NOPR Collection:

Axial binding of 2-methylimidazole to the tetraarylcarboxylatodiruthenium (II, III) core: X-ray crystal structure of [Ru₂(O₂CC₆H₄-p-OMe)₄ (2-mimH)₂](CIO₄). 1.75CH₂CI₂.H₂O

Thu, 01 Jan 1998 00:00:00 GMT

Title: Axial binding of 2-methylimidazole to the tetraarylcarboxylatodiruthenium (II, III) core: X-ray crystal structure of [Ru₂(O₂CC₆H₄-p-OMe)₄ (2-mimH)₂](CIO₄). 1.75CH₂CI₂.H₂O Authors: Sudha, Chellamma; Chakravarty, Akhil R Abstract: Diruthenium (II. III) complexes of the type [RU₂(O₂CAr)₄ (2- mimH)₂](CIO₄) (Ar = C₆H₄-P-X : X=OMe.l: X=Me. 2: 2-mimH=2- methylimidazole) have been isolated from the reaction of RU₂CI(O₂CAr)₄ with 2- mimH in CH₂Ch followed by the addition of NaCIO_4. The crystal structure of 1. 1.75CH₂CI₂.H₂O has been determined, The crystal belongs to the monoclinic space group p21/c with the following unit cell dimensions for the C₄₀H₄₀N₄O₁₆CIRu₂. I.75CH₂CI₂.H₂O (M= 1237.0) : a = 12.347 (3)Å. b = 17615(5) Å,c = 26.148(2) Å.b = 9288(l)⁰,v = 5679(2) Å '. Z=4. D_c = 1.45 g cm^-3 λ (Mo- Ka) = 0.7107 Å. µ(Mo-Ka) = 8.1 cm^-1. T= 293 K. R = 0.0815 (wR² =0.2118) for 5834 reflections with 1 > 2 s(I). The complex has a tetracarboxylatodiruthenium (II. III) core and two axially bound 2-methylimidazole ligands. The Ru-Ru bond length is 2.290( I) Å. The Ru-Ru bond order is 2.5 and the complex is three-electron paramagnetic. The complex shows an irreversible RU₂(II, III) RU₂(II, II) reduction near -0.2 V vs SCE in CH₂CI₂-0.1 MTBAP. The complexes exemplify the first adduct of the tetracarboxylatodiruthenium (II,III) core having N-donor ligands. Page(s): 1-6

Metalloenzyme biosensors:Part 1 - Amperometric tyrosinase biosensor for phenols using composite biopolymer matrix

Thu, 01 Jan 1998 00:00:00 GMT

Title: Metalloenzyme biosensors:Part 1 - Amperometric tyrosinase biosensor for phenols using composite biopolymer matrix Authors: Kulkarni, Pallavi; Karve, Meena; Kumbhar, Avinash; Padhye, Subhash Abstract: An amperometric biosensor has been prepared by immobilizing plant tyrosinase enzyme in a novel composite polysaccharide gel matrix on the tip of a glassy carbon electrode and used for the measurements of Dopa substrates in aqueous medium in the concentration range 10^-4 to 10^-2 mol I^-1. The sensor has a shelf-life of four months. Parameters affecting the performance of the sensor have also been evaluated. Page(s): 7-10

Kinetics and mechanism of formation of binary and ternary complexes of nickel(II) and nickel(II)-2- aminomethylbenzimidazole with 3-nitrosalicylate and cis- (ammine )(3-nitrosalicylato) bis (ethylenediamine)cobalt(III) : Evidence for the slow interconversion of the structural isomers of the ternary complexes

Thu, 01 Jan 1998 00:00:00 GMT

Title: Kinetics and mechanism of formation of binary and ternary complexes of nickel(II) and nickel(II)-2- aminomethylbenzimidazole with 3-nitrosalicylate and cis- (ammine )(3-nitrosalicylato) bis (ethylenediamine)cobalt(III) : Evidence for the slow interconversion of the structural isomers of the ternary complexes Authors: Dash, Anadi C; Sahoo, Rama K; Acharya, Achyuta N Abstract: The kinetics of complex formation of 3-nitrosalicylate(NSAH^-) and cis-(en)₂(NH₃)(3-nitrosalicylato)cobalt(III) with Ni(OH₂)₆²⁺ and [Ni(AMB)(OH₂)₄]²⁺ (AMB = 2- aminomethylbenzimidazole) have been investigated. The formation of the ternary complexes [Ni(AMB)(NSA)(OH₂)₂] and [(en)₂(NH₃)Co{NSA=Ni(AMB)(OH₂)₂} ]³⁺ displayed biphasic kinetics due to the slow and reversible structural isomerisation (trans- (diaqua) species Û cis-( diaqua) species). The formation of [Ni(NSA)(OH₂)₄] is chelation-controlled. The isomerisation of the ternary complexes is presumed to involve Ni- N (benzimidazolyl-N) bond cleavage and rearrangement of the intermediate. Page(s): 11-20

Kinetics and mechanism of oxidation of ascorbic acid by cobalt(III) complexes in micellar media

Thu, 01 Jan 1998 00:00:00 GMT

Title: Kinetics and mechanism of oxidation of ascorbic acid by cobalt(III) complexes in micellar media Authors: Makote, Rajendra D; Chatterjee, C Abstract: The kinetics of oxidation of L-ascorbic acid (H₂A) by Co(bipy)₃³⁺, Co(edta)^- and Co(atda) (tmd) complexes have been studied spectrophotometrically in the presence of cationic, cetyl trimethylammonium bromide (CTAB) and anionic sodium dodecylsulphate (SDS) surfactants in weakly acidic and basic media. The rate of ascorbic acid oxidation is influenced by the ionic nature of the micelle, hydrophobicity of the coordinated ligands and the overall charge of the complex used. Ascorbic acid oxidation by Co(bipy)₃³⁺ is slowed down in the presence of SDS while rate acceleration is observed in CTAB micellar medium. CTAB micelles also lead to rate enhancement in ascorbic acid oxidation by Co(edta)^- complex. However. micellar effect is not very pronounced in the case of neutral Co(atda) (tmd) complex as oxidant. Based on kinetic results it can be inferred that the hydrophobic interactions are dominant in the case of Co(bipy)₃³⁺ and electrostatic interactions play an important role for Co(edta)^- complex. Page(s): 21-25

NOPR Collection:

Axial binding of 2-methylimidazole to the tetraarylcarboxylatodiruthenium (II, III) core: X-ray crystal structure of [Ru2(O2CC6H4-p-OMe)4 (2-mimH)2](CIO4). 1.75CH2CI2.H2O

Metalloenzyme biosensors:Part 1 - Amperometric tyrosinase biosensor for phenols using composite biopolymer matrix

Kinetics and mechanism of oxidation of ascorbic acid by cobalt(III) complexes in micellar media

Axial binding of 2-methylimidazole to the tetraarylcarboxylatodiruthenium (II, III) core: X-ray crystal structure of [Ru₂(O₂CC₆H₄-p-OMe)₄ (2-mimH)₂](CIO₄). 1.75CH₂CI₂.H₂O