculations suggest that the intermediate is a biradical.

 

 

 

 

Indian Journal of Chemistry

Vol. 42A, August 2003, pp.1833-1839

 

 

La(1-x)AxMn(1-y)ByO3 supported on honeycomb substrate ¾ Characterization and application for catalytic converter

R B Biniwale*, M A Bawase, N K Labhsetwar & R Kumar

 

Perovskite catalysts are reported as substitute to noble-metal catalysts for automobile catalytic converter. The low surface area and non-compatibility with alumina washcoat had been the major problems for limiting the application of perovskite for auto-exhaust treatment. La0.7Sr0.3Mn0.95Pt0.05O3 supported on alumina washcoated honeycomb substrate has been prepared in this study. The detail characterization, at each step of preparation of catalyst coated substrate, using techniques such as BET SA, porosity, pore size distribution, TGA and XRD have been carried out and discussed. Characterization results reveal the possible use of supported perovskite for automobile exhaust treatment.

 

 

 

Indian Journal of Chemistry

Vol. 42A, August 2003, pp.1840-1849

 

  

Influence of sulphate content on the physico-chemical properties and catalytic activity of
some sulphated zirconia systems

Suja Haridas, C S Deepa, K Sreeja Rani & S Sugunan*

 

The present work attempts a systematic examination of the effect of sulphate content on the physico-chemical properties and catalytic activity of sulphated zirconia and iron promoted sulphated zirconia systems. Sulphate content is estimated by EDX analysis. The amount of sulphate incorporated has been found to influence the surface area, crystal structure and the acid strength distribution. Ammonia TPD and adsorption studies using perylene have enabled the determination of surface acidic properties. The results are supported by the thermodesorption studies using pyridine and 2,6-dimethylpyridine. The catalytic activity towards benzoylation reaction has been correlated with the surface acidity of the systems.

 

 

  

Indian Journal of Chemistry

Vol. 42A, August 2003, pp.1850-1855

 

 

A study of the ruthenium(III) catalysed oxidation of l-phenylalanine by heptavalent manganese—A kinetic and mechanistic approach

S A Chimatadar, A K Kini & S T Nandibewoor*

 

The kinetics of the ruthenium(III) catalysed oxidation of l-phenylalanine by alkaline permanganate has been studied spectrophotometrically using a rapid kinetic accessory. The reaction is first order each in [oxidant] and [catalyst] with an apparent less than unit order each in [substrate] and [alkali] respectively. The results suggest the formation of a complex between the phenylalanine and the hydroxylated species of ruthenium(III). The complex reacts further with the alkaline permanganate species in a rate-determining step, resulting in the formation of a free radical, which again reacts with the alkaline permanganate species in a subsequent fast step to yield the products. The reaction constants involved in the mechanism and the activation parameters have been calculated. There is a good agreement between observed and calculated rate constants under different experimental conditions.

 

  

 

Indian Journal of Chemistry

Vol. 42A, August 2003, pp.1856-1860

 

 

Monochelates and bischelates of nickel(II) with bis-benzimidazolyl derivatives

 Shivakumaraiah & N M Nanje Gowda*

 

The reaction of the hydrated halides/perchlorate of nickel(II) with bis-benzimidazolyl derivatives (I), namely, 1,3-bis(benzimidazol-2-yl) benzene(bbzlH2bzH; L1), 1,3-bis(1-methylbenzimidazol-2-yl)benzene (bbzlMe2bzH; L2) and 2,6-bis(1-methylbenzimidazol-2-yl)pyridine (bbzlMe2py; L3) in stoichiometric amounts in absolute ethanol-teof and acetone has afforded a series of nickel(II) complexes with the formulae NiX2L.nH2O (X = Cl or Br, L = L1 or L2, n = 2; X = I, L = L2, n = 1; X = Cl, Br or I, L = L3, n = 0), NiI2L1H2O.(CH3)2CO and Ni(L)2(ClO4)2.nH2O (L = L1 or L2, n = 0; L = L3, n = 2. The brown iodo complex, NiI2L3 turns green on exposure to atmosphere, giving NiI2L3.2H2O. The complexes have been characterised by elemental analyses, conductivity and magnetic measurements, infrared and electronic spectral studies as well as thermal analysis.

 

 

 

Indian Journal of Chemistry

Vol. 42A, August 2003, pp.1861-1864

 

 

Pre-formed iron-thiosemicarbazone chelates as
ribonucleotide reductase inhibitors

Anupa Murugkar ,  Subhash Padhye* & Lena Vorobjeva

 

Pre-formed iron(III) complexes of naphthoquinone thiosemicarbazone ligands, viz. 2-hydroxy-1,4-naphthoquinone-1-thiosemicarbazone (HNQTSC) and 2-thiosemicarbazido-1,4-naphthoquinone (TSCNQ) have been synthesized, characterized by various physical techniques and their potential for inhibition of ribonucleotide reductase (RDR) enzyme, crucial for DNA synthesis, has also been evaluated. It is observed that the pre-formed iron(III) complexes possess higher RDR inhibitory activity than the respective free ligands.

 

 

Indian Journal of Chemistry

Vol. 42A, August 2003, pp.1865-1867

 

 

Photodegradation of malachite green in the aqueous medium

M A Hasnat, I A Siddiquey & Islam S M Saiful*

 

TiO2 assisted photodegradation of malachite green (MG) has been examined in TiO2 dispersions under both UV and visible light and found that degradation is faster in UV-light (l 320 nm). Adsorption is prerequisite for the TiO assisted photodegradation and the extent of degradation have been discussed in terms of the Langmuir-Hinshelwood model. Like most semiconductors the photocatalytic nature of TiO2 is pH dependent because of its amphoteric nature. It has been found that pH ranging from 3-5 is suitable for the photodegradation of this system.

 

 

 

Indian Journal of Chemistry

Vol. 42A, August 2003, pp.1868-1870

 

 

Electrical changes due to diffusion of physiologically important ions across an uncharged porous partition separating mixed electrolyte systems

R K Ram* & O N Tripathi

 

The EMF and current changes, due to diffusion of mixed physiologically important ions (chlorides of Na+, K+, Ca++), have been studied, across Whatman filter paper no. 42 constituting the following concentration cell, reversible with respect to Cl.

Ag/AgCI MCIx (C1)+ MCly (C2)/ MCIx (C3) AgCI/Ag

 

The concentrations C1 and C3 of the electrolytes have been kept constant in each set of experiments, whereas that of M’Cly, C2, has been varied. An empirical equation for the EMF of this cell has been developed by modifying the Nernst equation. The yielded values are in good agreement with those observed experimentally. The EMF and current generating capacity of these electrolytes both as MCIx and M’Cly follow the order KCl>NaCI > CaCl2.

 

 

 

Indian Journal of Chemistry

Vol. 42A, August 2003, pp.1871-1875

 

 

Ruthenium (III) catalysis of periodate oxidation of reducing sugars in aqueous alkaline medium

Ashok Kumar Singh*, Neena Gupta, Shahla Rahmani, Vinod Kumar Singh &

Bharat Singh

 

The ruthenium (III) catalysis of periodate oxidation of D-ribose, D-sorbose and maltose in aqueous alkaline medium has been investigated. The reactions have been found to be zero order with respect to each reducing sugar and first order with respect to ruthenium (III). The linear dependence of the reaction rate at lower concentrations of periodate ion and hydroxide ion tends towards zero order at their higher concentrations. Positive effect of  on the rate of reaction has also been observed. The observed kinetics with periodate ion, under the conditions >>[Ru(III)]T suggests the formation of a 1:1 complex between Ru(III) and periodate in the rate controlling step, which subsequently interacts with reactive species of reducing sugar to give the final products, through a series of fast steps. The rate law is derived.

 

  

 

Indian Journal of Chemistry

Vol. 42A, August 2003, pp.1876-1882

 

  

Temperature dependence of excess   thermodynamic properties of binary mixtures consisting of propan-1-ol, butan-1-ol and pentan-1-ol, with 1,2-dibromoethane at different temperatures

T Satyanarayana Rao, N Veeraiah, G Srinivasa Rao, D Ramachandran & C Rambabu*

 

The densities, viscosities and ultrasonic velocities of binary mixtures of propan-1-ol, butan-1-ol and pentan-1-ol with 1,2-dibromoethane have been determined at 298.15, 303.15, 308.15 and 313.15 K over the entire composition range. The above experimental data has been utilized to estimate excess acoustic impedance (ZE), excess isentropic compressibility (KsE), excess free volume (VfE) and internal pressure (pi) values to discuss the existence of molecular interaction in the mixtures.

 

 

 

Indian Journal of Chemistry

Vol. 42A, August 2003, pp.1883-1887

 

 

 Solution equilibria of mixed metal mixed ligand complexes of copper(II), nickel(II) and zinc(II) with glycylalanine and imidazole

 Nripendra Singh, R N Patel* , K K Shukla & P K Singh

 

Solution equilibria of mixed metal mixed ligand complexes of CuII, NiII and ZnII with glycylalanine and imidazole investigated in aqueous solution by potentiometry, spectrophotometry and electron paramagnetic resonance spectroscopy. The stability constants of the binary, ternary and quaternary complexes are determined and it is obtained for the following species (A- = glycylalaniate and B= imidazole) : M2+, AH2+, AH, A-, BH+, B, M(OH)+, M(OH)2, M(A)+, M(A)(OH), M(B)2+, M(B)(OH)+, M(A)(B)+, M2(A)2(B)2+, M2(A)2(B-H)+, M1M2(A)2(B)2+ and M1M2(A)2(B-H)+. (N1H) deprotonation of bidentate coordinated bridging imidazole ligand in the binuclear complexes at pH>6.5 is evident from spectral measurements. Stability constants of binary M(A)+, M(B)2+ and ternary M(A)(B)+ complexes follow Irving-Williams order.

 

 

 

Indian Journal of Chemistry

Vol. 42A, August 2003, pp.1888-1891

 

 

A soluble complex of Zn(II) with N2O4 core:
A structural study

Ajay K Sah, Amjad Ali, E K Wegelius, K Rissanen & Chebrolu P Rao*

 

A soluble complex of Zn(II) with 1-hydroxy-3-hydroxy-2-hydroxymethyl-2-(5¢-formyl-salicylidimino) propane resulting in a distorted octahedral ZnN2O4 core has been synthesized and characterized by analytical and spectral methods and the structure has been established by single crystal XRD

 

 

Indian Journal of Chemistry

Vol. 42A, August 2003, pp.1892-1895

 

 

Reactions of [(Ar)Ru(PPh3)2(CH3CN)]X 
 (Ar=Cp*, h5-C5Me5 and indenyl, h5-C9H7; X=PF6 or BF4) with terpyridines: Hypodentate nature of terpyridines
(Phterpy, Pyterpy and Diterpy)

 E K Rymmai & K Mohan Rao*

  

Ligand displacement reactions of the complexes of the type(Ar)Ru(PPh3)2(CH3CN)]PF6 {Ar=Cp* (1) and indenyl (2)} have been investigated with N3-terpyridine ligands, 4¢-phenyl-2,2¢:6¢,2¢¢ terpyridine (phterpy), 4¢-(4¢¢¢-pyridyl)-2,2¢:6¢,2¢¢ terpyridine (pyterpy) and 1,4-bis(2,2¢:6,6¢¢ terpyridin-4-yl) benzene (diterpy). The complexes [(Ar)Ru(PPh3)2(CH3CN)]PF6 {Ar=Cp* (1) and indenyl (2)} are reacted with these ligands to form  stable complexes of the type [Cp*Ru(PPh3)(phterpy)]BF4 (3), [Cp*Ru(PPh3)(pyterpy)]BF4 (4), [(h5ind)Ru(PPh3)(phterpy)]PF6 (5), [(h5ind)Ru(PPh3)(pyterpy)]PF6 (6), [(Cp*Ru(PPh3)}2 (diterpy)](BF4)2 (7) and [(h5ind)Ru(PPh3)}2(diterpy)](PF6)2 (8) where respective ligands are coordinated in a bidentate fashion. When these reactions are carried out with chloro analogues [Cp*Ru(PPh3)2Cl] (9) and [(h5-ind)Ru(PPh3)2Cl] (10) with respective ligands viz. phterpy and pyterpy, a mixture of products are isolated including the complex type 3-6 and [RuCl(PPh3)2(N3-phterpy)]PF6 (11) and [RuCl(PPh3)2(N3-pyterpy)]PF6 (12) respectively. All these complexes have been characterized by spectral and analytical data.

 

 

  

Indian Journal of Chemistry

Vol. 42A, August 2003, pp.1896-1899

 

 

Synthesis, characterization and biological studies of oxovanadium(IV), manganese(II), iron(II), cobalt(II), nickle(II) and copper(II) complexes derived from a quadridentate ligand

P Venkateswar Rao* & A Venkata Narasaiah

 

The solid complexes of oxovanadium(IV), Mn(II), Fe(II), Co(II), Ni(II) and (Cu(II) with a new quadridentate ligand (DHACH), derived from 3-acetyl-6-methyl-2H-pyran-2,4 (3H)-dione (dehydroacetic acid) and carbohydrazide, have been synthesized and characterized by analytical, conductivity, thermal, magnetic, IR, 1H NMR, UV-vis, mass and ESR spectral data. From the analytical and thermal data, the stoichiometry of the complexes has been found to be 1:1 (metal:ligand). The metal chelates have a general formula [M(DHACH).2H2O], where M=Mn(II), Fe(II), Co(II), Ni(II) and Cu(II). Oxovanadium(IV) complex has the composition [VO(DHACH).H2O]. IR spectral data suggest that the ligand, DHACH behaves as a dibasic quadridentate ligand with O:N:N:O donor sequence towards metal ions. The physico-chemical data suggest that all the complexes possess ocatahedral stereochemistry. The fungicidal activities of the ligand and the metal complexes have been screened in vitro against the organism Aspergillus niger and the percentage of inhibition has been found to be in the order:

Cu(II)>Ni(II)>Fe(II)>Co(II)>Mn(II)>VO(IV)

 

 

 

Indian Journal of Chemistry

Vol. 42A, August 2003, pp.1900-1904

 

 

Heterobinuclear cobalt-oxomolybdenum-thiocyanate complexes of dithiocarbamates or 8-quinolinol

 S James & K S Nagaraja*

 

 The heterobinuclear complexes of [CoMoO2(NCS)(L)3(H2O)] (L=diethyldithiocarbamate, 4-morpholinyldithiocarbamate or 8-quinolinol) are prepared by the interaction of ammonium molybdate with ammonium thiocyanate in the presence of hydrazinium sulphate and cobalt(II) nitrate with the respective ligands in DMF. The magnetic moment, EPR and PES data suggest the presence of molybdenum(V) and low-spin cobalt(III). The crystal field splitting parameters have been evaluated from the electronic spectral data. The infrared spectra suggest the presence of N-bonded thiocyanate ligand (2040 and 780 cm-1), dithiocarbamate ligands (1500 and 960 cm-1) and (Mo=O) (910 cm-1) in the molecule. The extensive splitting in each peak observed in the 1H NMR spectra of the complexes indicate the restricted rotation of the alkyl side chain of the bidentate dithiocarbamate groups. The redox behaviour of the complexes in DMF is discussed from the cyclic voltammetry data. The thermal decomposition and infrared spectral studies confirm the presence of coordinated water molecule. The proposed structure consists of an octahedral cobalt(III) and an octahedral oxomolybdenum(V) bridged by an oxo and a thiocyanate groups.

 

   

 

Indian Journal of Chemistry

Vol. 42A, August 2003, pp.1905-1909

 

 

Synthesis, spectral and magnetic studies of some polynuclear, mixed-ligand complexes of iron and cobalt with 3-mercaptopropionic acid

B P Baranwal*, Tarkeshwar Gupta & Atresh K Singh

 

Some mixed-ligand, trinuclear complexes of mixed-valence iron (III, III, II) and dinuclear cobalt(II) have been synthesized by enforced substitution of acetate ions from their respective acetato complexes. The isolated products of the types [Fe3O(OOCR)3(OOCRSH)3] and [Co(OOCR)(OOCRSH)]2 (where R = C7H15, C11H23 or C15H31 and R = -CH2CH2-) are mixed (carboxylato)(mercaptocarboxylato) complexes. These have been characterized by microanalytical data and infrared, UV-visible and Mössbauer spectra. Non-electrolytic behaviour and polynuclear nature of the complexes have been assessed from their low conductance and high molecular weight data. The octahedral environment around both the metals has been suggested on the basis of UV-visible and magnetic moment data. Mössbauer studies reveal two resolved quadrupole doublets due to Fe(II) and Fe(III) confirming the valence-localised classification of the iron compounds.

 

 

  

Indian Journal of Chemistry

Vol. 42A, August 2003, pp.1910-1913

 

 
Poly(vinyl chloride) membrane containing zirconium(IV)selenomolybdate inorganic ion exchanger as dysprosium(III)-ion selective electrode

 A P Gupta*, G L Verma & Himanshu Agarwal

 

Poly(vinyl chloride) supported tetracycline sorbed zirconium(IV) selenomolybdate chelating inorganic exchange membrane has been employed for the determination of dysprosium(III) ion. The membrane electrode shows a Nernstain response for Dy(III) over a wide concentration range (1.0×10-1 M - 5×10-5 M) with a slope of 18.3 mV per decade of concentration. The detection limit is 3.8×10-5 M. The electrode is found to possess adequate stability and specific selectivity for Dy(III) over the other closely trivalent lanthanide metal ions with a response time of ~ 15 s. The sensor can also be used in partially non-aqueous medium, e.g., acetone/alcohol having 5-10% (v/v) contents. Its working pH range is 2-9. It is successfully applied for the direct determination of Dy3+ in metaborate rock and as an indicator electrode in potentiometric titrations of dysprosium ion with 2-4 % experimental error.

  

 

 

 Indian Journal of Chemistry

Vol. 42A, August 2003, pp.1914-1917

 

 

Studies on synergistic extraction of Pd (II) using thiosemicarbazone derivative of 2-OH¢ naphthaldehyde and neutral donors

S Banerjee & S Basu*

 

The synergistic extraction of Pd(II) from aqueous hydrochloric acid medium, using thiosemicarbazone derivative of 2-OH¢ naphthaldehyde in ethyl acetate has been investigated in the presence of various neutral donors like amines (TOA, Amberlite LA-2 and Adogen-464) and phosphorus oxides (TOPO, phosphonate, TBPO, TPPO and TBP). The overall equilibrium constant (log K) for the ternary species [Pd(A)ClS], where S is donor and A is the ligand, has been calculated for various systems. The values of synergistic co-efficient and adduct formation constant in organic phase (b) for the amine donors are found to be greater than those for the phosphorus oxide donors. Among the amines, the trend is found to be quarternary > tertiary > secondary and among the phosphorus oxide donors, it is phosphonate > trioctyl phosphine oxide (TOPO) > tributyl phosphine oxide (TBPO) > triphenyl phosphine oxide (TPPO) > tributyl phosphate (TBP). Effects of pH variation and nature of various diluents on the synergistic extraction of Pd (II) have also been studied. The procedure has been applied to the estimation of Pd (II) in rock samples.