Total visitors:2,322 since 7-06-05

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

 

 

 

VOLUME 44A

NUMBER 4

APRIL 2005

 

 

CONTENTS

 

Papers

 657

Quantum chemical studies on some selenanaphthalene derivatives

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Lemi Türker

 

Quantum chemical studies on certain selenanaphthalene derivatives (having a keto or enol group and also Se atom in five- or six-membered ring system fused with naphthalene moiety) have been carried out using PM3 method at the level of restricted Hartree-Fock approach. The aquated systems have also been considered.

 

 661

 Solid-state reaction between p-benzoquinone and
p-aminophenol

 

 

 

 

  

 

N B Singh

 

Kinetics of solid-state reaction between p-benzoquinone and p-aminophenol is reported at different temperatures. It has been found that rate constants when the reactants are in contact and when they are separated by air gaps of different lengths are not the same. The energy of activation determined by this method is found to be much higher than that for surface migration, indicating that the molecules of p-benzoquinone enter into the crystal lattice of p-aminophenol forming the reaction product in 1:1 molar ratio.

667

Photoreduction of Co(en)2Cl(RC6H4NH2)2+ in water – isopropanol solutions: Solvent and structure reactivity correlation analysis

 

 

 

 

 

 

K Anbalagan

 

Photoreduction quantum yields of Co(en)2Cl(RC6H4NH2)2+ (where R = p–OMe, p-OEt, p-Me, m-Me, H and p-F) in water-isopropanol mixtures (15, 20, 25, 30, 35 and  40% (v/v) organic cosolvent) at 25°C, ionic strength I = 0.1M (NaNO3), have been subjected to phenomenological model of solvent effect. The quantum yield values obtained from different solvent compositions are fitted into a simple and multiple regression model equations to understand and quantify medium influence.

 673

Electronic structure of SRY gene

 

 

 

 

 

Shyam Kishor & A K Bakhshi*

 

The electronic density of states (DOS) distributions of SRY gene present on Y chromosome of homo-sapiens obtained with the help of negative factor counting (NFC) method using tight binding approximation are presented. The Y chromosome-specific gene SRY is one of the key genes involved in human sex determination.

678

Coenzyme B12 model studies: Equilibria and kinetics of axial ligation of alkyl(aquo)cobaloximes by  N donor ligands

 

 

 

 

 

 

 

 

D Sudarshan Reddy, B Krishna Rao, P Pallavi, N Navaneetha & S Satyanarayana*

 

Equilibria and kinetics of the reaction of trifluoroethyl(aquo)cobaloxime and iodomethyl(aquo)-cobaloxime with histamine,  histidine, glycine and ethyl glycine ester have been studied as a function of pH at 25°C,1.0M KCl ionic strength by spectrophotometry technique. Comparison of equilibrium constants and rate constants indicates that the order is KHisdn>KHiamn> KGly>KGlyest. The rate of substitution of H2O varies with the pKa of the incoming ligand establishing the existence of nucleophilic participation of the ligand in the transition state. Triflouroethyl(aquo)cobaloxime forms more stable complexes than iodomethyl(aquo)cobaloxime.

687

Synthesis, structure and luminescence behaviour of complexes of type [Cd(dpa)2X2] (dpa = 2,2¢-dipyridylamine; X = N3-, NCS-, NCO-)

 

 

 

 

 

 

 

 

 

 

 

Habibar Chowdhury, Rajarshi Ghosh, S K Hafijur Rahaman, Georgina M Rosair & Barindra K Ghosh*

 

The synthetic details and characterization data of three mononuclear complexes of the type [Cd(dpa)2X2] (dpa = 2,2¢-dipyridylamine; X = N3-, 1; X = NCS-, 2 and X = NCO-, 3) are described.

693

Mixed ligand transition metal(II) complexes of Knoevenagel condensate-b-ketoesters with 1,2-diaminobenzene: Synthesis, structural characterization, electrochemical behaviour and antimicrobial study

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

N Raman*, C Thangaraja & S Johnson Raja

 

New Schiff base mixed ligand transition metal complexes of the composition, [ML(DB)2]Cl2, where M=Cu(II), Ni(II), Co(II) and Zn(II); L=Knoevenagel condensate-b-ketoester derived from 1-hydroxybenzaldehyde and methyl ester of 3-oxobutanoic acid (HMOA)/ethyl ester of 3-oxobutanoic acid (HEOA)/N-phenyl-2-oxobutanamide (HPOB) and 1,2-diaminobenzene(DB), are reported.

 

 700

Synthesis, characterisation and polarographic studies of diastereoisomeric [Cu(Me8[14]ane)](ClO4)2 complexes

 

 

T G Roy* & R Bembi

 

The isomeric Me8[14]anes designated by LA, LB and LC undergo facile complexation with copper(II) perchlorate hexahydrate to give two N-chiral isomers in each case. The isomers show distinct colour variation (red to violet) and distinct variations in infrared spectra specially in fingerprint region.

705

 Synthesis, spectra, redox property and catalytic activity of ruthenium(III)

Schiff base complexes

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

G Venkatachalam, S Maheswaran & R Ramesh*

 

 A series of ruthenium(III) complexes of the type [RuX2(EPh3)2(L)] (where E= P or As, X= Cl or Br; L = bidentate Schiff bases) have been synthesized and characterized on the basis of analytical (elemental analysis, magnetic susceptibility) and spectral methods (FT-IR, UV-vis, EPR). EPR spectra of the powdered samples exhibit three lines with different ‘g’ values indicating a rhombic distortion in these complexes. These complexes effectively catalyze the oxidation of primary alcohols to their corresponding aldehydes up to 91.5% in the presence of N-methylmorpholine-N-oxide (NMO) as co-oxidant.

 

Notes

 710

Mechanism of peroxide reactions: Kinetics of oxidation of  aromatic aldehydes by peroxomonosulfuric acid

 

 

 

 

 

 

 

 

 

 

Radhasyam Panda* & Prabhat Ku. Acharya 

 

The kinetics of oxidation of benzaldehyde and p-nitrobenzaldehyde by peroxomonosulfuric acid (PMSA) have been carried out over a wide pH range 0-9.5 at 35°C. The reactions obey second order kinetics, first order each in [PMSA] and [substrate]. The observed v-shaped pH-rate profile has been rationalised by invoking , , the protonated and unprotonated forms of aldehyde as the reactive species, and a suitable rate law has been proposed. The mechanism of oxidation involves rate-determining nucleophilic attack of the peroxo anion on carbonyl-carbon of the substrate species, followed by hydride ion shift and oxygen-oxygen bond fission to yield the products.

 715

Kinetics and mechanism of oxidation of beta benzoylpropionic acids by pyridinium fluorochromate in aqueous acetic acid medium

 

 

 

 

 

 

 

 

 

 

S Kavitha, A Pandurangan* & I Alphonse

 

The kinetics of oxidation of beta benzoylpropionic acid and para substituted beta benzoylpropionic acids(KA) by pyridinium fluorochromate(PFC) has been studied in aqueous acetic acid medium in the presence of perchloric acid. The reaction follows first order kinetics each with respect to [PFC], [KA] and [H+]. Electron withdrawing substituents are found to retard the reaction and electron releasing substituents are found to increase the rate of reaction and the rate data obey the Hammett relationship. The products of the oxidation are the corresponding acids. The activation enthalpies and entropies are calculated and the possible mechanism for oxidation reaction is discussed.

719

Calcium chloride influenced surface and bulk properties of Triton X-100 in aqueous medium

 

 

 

   

Ram Partap*, Neelam Swaroop , D K Tyagi & O P Yadav

 

The critical micelle concentration (CMC) of iso-octyl phenoxy polyethoxy ethanol (TritonX-100 or TX-100) and its maximum surface excess concentration (Gmax), minimum area per molecule (Amin) at the air-liquid interface have been tensiometrically determined in presence of calcium chloride at 288, 293 and 298K. Thermodynamic parameters of micellization as well as of adsorption at the air-liquid interface have been evaluated and discussed.

723

Reactions of [(m-H)Os3(CO)8 {Ph2PCH2P(Ph)C6H4}] and [Os3(CO)10  (m-dppm)] with 2-mercaptoimidozole, 2-mercaptobenzimidazole and 2-mercapt-obenzothiazole: X-ray structure of [(m-H)Os3(CO)8(m-dppm)(m-h1-SN2C3H3)]

 

 

 

 

 

 

 

 

 

  

 

 

 

 

 

Noorjahan Begum, Md Manjur Hassan, G M Golzar Hossain & Shariff E Kabir*

 

 The electron-deficient compound [(m-H)Os3(CO)8 {Ph2PCH2P(Ph)C6H4}] 2 reacts with 2-mercaptoimidozole, 2-mercaptobenzimidazole and 2-mercaptobenzothiazole at 80°C to give [(m-H)Os3(CO)8(m-dppm)(m-h1-SN2C3H3)] 3, [(m-H)Os3 (CO)8(m-dppm)(m-h1-SN2C7H5)] 4 and [(m-H)Os3(CO)8(m-dppm)(m-h1-S2NC7H4)] 5 in 30, 50 and 59% yields, respectively.

 729

Synthesis and characterisation of
5,6-bis(salicylideneimino)-1,10-phenanthroline and its trinuclear complexes

 

 

 

  

 

 

Nebahat Demirhan*, Ulvi Avcıata & Ahmet Gül

 

 

733

Determination of free and total zinc using 2-[(5-bromo-2-pyridylazo)]-5-diethylaminophenol in mixed surfactant medium

 

Ravi Kumar Banjare, Manisha Thakur &
Manas Kanti Deb* 

 

 A simple and sensitive spectrophotometric method for chemical fractionation and determination of zinc in cosmetics and pharmaceuticals is described based on the formation of red coloured species of Zn(II) with 2-[(5-bromo-2-pyridylazo)]-5-diethylaminophenol (5-Br-PADAP) and mixed surfactants (TX-100 and Brij-35).

 737

Spectrophotometric method for the simultaneous determination of piroxicam and 2-aminopyridine

 

 

 

 

 

L Suntornsuk*, P Bunavitayakij & P Pitayatienanan

 

A rapid and simple spectrophotometric method is proposed for the simultaneous determination of piroxicam (Pi) and 2-aminopyridine (2-Ap). The method is based on the measurement of absorbances of 2-Ap and Pi at 300 and 360 nm, respectively, and the calculations are based on the binary method. The method has been applied for the determination of Pi and 2-Ap in piroxicam capsules.

 Authors or correspondence are indicated by (*)

 

 

Indian Journal of Chemistry

 Vol. 44A, April 2005, pp. 657-660

 

Quantum chemical studies on some selenanaphthalene derivatives

Lemi Türker

 

Quantum chemical studies on certain selenanaphthalene derivatives (having a keto or enol group and also Se atom in five- or six-membered ring system fused with naphthalene moiety) have been carried out using PM3 method at the level of restricted Hartree-Fock approach. The aquated systems have also been considered.

 

 

 

Indian Journal of Chemistry

 Vol. 44A, April 2005, pp. 661-666

 

Solid-state reaction between p-benzoquinone and p-aminophenol

N B Singh

 

Kinetics of solid-state reaction between p-benzoquinone and p-aminophenol has been studied at different temperatures. When the reactants are kept in contact in glass capillaries, the reaction rate increases with temperature and energy of activation is found to be much lower than the heat of sublimation of p-benzoquinone. It has been found that rate constants when the reactants are in contact and when they are separated by air gaps of different lengths are not the same. The results show that the diffusion of p-benzoquinone molecules towards p-aminophenol occurs via surface migration. Kinetics of reaction between p-benzoquinone (vapour) and p-aminophenol (solid) has also been studied by gravimetric method. The energy of activation determined by this method is found to be much higher than that for surface migration, indicating that the molecules of p-benzoquinone enter into the crystal lattice of p-aminophenol forming the reaction product in 1:1 molar ratio. Elemental analysis shows that stoichiometry of the reaction products obtained from solution and solidstate reaction is the same. UV-vis and infrared spectral studies indicate that the reaction product obtained from solution may be charge transfer complex stabilized by hydrogen bond. PMR, X-ray diffraction and DTA studies show that the reaction products obtained from the two different routes are different.

 

IPC Code: Int. Cl7. C0750/04

 

 

 

Indian Journal of Chemistry

 Vol. 44A, April 2005, pp. 667-672

 

Photoreduction of Co(en)2Cl(RC6H4NH2)2+ in water – isopropanol solutions: Solvent and structure reactivity correlation analysis

K Anbalagan

Photoreduction quantum yields of Co(en)2Cl(RC6H4NH2)2+ (where R = p–OMe, p-OEt, p-Me, m-Me, H and p-F) in water-isopropanol mixtures (15, 20, 25, 30, 35 and 40% (v/v) organic cosolvent) at 25°C, ionic strength I = 0.1M (NaNO3), have been subjected to phenomenological model of solvent effect. The quantum yield values obtained from different solvent compositions are fitted into a simple and multiple regression model equations to understand and quantify medium influence. The solvent effects are explained by statistical equations, which can establish nonspecific (Laidler-Eyring, 1/er plot), specific (extended Krygowski-Fawcett’s, ETN and β) and both nonspecific/specific (Kamlet-Taft’s, α , β, and π*) solvation effects. A quantitative measure on solvation effect using the respective coefficients is attempted. The observed substituent effect (Hammett’s σ plot) is explained for the electronic contribution leading to stability of excited state [CoIII -L]2+ or less polar geminate radical pair [CoII .L]2+. From the results it is concluded that photoreduction proceeds through a less polar geminate radical pair [CoII .L]2+ that is stabilized by an electron donating group (p-OMe) of the sixth ligand (RC6H4NH2) or by decreasing the polarity of the medium.

 

 

 

Indian Journal of Chemistry

 Vol. 44A, April 2005, pp. 673-677

 

Electronic structure of SRY gene

Shyam Kishor & A K Bakhshi*

 

The electronic density of states (DOS) distributions of SRY gene present on Y chromosome of homo-sapiens obtained with the help of negative factor counting (NFC) method using tight binding approximation are presented. The Y chromosome-specific gene SRY is one of the key genes involved in human sex determination. 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. The calculated large values of band gap obtained for these systems are comparable to those of aperiodic DNA base stacks and rule out the possibility of intrinsic conduction in them.

 

 

 

Indian Journal of Chemistry

 Vol. 44A, April 2005, pp. 678-686

 

Coenzyme B12 model studies: Equilibria and kinetics of axial ligation of alkyl(aquo)cobaloximes by  N donor ligands

D Sudarshan Reddy, B Krishna Rao, P Pallavi, N Navaneetha & S Satyanarayana*

 

Equilibria and kinetics of the reaction of trifluoroethyl(aquo)cobaloxime and iodomethyl(aquo)cobaloxime with histamine,  histidine, glycine and ethyl glycine ester have been studied as a function of pH at 25°C,1.0M KCl ionic strength by spectrophotometry technique. Comparison of equilibrium constants and rate constants indicates that the order is KHisdn>KHiamn> KGly>KGlyest. The rate of substitution of H2O varies with the pKa of the incoming ligand establishing the existence of nucleophilic participation of the ligand in the transition state. The rate constants and equilibrium constants are correlated to the hardness and softness of the ligands and Co(III) of cobaloxime. Triflouroethyl(aquo)cobaloxime forms more stable complexes than iodomethyl(aquo)cobaloxime.

 

IPC Code: Int Cl.7 C07F 15/06

 

 

 

Indian Journal of Chemistry

 Vol. 44A, April 2005, pp. 687-692

 

Synthesis, structure and luminescence behaviour of complexes of type [Cd(dpa)2X2] (dpa = 2,2¢-dipyridylamine; X = N3-, NCS-, NCO-)

Habibar Chowdhury, Rajarshi Ghosh, Sk Hafijur Rahaman, Georgina M Rosair & Barindra K Ghosh*

 

The synthetic details and characterization data of three mononuclear complexes of the type [Cd(dpa)2X2] (dpa = 2,2¢-dipyridylamine; X = N3-, 1; X = NCS-, 2 and X = NCO-, 3) are described. In one case, [Cd(dpa)2(NCS)2] (2), X-ray structure determination has been made for the exact definition of the coordination sphere. Structural analysis reveals that the cadmium(II) centre is in a distorted octahedral environment with a CdN5S chromophore with two dpa units roughly perpendicular to one another and the two thiocyanates in mutual cis orientation with one in S-bound and the other in N-bound states. The mononuclear unit packs through N-H…S and N-H…N hydrogen bonding to have a one-dimensional (1D) chain. Spectroscopic and other physicochemical data show that compounds 1 and 3 have the cognate structure. The compounds display high energy intraligand 1(p-p*) fluorescence and intraligand 3(p-p*) phosphorescence in glassy solutions (DMF at 77 K). A band (near 375 nm) observed for all the complexes in their solid state emission spectra is an excimeric emission. The role of dpa, a tailored diimine with active amine hydrogen and aromatic pyridine ring, is discussed towards functionalisation on crystal engineering and luminescence behaviour.

 

IPC Code: Int Cl.7 C07F3/08; C09K11/08

 

 

 

Indian Journal of Chemistry

Vol. 44A, April 2005, pp. 693-699

 

Mixed ligand transition metal(II) complexes of Knoevenagel condensate-b-ketoesters with 1,2-diaminobenzene: Synthesis, structural characterization, electrochemical behaviour and antimicrobial study

N Raman*, C Thangaraja & S Johnson Raja

 

New Schiff base mixed ligand transition metal complexes of the composition, [ML(DB)2]Cl2, where M=Cu(II), Ni(II), Co(II) and Zn(II); L=Knoevenagel condensate-b-ketoester derived from 1-hydroxybenzaldehyde and methyl ester of 3-oxobutanoic acid (HMOA)/ethyl ester of 3-oxobutanoic acid (HEOA)/N-phenyl-2-oxobutanamide (HPOB) and 1,2-diaminobenzene(DB), were synthesized. They were characterized on the basis of elemental analyses, magnetic susceptibility, FAB-mass, electronic absorption spectra, IR, 1H NMR, 13C NMR and ESR data. All the complexes exhibit octahedral geometry. Their magnetic susceptibility measurements and conductance data provide evidence for the monomeric and 1:2 electrolytic natures of the complexes, respectively. The electrochemical behaviour, the anodic and cathodic potential and the number of electron transfer were calculated using cyclic voltammogram. The antimicrobial activities of the ligand and its complexes have been studied by screening the compounds against various microorganisms (both Gram-positive and Gram-negative bacteria) and the results have been compared with the standard drug, ampicillin. The data showed that the complexes were highly active than that of the free ligand and the standard.

 

IPC Code: Int.Cl.7 C07F1/08; C07F15/04; C07F15/66; C07F3/06

 

 

 

Indian Journal of Chemistry

 Vol. 44A, April 2005, pp. 700-704

 

Synthesis, characterisation and polarographic studies of diastereoisomeric [Cu(Me8[14]ane)](ClO4)2 complexes

T G Roy* & R Bembi

 

The isomeric Me8[14]anes designated by LA, LB and LC undergo facile complexation with copper(II) perchlorate hexahydrate to give two N-chiral isomers in each case. The isomers show distinct colour variation (red to violet) and distinct variations in infrared spectra specially in fingerprint region. The square planar geometry and stereochemistry of them have been assigned on the basis of analytical, conductometric, magnetochemical and spectroscopic data. Comparison of the d-d bands for the various copper(II) macrocyclic complexes leads to the conclusion that 5,6,5,6 sequence chelate ring is ideal for stable coordination with copper(II). The polarographic reduction of these complexes shows a single diffusion controlled one electron transfer reversible wave due to the Cu(II)/Cu(I) couple.

 

IPC Code: Int.Cl.7 C07F1/08; G01N27/48

 

 

 

Indian Journal of Chemistry

Vol. 44A, April 2005, pp. 705-709

 

Synthesis, spectra, redox property and catalytic activity of ruthenium(III) Schiff base complexes

G Venkatachalam, S Maheswaran & R Ramesh*

 

A series of ruthenium(III) complexes of the type [RuX2(EPh3)2(L)] (where E= P or As, X= Cl or Br; L = bidentate Schiff bases) have been synthesized and characterized on the basis of analytical (elemental analysis, magnetic susceptibility) and spectral methods (FT-IR, UV-vis, EPR). EPR spectra of the powdered samples exhibit three lines with different ‘g’ values indicating a rhombic distortion in these complexes. Cyclic voltammogram of the complexes displays one reversible oxidation (RuIV/RuIII) and two reversible reduction peaks (RuIII/RuII, RuII/RuI) with DEp=60-80 mV suggesting one electron transfer process. These complexes effectively catalyze the oxidation of primary alcohols to their corresponding aldehydes up to 91.5% in the presence of N-methylmorpholine-N-oxide (NMO) as co-oxidant. The formation of high-valent Run+2=O species as catalytic intermediate is proposed for the catalytic processes.

 

IPC Code: Int. Cl.7 C07F15/00; B01J23/46

 

 

 

Indian Journal of Chemistry

 Vol. 44, April 2005, pp. 710-714

 

Mechanism of peroxide reactions: Kinetics of oxidation of aromatic aldehydes by peroxomonosulfuric acid

Radhasyam Panda* & Prabhat Ku Acharya

 

The kinetics of oxidation of benzaldehyde and p-nitrobenzaldehyde by peroxomonosulfuric acid (PMSA) have been carried out over a wide pH range 0-9.5 at 35°C. The reactions obey second order kinetics, first order each in [PMSA] and [substrate]. The observed v-shaped pH-rate profile has been rationalised by invoking , , the protonated and unprotonated forms of aldehyde as the reactive species, and a suitable rate law has been proposed. The mechanism of oxidation involves rate-determining nucleophilic attack of the peroxo anion on carbonyl-carbon of the substrate species, followed by hydride ion shift and oxygen-oxygen bond fission to yield the products. The activation parameters of the reactions are reported.

 

IPC Code: Int. Cl.7 C07B33/00

 

 

 

Indian Journal of Chemistry

 Vol. 44A, April. 2005, pp. 715-718

 

Kinetics and mechanism of oxidation of beta benzoylpropionic acids by pyridinium fluorochromate in aqueous acetic acid medium

S Kavitha, A Pandurangan* & I Alphonse

 

The kinetics of oxidation of beta benzoylpropionic acid and para substituted beta benzoylpropionic acids(KA) by pyridinium fluorochromate(PFC) has been studied in aqueous acetic acid medium in the presence of perchloric acid. The reaction follows first order kinetics each with respect to [PFC], [KA] and [H+]. Electron withdrawing substituents are found to retard the reaction and electron releasing substituents are found to increase the rate of reaction and the rate data obey the Hammett relationship. The products of the oxidation are the corresponding acids. The activation enthalpies and entropies are calculated and the possible mechanism for oxidation reaction is discussed.

 

IPC Code: Int. Cl.7 C07B33/00

 

 

 

Indian Journal of Chemistry

Vol. 44A, April 2005, pp. 719-722

 

Calcium chloride influenced surface and bulk properties of Triton X-100 in aqueous medium

Ram Partap*, Neelam Swaroop, D K Tyagi & O P Yadav

 

The critical micelle concentration (CMC) of iso-octyl phenoxy polyethoxy ethanol (TritonX-100 or TX-100) and its maximum surface excess concentration (Gmax), minimum area per molecule (Amin) at the air-liquid interface have been tensiometrically determined in presence of calcium chloride at 288, 293 and 298K. Thermodynamic parameters of micellization as well as of adsorption at the air-liquid interface have been evaluated and discussed.

 

IPC Code: Int. Cl.7 C01F 11/00

 

 

 

Indian Journal of Chemistry

Vol.44A, April. 2005, pp. 723-728

 

Reactions of [(m-H)Os3(CO)8- {Ph2PCH2P(Ph)C6H4}] and [Os3(CO)10(m-dppm)] with 2-mercaptoimidozole, 2-mercaptobenzimidazole and 2-mercapt-obenzothiazole: X-ray structure of [(m-H)Os3(CO)8(m-dppm)(m-h1-SN2C3H3)]

Noorjahan Begum, Md Manjur Hassan, G M Golzar Hossain & Shariff E Kabir*

 

The electron-deficient compound [(m-H)Os3(CO)8- {Ph2PCH2P(Ph)C6H4}] 2 reacts with 2-mercaptoimidozole, 2-mercaptobenzimidazole and 2-mercaptobenzothiazole at 80°C to give [(m-H)Os3(CO)8(m-dppm)(m-h1-SN2C3H3)] 3, [(m-H)Os3- (CO)8(m-dppm)(m-h1-SN2C7H5)] 4 and [(m-H)Os3(CO)8(m-dppm)(m-h1-S2NC7H4)] 5 in 30, 50 and 59% yields, respectively. The compounds are formed by the oxidative addition of S-H bond followed by demetallation of the phenyl ring of the orthometallated dppm ligand. Compounds 3-5 have also been obtained from the reactions of [Os3(CO)10(m-dppm)] 1 with 2-mercaptoimidozole, 2-mercaptobenzimidazole and 2-mercaptobenzothiazole, respectively at 110°C but in some what lower yields. The compounds have been characterized by elemental analysis, IR, 1H NMR and 31P{1H} NMR spectroscopic data together with single crystal X-ray diffraction studies for 3. Compound 3 crystallizes in the triclinic space group P1 with a=11.3453(12), b=13.651(2), c=15.069(2) Å, a=84.709(11), b=72.706(9), g=68.265(9)°, Z=2 and V=2069.5(4) Å3. The structure consists of an equilateral triangle of osmium atoms with a bridging dppm, a bridging hydride and a bridging 2-mercaptoimidazolato ligand.

 

IPC Code: Int. Cl7. C07F15/00

 

 

 

Indian Journal of Chemistry

Vol. 44A, April 2005, pp. 729-732

 

Synthesis and characterisation of 5,6-bis(salicylideneimino)-1,10-phenanthroline and its trinuclear complexes

Nebahat Demirhan*, Ulvi Avcıata & Ahmet Gül

 

As a multidonor ligand with phenanthroline and salicylaldimine functionalities on the same molecule, 5,6-bis(salicylideneimino)-1,10-phenanthroline (LH2) has been synthesized by the reaction of 5,6-diamino-1,10-phenanthroline with salicylaldehyde and its metal complexes with Ni(II) and Cu(II) have been prepared. Both of the isolated complexes are trinuclear with metal/ligand ratio of 3:2. Protonation constants of LH2 which have been determined by potentiometric titration in solution are log K1=8.96, log K2=15.88, log K3=8.73 and log K4=2.78. The newly synthesized compounds have been verified by IR, 1H NMR and mass spectra together with elemental analysis.

 

IPC Code: Int. Cl.7 C07F1/08

 

 

 

Indian Journal of Chemistry

Vol. 44A, April 2005, pp. 733-736

 

Determination of free and total zinc using 2-[(5-bromo-2-pyridylazo)]-5-diethylaminophenol in mixed surfactant medium

Ravi Kumar Banjare, Manisha Thakur & Manas Kanti Deb*

 

A simple and sensitive spectrophotometric method for chemical fractionation and determination of zinc in cosmetics and pharmaceuticals is described based on the formation of red coloured species of Zn(II) with 2-[(5-bromo-2-pyridylazo)]-5-diethylaminophenol (5-Br-PADAP) and mixed surfactants (TX-100 and Brij-35) in the pH range 8.2-10.5. The red coloured Zn(II)-5-Br-PADAP-(TX-100+Brij-35) complex in aqueous medium shows maximum absorbance at 550 nm with molar absorptivity of 1.60´105 dm3 mol-1 cm-1. The detection limit of the method is 6 ng Zn(II)/cm2 and obeys Beer’s law up to 0.4 mg Zn(II)/ cm2 in aqueous phase. Relative standard deviation for ten determinations for solution containing 0.2 mg Zn(II)/cm2 is 1.5%. The validity of the method has been satisfactorily examined for the determination of zinc (free and total) in cosmetics and pharmaceutical formulating samples manufactured in India, with RSD value from actual analyte content ranging between 2.1 and 2.7% for cosmetics and between 1.9 and 2.8% for pharmaceutical formulations.

 

IPC Code: Int. Cl.7: C07F3/06

 

 

 

Indian Journal of Chemistry

Vol. 44A, April 2005, pp. 737-740

 

Spectrophotometric method for the simultaneous determination of piroxicam and 2-aminopyridine

L Suntornsuk*, P Bunavitayakij & P Pitayatienanan

 

A rapid and simple spectrophotometric method is proposed for the simultaneous determination of piroxicam (Pi) and 2-aminopyridine (2-Ap). Piroxicam is stable under basic hydrolysis, but yields 2-Ap as one of the degradation products under acid hydrolysis. The method is based on the measurement of absorbances of 2-Ap and Pi at 300 and 360 nm, respectively, and the calculations are based on the binary method. The absorbances of both compounds obey Beer-Lambert’s law over the concentration range of 5-25 mg L-1 with good linearity (r2>0.99). The recoveries are within 100.8-106.4% for Pi and are within 96.4-98.9% for 2-Ap. Precision is good with acceptable limits of detection (LOD) and quantitation (LOQ) for both compounds. The method has been applied for the determination of Pi and 2-Ap in piroxicam capsules. The average content of two different brands of piroxicam is 97.4 and 98.5% (n = 3), which complies with the USP 26 (92.5-107.5%). Under the stress condition (refluxing with 0.1 N HCl), the percentages of piroxicam decrease from 100% (0 h) to 18.9% (21 h) and 2-Ap increase from 0% (0 h) to 63.6% (21 h).

 

IPC Code: Int. Cl7. G01N21/00