Synthesis, characterization, DNA binding and catalytic applications of Ru(III) complexes.

A new series of azodye ligands 5-chloro-3-hydroxy-4-(aryldiazenyl)pyridin-2(1H)-one (HLn) were synthesized by coupling of 5-chloro-3-hydroxypyridin-2(1H)-one with aniline and its p-derivatives. These ligands and their Ru(III) complexes of the type trans-[Ru(Ln)2(AsPh3)2]Cl were characterized by elemental analyses, IR, (1)H NMR and UV-Visible spectra as well as magnetic and thermal measurements. The molar conductance measurements proved that all the complexes are electrolytes. IR spectra show that the ligands (HLn) acts as a monobasic bidentate ligand by coordinating via the nitrogen atom of the azo group (NN) and oxygen atom of the deprotonated phenolic OH group, thereby forming a six-membered chelating ring and concomitant formation of an intramolecular hydrogen bond. The molecular and electronic structures of the investigated compounds (HLn) were also studied using quantum chemical calculations. The calf thymus DNA binding activity of the ligands (HLn) and their Ru(III) complexes were studied by absorption spectra and viscosity measurements. The mechanism and the catalytic oxidation of benzyl alcohol by trans-[Ru(Ln)2(AsPh3)2]Cl with hydrogen peroxide as co-oxidant were described.

Synthesis, spectral and catalytic dehydrogenation studies of ruthenium complexes containing NO bidentate ligands.

The synthesis and characterization of ruthenium mononuclear complexes containing NO bidentate ligands are reported. The complexes cis-[Ru(II)(bpy)2L](PF6)n (1a-c), [Ru(III)Cl(L)2(H2O)] (2a-b) and [Ru(III)Cl2(L)2]Cl (2c) were prepared by the reaction of cis-[Ru(II)Cl2(bpy)2]·2H2O (bpy=2,2'-bipyridine) and/or RuCl3·nH2O with the Ligands: 2-aminophenol (2-aph), 8-hydroxyquinoline (8-hq) and 4-aminoantipyrine (4-apy). These complexes were characterized by elemental analysis, spectroscopic (IR, UV-Vis, (1)H NMR, ESR) and magnetic susceptibility measurements. The ligand field parameters, Δo (splitting parameter), B (Racah parameter of interelectronic repulsion), and ß (nephelauxetic ratio) were calculated. The redox properties were also investigated electrochemically by cyclic voltammetry. The complexes cis-[Ru(II)(bpy)2(8-hq)](PF6)2 (1b) and [Ru(III)Cl(8-hq)2(H2O)] (2b) have been investigated in conjunction with N-methylmorpholine-N-oxide (NMO) as co-oxidant for the catalytic dehydrogenation of benzyl amine, p-methyl benzylamine and p-nitrobenzylamine to their respective nitriles.

Synthesis, spectroscopic characterization, redox properties and catalytic activity of some ruthenium(II) complexes containing aromatic aldehyde and triphenylphosphine or triphenylarsine.

A series of new mixed ligand penta-coordinated square pyramidal ruthenium(II) complexes containing benzaldehyde or its substituents and triphenylphosphine or triphenylarsine have been synthesized and characterized. In the electronic spectra, three well-defined peaks in the visible region were observed and assigned to d-d transitions in D(4h) and low spin axially distortion from O(h) symmetry. The spectrochemical parameters of the complexes were calculated and placed the ligands in the middle of the spectrochemical series. The redox properties and stability of the complexes toward oxidation were related to the electron-withdrawing or releasing ability of the substituent in the phenyl ring of the benzaldehyde. The electron-withdrawing substituents stabilized Ru(2+) complexes, while electron-donating groups favored oxidation to Ru(3+). The mechanism and kinetics of the catalytic oxidation of benzyl alcohol by the complex [RuCl(2)(Pph(3))(C(6)H(5)CHO)(2)] in the presence of N-methylmorpholine-N-oxide have also been studied.

Stereochemistry of new nitrogen containing heterocyclic aldehyde. VIII. Spectral and coordination modes of mixed-ligand of novel ruthenium(III) complexes.

Reaction of 8-hydroxy-7-quinolinecarboxaldehyde (LH) with RuC3 x XH2O afforded the compounds [RuL3] and/or [RuL2CIOH2]. Reactions of LH with RuCl3 x XH2O in the presence of N-heterocyclic bases led to the formation of complexes of type [RuL2 x ClPy] and [RuLCl2(o-Phen)] (Py = pyridine or o-Phen = 1,10-phenanthroline). The amine exchange reactions of coordinated Schiff bases in these complexes have been also carried out which give symmetrical tetradentate Schiff base complexes. These complexes were characterized by a combination of elemental analysis, IR, magnetic susceptibility measurements, 1H, 13C NMR and electronic spectral analysis methods. The spectral data were utilized to compute the important ligand field parameters B, beta and Dq. Electronic spectra show all complexes are octahedral. The B-values suggest a strong covalency in the metal-ligand sigma-bond and the Dq-values indicate a medium-strong ligand field. The stereochemistry and the nature of the complexes are markedly dependent upon the molar ratios of the reactants, the pH of the system and the nature of the anions involved. The ligands behave as bi-(0,0) and tetradentate (N2,O2) donors.

Stereochemistry of new nitrogen containing heterocyclic aldehyde. VI. Novel structural and properties models of uranyl with quinoline azodyes.

A novel series of UO2(2+) complexes with 5-(4'-derivatives phenyldiazo)-8-hydroxy-7-quinolinecarboxaldehyde (L1H-L7H), have been prepared. The composition and structure were confirmed by elemental analyses, 'HNMR spectra and IR spectroscopy measurements. Data from the above show that they exist in two isomeric solid forms. The polymeric structure results from intermolecular U=O...U=O interactions. The ligands act as a monobasic bidentate chelating agent coordinating through C=O and OH groups by replacement of a proton from the latter group. The force constant F(U-O) (mdyn A(-1)) and the bond length R(U-O) (A) of the U-O bond were calculated from the IR data and related to the electronic properties of the substituents. The existing literature on the coordination chemistry of these ligands are obscure.