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Ruthenium(II) complexes [RuL(CO)Cl(PPh3)2], 1a–4a, have been synthesized using ligands PhN＝NC(Ar)NOH, HL 1–4, respectively, by varying the pendant aryl (Ar) groups. The single crystal X-ray diffraction studies of complexes reveal that there are certain changes in Ru–Nazo and Ru–Noxime bond lengths that may be explained primarily on the basis of electronic effects of pendant aryl groups. In 4a, all Ru–N bond lengths are longer and this is attributed to oximato–O⋯O (hydroxyphenyl) interactions. Furthermore, there are weak intramolecular F⋯π interactions in 3a. The complexes display multiple reductive responses ascribable to electron acceptance within the azo-oxime framework of the coordinated ligand and the corresponding one-electron reduced metastable anion radical complexes of type [Ru(L˙−)(CO)Cl(PPh3)2]−[1]˙− have been generated. This property of the complexes has been exploited in electron transfer catalysis via trapping of electrons in the azo-oxime skeleton in two types of reactions: (1) α-alkylation of ketones with primary alcohols and (ii) synthesis of 2-substituted quinoline derivatives from 2-aminobenzyl alcohols and substituted acetophenones/alkyl methyl ketones. The scope of catalysis has been studied and the probable catalytic pathway has been established from experimental results. The catalytic pathway is ligand-centric and redox-driven for the dehydrogenation process and the initial step involves formation of a coordinated anion radical. This leads to conversion of the starting 1° alcohol to the corresponding carbonyl via the HAT pathway, with the ruthenium(II) centre practically behaving as a template and remaining redox inactive. The catalytic reactions have been proven to be affected by the nature of pendant aryl (Ar) groups within the coordinated ligand. [ABSTRACT FROM AUTHOR]

It was first reported almost two decades ago that ligands with azo functions are capable of accepting electron(s) upon coordination to produce azo-anion radical complexes, thereby exhibiting redox non-innocence. Over the past two decades, there have been numerous reports of such complexes along with their structures and diverse characteristics. The ability of a coordinated azo function to accept one or more electron(s), thereby acting as an electron reservoir, is currently employed to carry out electron transfer catalysis since they can undergo redox transformation at mild potentials due to the presence of energetically accessible energy levels. The cooperative involvement of redox non-innocent ligand(s) containing an azo group and the coordinated metal centre can adjust and modulate the Lewis acidity of the latter through selective ligand-centred redox events, thereby manipulating the capacity of the metal centre to bind to the substrate. We have summarized the list of first row transition metal complexes of iron, cobalt, nickel, copper and zinc with redox non-innocent ligands incorporating an azo function that have been exploited as electron transfer catalysts to effectuate sustainable synthesis of a wide variety of useful chemicals. These include ketazines, pyrimidines, benzothiazole, benzoxazoles, N-acyl hydrazones, quinazoline-4(3)H-ones, C-3 alkylated indoles, N-alkylated anilines and N-alkylated heteroamines. The reaction pathways, as demonstrated by catalytic loops, reveal that the azo function of a coordinated ligand can act as an electron sink in the initial steps to bring about alcohol oxidation and thereafter, they serve as an electron pool to produce the final products either via HAT or PCET processes. [ABSTRACT FROM AUTHOR]

A study deals with the selection and pattern of trianionic symmetrical heptadentate ligands and the binding of these to vanadium. The research work presented offers an invaluable understanding of the synthetic approach in the field of mixed-valence chemistry of vanadium.

The reaction of the dihydride [Ru(super II)(H)(sub 2)(CO)(PPh3)(sub 3)] with excess azo-2,2'-bipyridine (abp) in boiling dry benzene has afforded the diradical bischelate [Ru(super II)(abp(super .-))(sub 2)(CO)(PPH3)] and the hydridic monochelate monoradical [Ru(super II)(abp(super .-))(H)(CO)(PPH3)(sub 2)]. The diradical bischelate displays strong metal-mediated antiferromagnetism, and upon oxidation to the monoradical the unpaired electron with approximately 40 percent azo pi(super star)-character gets localized in one of the chelate rings.

Research has been conducted on the reducible ligands azopyridines to investigate osmium. Isolation of nonradical congeners formed via electrochemical/chemical oxidation is discussed.

The chemical synthesis of Nickel(III) complexes of coordination type NiS2N4 using acyclic hexadentate thioether-azo-oxime ligands is described. Structural analysis is established given using single crystal X-ray spectroscopy, including selected bond distance and angle measurements. The research achieves the production of NiIII-S(thioether) species incorporating acyclic ligands for the first time.

The synthesis and characterization of saturated cyclometalated rhodium(III) thiolato complex and its spontaneous self-association in solution are described. The synthesis resulted in anti- and syn-rhodium isomers.

Copper-catalyzed multicomponent reactions with sugar, alkynes, sulfonyl azides, and amines to produce glycosylated N-sulfonylamidines are described. The reaction is shown to be general in terms of different combinations of sugar alkyne, sulfonyl azide and amines.

Objectives: Toxicity is an expression of being poisonous, indicating the state of adverse effects led by the interaction between toxicants and cells. The present study was designed to evaluate the acute oral toxicity study and 28 days repeated toxicity study of Herbal Mixture (HM) according to OECD guidelines. Materials and Methods: In acute oral toxicity study, Herbal mixture was administered at 2000mg/kg orally and animals were observed for toxic signs at 30 min, 1, 2 and 4 hr and thereafter once a day for the next 14 days. In repeated dose-28-day toxicity study, the animals were divided into four groups of 6 animals each. Group-1 animals served as a control. Group II Animals received low dose of test drug 100 mg/kg (orally). Group III animals received middle dose of test drug 200 mg/kg (orally) once daily for 28 days respectively. Group IV animals received high dose of test drug 400 mg/kg (orally) once daily for 28 days respectively. Results: The study results showed that neither the acute toxicity study of herbal mixture at the dose level of 2000mg/kg nor the repeated dose study did not produce any toxic sign or mortality during study. In repeated dose toxicity study, no significant changes were observed in the haematological and biochemical parameters, relative organ weight, gross necropsy and histopathological examination with herbal mixture treatment. Conclusion: The results of the present study suggest that LD50 of newly developed Herbal Mixture (HM)>2000mg/kg and the mixture is completely safe and non-toxic for therapy. [ABSTRACT FROM AUTHOR]

The first azo anion radical complexes of ruthenium were isolated in pure form. The relevant azo ligands and complexes were described and the reaction of 2-(arylazo)pyridines of type 1(6) with 2(7) was analyzed. It was found that ruthenium-hydrogen bond cleavage plays an important role in the formation of azo anion radicals. The isolation of azo anion radical complexes of ruthenium also provided an experimental measure of the azo anion radical nitrogen-nitrogen length.