Ruthenium complexes applications

Purcell, S. Barnett, N. Using the Agilent Cary Eclipse to measure the chemiluminescence of a ruthenium complex. Application Note, www.chem.agilent.com. 

Further improvements in activity of the ruthenium carbene complexes were achieved by incorporation of methyl groups in 3,4-position of imidazol-2-ylidene moiety. Introduction of sulfur in the trara-position to the N-heterocyclic carbene leads to increased stability of the resulting ruthenium complexes. The synthesis and the first applications of these new rathenium complexes are described herein. 

With regard to biosensor applications, a wide variety of electrochemically active species (ferrocene, ruthenium complexes, or carbon and metal (Pt, Pd, Au...) [185,186] were also introduced into the sol-gel matrices or adsorbed to improve the electron transfer from the biomolecules to the conductive support [187,188]. For instance, glucose oxidase has been trapped in organically modified sol-gel chitosan composite with adsorbed ferrocene to construct a low-cost biosensor exhibiting high sensitivity and good stability [189]. 

S. Kojima, T. Hasegawa, T. Yonemura, K. Sasaki, K. Yamamoto, Y. Makimura, T. Takahashi, T. Suzuki, Y. Susuki, and K. Kobayashi, Ruthenium complexes carrying a disialo complex-type oligosaccharide Enzymatic synthesis and its application to a luminescent probe to detect influenza viruses, Chem. Commun. (2003) 1250-1251. 

The chemistry of ruthenium has been reviewed in COMC (1982) and COMC (1995)338 339 as well as in Comprehensive Coordination Chemistry II. More recent reviews summarize the synthesis, properties, and applications of diruthenium tetracarboxylates341 as well as ruthenium catalysis in organic synthesis in general.342 Most recent developments and applications of ruthenium complexes in organic synthesis have been reviewed up to 2004.343... 

Besides the electrochemical application, the (Cp )Rh(bpy)-complex 9 can also be used to reduce cofactors with hydrogen. In a recent study it was compared with ruthenium complex 13 [RuC12(TPPTS)2]2 (TPPTS tris(w-sulfonatophenyl)-phosphine Scheme 43.5). Both complexes were used to regenerate the cofactors in the reduction of 2-heptanone to (S)-2-heptanol, catalyzed by an ADH from Thermoanaerobium brockii (TfrADH) [46, 47]. The TON for both catalysts was 18. 

Hydride ion transfer from formic acid and its salts finds widespread application in the reduction of organic substrates, but limited use has been made of the procedure under phase-transfer catalytic conditions. However in the presence of a ruthenium complex catalyst, it is possible to selectively reduce the C=C bonds of conjugated ketones with sodium formate [11], The rate of reduction is fastest with tetrahexyl-ammonium hydrogensulphate and Aliquat the complete reduction of chalcone being effected within one hour, whereas with benzyltriethylammonium chloride only ca. 15% reduction is observed after two hours under similar conditions. 

Inter- and intramolecular (cyclometallation) reactions of this type have been ob-.served, for instance, with titanium [408,505,683-685], hafnium [411], tantalum [426,686,687], tungsten [418,542], and ruthenium complexes [688], Not only carbene complexes but also imido complexes L M=NR of, e.g., zirconium [689,690], vanadium [691], tantalum [692], or tungsten [693] undergo C-H insertion with unactivated alkanes and arenes. Some illustrative examples are sketched in Figure 3.37. No applications in organic synthesis have yet been found for these mechanistically interesting processes. 

A special application of bimetallic ruthenium complexes was found in the olefin metathesis reaction vide infra) The two metal centers were closely attached to one another through /r-halide anions. The labile assembly was the key feature to the formation of highly active catalysts. 

This book is concerned with the application of ruthenium complexes as catalysts for useful organic oxidations. 

Applications of Isolated Indenylidene-Ruthenium Complexes in ROMP... 

Actually, applications of indenylidene-ruthenium complexes for alkene metathesis were reported before, at a time when the action mode of their ruthenium allenylidene precursors was not known. These complexes catalyzed a variety of RCM reactions of dienes and enynes [31, 32, 47] (see Section 8.2.2). 

In a related report, ruthenium-catalyzed enantioselective hydrogenation of 3-keto esters was utilized to prepare the crucial alcohol intermediate 36 (Scheme 14.16). The required (3-keto ester 49 was readily prepared from commercial thiophene carboxylic acid 40. Hydrogenation of 49 then led to the desired (S)-alcohol 50 in quantitative yield and 90% enantiomeric excess, catalyzed by a chiral diphosphine-ruthenium complex generated in situ. Catalyst-substrate ratios used were as low as 1/20,000, rendering this approach amenable to industrial application. Alcohol 50 was then converted to known intermediate 36 in three steps and 60% overall yield. 

In nonbiological applications, mixed ruthenium complexes of bipyridyl ligands and substituted pteridine diones have been used as components of photovoltaic cells <2002JPH167>. When fabricated into sol-gel processed titanium oxide electrodes, these complexes achieved photocurrent conversion efficiency in the range 20 8%. 

The same concept is applicable to allylic alcohols, ketones, or ketoximes. Enol acetates or ketones were successfully converted in multi-step reactions to chiral acetates in high yields and optical yields through catalysis by Candida antarctica lipase B (CALB, Novozyme 435) and a ruthenium complex. 2,6-Dimethylheptan-4-ol served as a hydrogen donor and 4-chlorophenyl acetate as an acyl donor for the conversion of the ketones (Jung, 2000a). 

While the mono-phenyl ligand, tro, is very much like trpy the tri-phenyl ligand, tsite, is quite different in its ruthenium complex. [Ru(tsite)2]2+ has a very intense lowest absorption band191-1, a somewhat higher quantum yield than [Ru(trpy)2]2+ (0.57 vs. 0.48 at 77 K), and is a room temperature emitter (lifetime about 0.2 (is). Unfortunately a room temperature quantum yield has not been reported for comparison with [Ru(bpy)3]2+. Our estimation of the quantum yield at room temperature from the reported lifetime is 0.01, a fraction of that reported for [Ru(bpy)3]2+. Thus, even in [Ru(tsite)2]2+, deactivation modes are more prominent than in [Ru(bpy)3]2+ and the above arguments are most likely applicable. 

Despite the extensive application of ruthenium complexes in DSSC, transition metal containing polymers have received relatively little attention in the fabrication of polymeric photovoltaic cells. Most of the early works on ruthenium containing polymers were focused on the light-emitting properties.58-60 Several examples of ruthenium terpyridine/bipyridine containing conjugated polymers and their photoconducting/electroluminescent properties were reported.61,62... 

Isomerization of allylic amines (11, 53-54 12, 56-57).1 The asymmetric isomerization of allylamines to enamines effected with ruthenium complexes of (R)-and (S)-l is applicable to C5-isoprenoids, even to ones with an allylic dialkylamino group at one end and an allylic O-function at the other end. Thus it can be used to... 

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