Ruthenium complexes with nitrogen ligands

Ruthenium complexes with nitrogen-containing ligands show very interesting photochemical proper ties which can be monitored by Ru NMR. In mate rials science, solid state Ru and Ru NMR has been recently applied in characterizing the packing of ruthenium metal. This result represents the first detection of Ru NMR in a paramagnetic solid. 

Some platinum metals, especially ruthenium but also rhenium, osmium, and iridium, form luminescent complexes with nitrogen-containing ligands, e.g., 2,2 -bipyridine (bpy). These complexes may participate in redox reactions with concomitant chemiluminescence in three different ways. 

The use of cyclic voltammetry has already been mentioned in the characterizations of nickel(II) complexes with nitrogen- and phosphorus-donor ligands and of ruthenium(II) terpyridine bipyridine complexes with a phosphorus(III) ligand.Similarly, it has been used in the characterization of bis(diphenylphosphinomethyl)amino ligands and their Ni(II) and Pd(II) complexes. " A novel electrochemical sensor for detection of Dimethoate insecticide, and other similar organophosphates (OPs), based on a thin film-imprinted polymer, has been produced using electrodeposition of silver nanoparticles and electropolymerisation controlled by cyclic voltammetry scans " and more details are given later under sensors and biosensors. 

Frediani, P. Bianchi, M. Salvini, A. Guarducci, R Carluccio, L.C. Piacenti, F. (1995) Ruthenium carbonyl carboxylate complexes with nitrogen-containing ligands. 3. Catalytic activity in hydrogenation, J. Organomet. Chem., 498,187-97. 

Although the photophysical and photochemical properties of platinum complexes with nitrogen-based heterocyclic ligands has received less attention than has ruthenium (Chapter 5), some recent studies have shown that a chemistry for PtX2(L-L) similar to Ru(bpy)3 has the potential of being developed. For complexes of platinum(II), three classifications of complexes can be categorized based on the nature of their emitting states. The three types of emissive states are, n-n, dn-n (MLCT), or complexes that emit from metal-metal (M-M ) excited states. ... 

In the transition metal-catalyzed reactions described above, the addition of a small quantity of base dramatically increases the reaction rate [17-21]. A more elegant approach is to include a basic site into the catalysts, as is depicted in Scheme 20.13. Noyori and others proposed a mechanism for reactions catalyzed with these 16-electron ruthenium complexes (30) that involves a six-membered transition state (31) [48-50]. The basic nitrogen atom of the ligand abstracts the hydroxyl proton from the hydrogen donor (16) and, in a concerted manner, a hydride shift takes place from the a-position of the alcohol to ruthenium (a), re-... 

Optically active metal complexes have been recognized as excellent catalysts for the enantioselective cyclopropanation of carbenes with alkenes. Normally, diazo compounds react under metal catalysts in the dark to afford carbenoid complexes as key intermediates. Katsuki et al. have reported the ds-selective and enantioselective cyclopropanation of styrene with a-diazoacetate in the presence of optically active (R,R)-(NO + )(salen)ruthenium complex 80, supported under illumination (440 nm light or an incandescent bulb) [59]. The irradiation causes dissociation of the apical ligand ON + in 80, and thus avoids the splitting of nitrogen from the a-diazoacetate. 

Here, I focus on application of ruthenium complexes as catalysts for the cyclopropanation of olefins with diazoesters to describe their catalytic activity, stereoselectivity, and enantioselectivity together with structural analysis of intermediary carbene complexes, especially with nitrogen-based ligands including porphyrin derivatives [4,5]. 

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