Indian Journal of Chemistry

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

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VOLUME 49A

NUMBER 2

February 2010

CONTENTS

 

145

 

DFT studies on hydrogen bonded complexes of thymine with formamide

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Yan-min Li, Xin-ming Zhou*, Ke Tang,
Mei Qin, Zheng-yu Zhou*

 

 

 

 

H bond interactions of the thymine-formamide complexes have been investigated by the B3LYP method. The structures of four possible cyclic double H-bonded complexes have been fully optimized at 6-31+G(d), 6-311++G(d, p) and 6-311++G(2d, 2p). The relative orders of the occupancies of σ* (Y-H) and E(2) are consistent with the order of the corresponding
H bond strengths.

 

 

 

 

 

151

 

Theoretical studies on model Type II staggered conducting superlattices

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Swati Agrawal & A K Bakhshi*

 

 

 

Quasi-one-dimensional model diblock and triblock polymeric superlattices belonging to Type II-staggered have been investigated using Deans negative factor counting method in tight binding approximation. Increasing the block size of all the components is found to result in copolymers with band gap lower than that of the homopolymers. The electronic properties of the copolymers lie intermediate of those of the three components. The DOS curves of periodic copolymers consist of sharp peaks while those of aperiodic copolymers consist of broad regions of allowed energy states with fewer gaps in between.

 

 

159

 

Intramolecularly H-bonded bis-benzimidazole diamide ligand and its Mn(II) complexes: Synthesis, spectral and electrochemical studies

 

 

 

 

 

 

 

 

 

 

 

Subash Chandra Mohapatra, Ruchi Bakshi,
M S Hundal & Pavan Mathur*

 

 

 

New manganese(II) complexes with a diamide ligand
N,N-bis(benzimidazolyl-2yl)(methyl)pentane diamide have been synthesized with the general composition, [Mn(GBGA)2X2], where X = Cl-, CH3COO-, SCN-, ClO4-. The ligand has been structurally characterized and is found to adopt a helical structure stabilized by strong intramolecular and intermolecular H-bonding. The ligand crystallizes in the monoclinic space group P21/c with unit cell dimensions:
a = 14.180(5) , b = 8.454(5) , c = 19.353(5) , α= 90.000, β=108.232(5), γ = 90.000 and Z=2. X-band solid state EPR spectra for the Mn(II) complexes indicate weakly distorted octahedral complexes with D in the range 0.05-0.14 cm-1. Cyclic voltammograms display a quasi-reversible redox wave. The E1/2 values follow the order: SCN- < CH3COO- < Cl- ~ ClO4-. Quenching of superoxide anion is studied by cyclic voltammetry.

Notes

 

167

 

Synthesis and structural characterization of a new ruthenium hydride ethylene complex

 

 

 

 

 

 

 

 

 

 

C M Nagaraja, Munirathinam Nethaji &
Balaji R Jagirdar*

 

 

 

A new ruthenium(II) hydride ethylene
complex, viz., trans-[Ru(H)(C2H4)(dppm)2][BF4], bearing

1,1-bis(diphenylphosphino)methane, has been synthesized and structurally characterized by X-ray crystallography.

 

 

 

171

 

Synthesis, characterization and ferromagnetic behavior of [CoIII(en)2(RC6H4NH2)I]I2.H2O complexes

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

K Anbalagan*, A S Ganeshraja & S Kandasamy

 

 

 

Mixed ligand cobalt(III) complexes containing aryl amine (RC6H4NH2) ligand have been synthesized. A wide range of complexes, [CoIII(en)2(L)I]I2.H2O, (where L = RC6H4NH2;
R = m-OMe, p-F, H, m-Me, p-Me, p-OEt and p-OMe) show promising reactivities and physical properties due to the presence of electron donor/acceptor groups in the aryl ligand.
Magnetic studies yield magnetic remanence in the range of 7.071x10-3 3.069x10-5 emu/g and intrinsic coercivity in the range,
141-1156 Oe. A modified ferromagnetic character due to charge build up on the metal centre by ligating nitrogen atom has been observed, which in turn makes the molecule into a centre of systematic variation in magnetization.

 

 

176

 

A DFT and AIM study of the interactions of pyridine and pyrazine with alkali hydrides. Identification of dihydrogen bonds involving aromatic C-H hydrogen

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Amit K Samanta & Dipankar Datta*

 

 

 

The interactions of pyridine and pyrazine with LiH, NaH and KH have been studied by DFT at the B3LYP/6-311++g(2d,p) level. The interaction energies corrected for BSSE lie in the range −86.7 to −38.8 kJ mol-1. A dihydrogen bond (of distance 2.27 ) between H1 and H2 is revealed by B3LYP/6-311++g(2d,p) calculations and subsequent AIM analyses in the interaction of pyridine with KH. A shorter dihydrogen bond (2.17 ) is observed for pyrazine-KH.

 

 

 

 

 

180

 

 

 

Prediction of viscosity for R142b, R152a at the zero density regime by a semi-empirical method

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Behzad Haghighi*, Fatemeh Heidari &
Mohammad Mehdi Papari

 

 

 

A new inversion method is presented for obtaining the interaction potential pairs for 1-choloro-1,1-difluoroethane and
1,1-difluoroethane utilizing the extended corresponding states approach. The calculated inverted potentials have been used in evaluating the viscosity coefficients for gaseous state of both the compounds in dilute gas density regime. Due to the iterative nature of the present method the Lennard-Jones 12-6 (LJ 12-6) potential model has been implemented initially. The interaction potential energies from the inversion method reproduce the viscosity and are commensurate within the uncertainty of the best measurements which can be applied to a wide span of temperature range. The reduced collision integrals and their ratios have also been estimated.

 

 

 

 

 

185

 

 

 

A kinetic study on Ru(III)catalysed oxidation of mercaptosuccinic acid by methylene blue in acidic medium

 

 

 

 

 

 

 

 

 

 

 

 

K K Mishra*, Ranu Chaturvedi & M Shukla

 

 

 

Mercaptosuccinic acid and methylene blue interact in a molar ratio of 2:1 in presence of hydrochloric acid and Ru(III) as a catalyst in aqueous acetone medium (40% v/v) forming dithiodimalic acid and dihydromethylene blue. The reaction follows half order kinetics in methylene blue. The order in mercaptosuccinic acid is unity. The average value of half order rate constant remains practically unaffected on varying [H+] up to 2.0 10-2 M. The order in methylene blue changes from 1/2 to 1 at lower [H+] (1.0 10-2 M) as well as at lower concentrations of catalyst (1.0 10-5 M), while at higher [Ru (III)] (≥ 2.0 10-5 M) the order in the oxidant becomes zero.

 

Authors for correspondence are indicated by (*)

 

 

Indian Journal of Chemistry

Vol. 49A, February 2010, pp. 145-150

 

DFT studies on hydrogen bonded complexes of thymine with formamide

Yan-min Lia,b, Xin-ming Zhoua,b,*, Ke Tangc, Mei Qinc & Zheng-yu Zhouc,*

aCollege of Chemistry & Chemical Engineering, China University of Petroleum, Shangdong,
DongYing, 257061, Peoples Republic of China

bDepartment of Culture Foundational Education, Shandong Business Institute, Shandong,
Yantai 264025, Peoples Republic of China

cDepartment of Chemistry, Qufu Normal University, Shandong, Qufu 273165, Peoples Republic of China

Email: zhengyu@mail.qfnu.edu.cn

Received 15 September 2009; revised and accepted 25 January 2010

Hydrogen bond interactions of the thymine-formamide complexes have been investigated using B3LYP method. The structures of four possible cyclic double H-bonded complexes have been fully optimized at 6-31+G(d), 6-311++G(d, p) and 6-311++G(2d, 2p), respectively. Upon complexation with formamide, the thymine monomer undergoes some deformation of the bonds, especially in the interaction of strong H bonds. Within one complex, the N(T)-HO(F) bond is stronger than the N(F)-HO(T) bond. Natural bond orbital analysis indicates that all atoms of thymine experience a charge redistribution upon complexation with formamide, especially those involved in the formation of H bonds. The relative orders of the occupancies of σ* (Y-H) and E(2) are consistent with the order of the corresponding H bonds strengths. An analysis of vibrational frequency shifts and IR intensities shifts has also been carried out.

 

Keywords: Theoretical chemistry, Density functional calculations, Hydrogen bond interactions, Thymine, Formamide

 

 

Indian Journal of Chemistry

Vol. 49A, February 2010, pp. 151-158

 

Theoretical studies on model Type II staggered conducting superlattices

Swati Agrawala & A K Bakhshib, *

aMoti Lal Nehru College, University of Delhi, Delhi 110 021, India

bDepartment of Chemistry, University of Delhi, Delhi 110 007, India

Email: akbakhshi2000@yahoo.com/ swatichem@gmail.com

Received 19 August 2009 ; revised and accepted 20 January 2010

Quasi-one-dimensional model diblock and triblock polymeric superlattices belonging to Type II- staggered have been investigated using Deans negative factor counting method in tight binding approximation. For each system, the trends in electronic properties i.e., IP, EA and band gap, have been studied as a function of block size, composition, arrangement of blocks and type of polymer chain (periodic or aperiodic). The trends for triblock systems obtained have been compared with the corresponding trends for diblock copolymers. Increasing the block size of all the components is found to result in copolymers with band gap lower than that of the homopolymers. The electronic properties are found to lie intermediate of the electronic properties of the three components. The DOS curves of periodic copolymers consist of sharp peaks while those of aperiodic copolymers consist of broad regions of allowed energy states with fewer gaps in between.

 

Keywords: Theoretical chemistry, Polymers, Copolymers, Conducting Polymers, Electronic properties, Density of states

 

 

Indian Journal of Chemistry

Vol 49A, February 2010, pp. 159-166

 

Intramolecularly H-bonded bis-benzimidazole diamide ligand and its Mn(II) complexes: Synthesis, spectral and electrochemical studies

Subash Chandra Mohapatraa, Ruchi Bakshia, M S Hundal b & Pavan Mathura,*

aDepartment of Chemistry, University of Delhi, Delhi 110 007, India

bGuru Nanak Dev University, Amritsar 143 005, India

Email: pavanmat@yahoo.co.in

Received 2 July 2009; revised and accepted 14 January 2010

New manganese(II) complexes with a diamide ligand N,N'-bis(benzimidazolyl-2yl)(methyl)pentane diamide have been synthesized with the general composition [Mn(GBGA)2X2] where X = Cl-, CH3COO-, SCN-, ClO4-. The ligand has been structurally characterized and has been found to adopt a helical structure stabilized by strong intramolecular and intermolecular H-bonding. The ligand crystallizes in the monoclinic space group P21/c with unit cell dimensions: a = 14.180(5) , b = 8.454(5) , c = 19.353(5) , α= 90.000, β=108.232(5), γ = 90.000 and Z=2. X-band solid state EPR spectra for the Mn(II) complexes have been obtained indicating weakly distorted octahedral complexes with D ranging between 0.05-0.14 cm-1. Cyclic votammograms display a quasi-reversible redox wave. The E1/2 values follow the order: SCN- < CH3COO- < Cl- ~ ClO4-. Quenching of superoxide anion is studied by cyclic voltammetry. From the plot of total peak current versus concentration of the added Mn(II) catalysts, the break points and turnover of catalyst have been evaluated.

 

Keywords: Coordination chemistry, Superoxides, Superoxide quenching, Manganese, Amides

IPC Code: Int. Cl. 9 C07F13/00

 

 

Indian Journal of Chemistry

Vol. 49A, February 2010, pp. 167-170

 

Synthesis and structural characterization of a new ruthenium hydride ethylene complex

C M Nagaraja, Munirathinam Nethaji & Balaji R Jagirdar*

Department of Inorganic & Physical Chemistry Indian Institute of Science, Bangalore 560 012, India
Email:
jagirdar@ipc.iisc.ernet.in

Received 20 October 2009; accepted 12 January 2010

A ruthenium(II) ethylene complex, trans-[Ru(H)(C2H4)-(dppm)2][BF4], bearing two 1,1-bis(diphenylphosphino) methane (dppm) ligands has been synthesized and structurally characterized using X-ray crystallography. In the molecular structure, the RuII center shows a distorted octahedral coordination geometry formed by four P atoms of the two chelating dppm ligands, a hydride, and an ethylene ligands. The four dppm P atoms are almost co-planar with the hydride and the ethylene ligands perpendicular to this plane. The C-C bond distance of the bound ethylene is 1.375(6) , which is elongated by 0.042 as compared to free ethylene (1.333(2) ). The packing diagram of the complex shows two voids or channels, which are occupied by BF4 counterion and water molecules.

 

Keywords: Coordination chemistry, Ruthenium, Dihydrogen complexes, Hydrides

IPC Code: Int. Cl.9 C007F15/00

 

 

Indian Journal of Chemistry

Vol 49A, February 2010, pp. 171-175

 

Synthesis, characterization and ferromagnetic behavior of [CoIII(en)2(RC6H4NH2)I]I2.H2O complexes

K Anbalagan*, A S Ganeshraja & S Kandasamy

Department of Chemistry, Pondicherry University, Kalapet, Pondicherry 605 014, India

Email: kanuniv@gmail.com

Received 24 August 2009; revised and accepted 21 January 2010

Mixed ligand cobalt(III) complexes containing aryl amine (RC6H4NH2) ligand have been synthesized using a modified route developed in this study. A wide range of complexes, [CoIII(en)2(L)I]I2.H2O, (where L = RC6H4NH2; R = m-OMe, p-F, H, m-Me, p-Me, p-OEt and p-OMe) show promising reactivities and physical properties due to the presence of electron donor/acceptor groups in the aryl ligand. The complexes have been characterized by elemental analysis, FT-IR, UV-vis and powder X-ray diffraction patterns. FT-IR ν(M-X) and UV-vis spectral data are compatible with trans-form of the complexes. Magnetic studies yield magnetic remanence Mr = 7.071 10-3 3.069 10-5 emu/g and intrinsic coercivity, -Hci = 141-1156 Oe. Linear regression plot of Mr versus σ yields negative slope, implying that electron withdrawing group in RC6H4NH2 (σ > 0) enhances ferromagnetic character while the electron donating groups (σ < 0) reduce ferromagnetism. The study provides evidence that substitution at the aryl ligand, remote from the Co(III) center, effectively displays and imparts characteristic ferromagnetic properties. Cobalt(III) complexes containing RC6H4NH2 ligand illustrate a simple molecular fabrication technique, which can be suitably integrated into a system, to have some control on the behavior of metal complexes. A modified ferromagnetic character due to charge build up on the metal centre by ligating nitrogen atom, which in turn makes the molecule into a centre of systematic variation in magnetization, has been observed.

 

Keywords: Coordination chemistry, Ferromagnetism, Cobalt, Aryl amines

IPC Code: Int. Cl.9 C07F15/06

 

 

Indian Journal of Chemistry

Vol. 49A, February 2010, pp. 176-179

 

A DFT and AIM study of the interactions of pyridine and pyrazine with alkali hydrides. Identification of dihydrogen bonds involving aromatic C-H hydrogen

Amit K Samanta & Dipankar Datta*

Department of Inorganic Chemistry, Indian Association for the Cultivation of Science, Kolkata 700 032, India
Email: icdd@iacs.res.in

Received 30 October 2009; revised and accepted 11 January 2010

The interactions of pyridine (py) and pyrazine (pz) with LiH, NaH and KH are studied by DFT at the B3LYP/6-311++g(2d,p) level. The interaction energies corrected for BSSE lie in the range −86.7 to −38.8 kJ mol-1. Dihydrogen bonds are observed only for the py-KH and pz-KH systems with distances 2.27 and 2.17 respectively. AIM analyses show presence of bond critical points, associated with an electron density of 0.011-0.013. Our calculations on the ammonia borane dimer, where presence of dihydrogen bond is authentic, at the same level of theory reveal that the electron density at the bond critical points of the dihydrogen bonds (of calculated lengths 2.03-2.05 ) is 0.015.

 

Keywords:Theoretical chemistry, Density functional calculations, Atom-in-molecule analysis, Dihydrogen bonds, Bond critical point, Interaction energy, Ammonia borane dimer

 

 

Indian Journal of Chemistry

Vol. 49A, February 2010, pp. 180-184

 

 

Prediction of viscosity for R142b, R152a at the zero density regime by a
semi-empirical method

Behzad Haghighia, *, Fatemeh Heidaria & Mohammad Mehdi Paparib

aThermodynamic and Transport Properties Research Laboratory (T&TPRL), Department of Chemistry, University of Birjand, Postal Code 97175-615, Birjand, Southern Khorasan Province, Iran

Email: BHaghighi@birjand.ac.ir/ haghighi.behzad@gmail.com

 

bChemistry Department, Shiraz University of Technology, Shiraz, Fars Province, 71555-313, Iran

Received 15 June 2009; revised and accepted 18 January 2010

An new inversion method is presented for obtaining the interaction potential pairs for 1-choloro-1,1-difluoroethane and 1,1-difluoroethane utilizing the extended corresponding states approach of Huber et al. [Huber M L, Laesecke A, Perkins R A, Ind Eng Chem Res, 42 (2003) 3163]. The calculated inverted potentials have been used in evaluating the viscosity coefficients for gaseous state of both the compounds in dilute gas density regime. Due to the iterative nature of the present method the Lennard-Jones 12-6 (LJ 12-6) potential model has been implemented initially. The interaction potential energies from the inversion method reproduce the viscosity and are commensurate within the uncertainty of the best measurements which can be applied to a wide span of temperature range. The reduced collision integrals and their ratios have also been estimated.

Keywords: Theoretical chemistry, Transport properties, Refrigerants, Viscosity, Interaction potential, Collision integrals, Inversion method

 

 

Indian Journal of Chemistry

Vol. 49A, February 2010, pp. 185-189

 

A kinetic study on Ru(III)catalysed oxidation of mercaptosuccinic acid by methylene blue in acidic medium

K K Mishra*, Ranu Chaturvedi & M Shukla

Department of Postgraduate Studies and Research in Chemistry, Rani Durgavati University, Jabalpur 482 001, India

Email: kkmishra.chem@gmail.com/ ranu_jbp@rediffmail.com

Received 22 July 2009; revised and accepted 13 January 2010

Mercaptosuccinic acid and methylene blue interact in a molar ratio of 2:1 in presence of hydrochloric acid and Ru(III) as a catalyst in aqueous acetone medium (40% v/v) forming dithiodimalic acid and dihydromethylene blue. The reaction follows a half order kinetics in methylene blue. The order in mercaptosuccinic acid is unity. The average value of half order rate constant remains practically unaffected on varying [H+] up to 2.0 10-2 M. The order in methylene blue changes from 1/2 to 1 at lower [H+] (1.0 10-2 M) as well as at lower concentrations of catalyst (1.0 10-5 M), while at higher [Ru (III)] (≥ 2.0 10-5 M) the order in the oxidant becomes zero. This indicates that the relationship between the rate constant and [Ru(III)] is not simple. The rate constant decreases on increasing the time of equilibration of Ru(III) with other ingredients of the reaction system. SEM images suggest the formation of square shaped crystals with size ranging between 50-200 μm. The addition of reaction products does not influence the rate. Activation parameters have been evaluated and a plausible reaction scheme, presuming the reaction between the transient complex (Ru(III)SR) and MBH+ as the rate determining step, has been proposed.

 

Keywords: Kinetics, Reaction mechanisms, Oxidations, Dyes, Methylene blue, Ruthenium

IPC Code: Int. Cl.9 C07B33/00