Ruthenium complexes interactions

This conversion is catalyzed by [Ru(Hedta)(H20)] (Hedta = trianion of eth-ylenediaminetetraacetic acid) at 30 °C and 10 Pa in the presence of a solid semiconductor mixture (CdS/Pt/RuO,). The photocatalytic production of ammonia is initiated by absorption of visible light (505 nm) by the CdS semiconductor (Fig. 13.12). Presumably, the incoming photons promote electrons from the valence band (VB) of CdS to its conducting band (CB), a process that leaves holes in the valence band. Water is photooxidized by RuOi, releasing electrons which are trapped by holes in the valence band of CdS. The electrons in the conducting band are transferred to the nithenium complex via platinum metal. Protons from the water oxidation are attracted to the reduced ruthenium complex, interact with coordinated N, in some unknown fashion, and are expelled as NH3. The cycle is complete when the coordination site left by NH3 becomes occupied once again by HjO. It remains to be seen whether proposed cycles such as this one measure up to their promise. 

One other study of group 14 heteroallenes involving transition metals was reported in 1995. Jones et al. described the isolation of a ruthenium complex of a 1-silaallene (132—Scheme 32). The 1-silaallene also interacts with a hydrogen atom as well as the ruthenium metal center. Jones et al. describe this view... 

Sava, G. Alessio, E. Bergamo, A. Mestroni, G. Sulfoxide Ruthenium Complexes Non Toxic Tools for the Selective Treatment of Solid Tumor Metastases In Metallopharmaceuticals l DNA Interactions, Clarke, M. J. and Sadler, P. J., Ed. Springer-Verlag Berlin, 1999 Vol.l, pp 143-170. 

Allyl methylcarbonate reacts with norbornene following a ruthenium-catalyzed carbonylative cyclization under carbon monoxide pressure to give cyclopentenone derivatives 12 (Scheme 4).32 Catalyst loading, amine and CO pressure have been optimized to give the cyclopentenone compound in 80% yield and a total control of the stereoselectivity (exo 100%). Aromatic or bidentate amines inhibit the reaction certainly by a too strong interaction with ruthenium. A plausible mechanism is proposed. Stereoselective CM-carboruthenation of norbornene with allyl-ruthenium complex 13 followed by carbon monoxide insertion generates an acylruthenium intermediate 15. Intramolecular carboruthenation and /3-hydride elimination of 16 afford the -olefin 17. Isomerization of the double bond under experimental conditions allows formation of the cyclopentenone derivative 12. 

The chemistry of the 1 1 and 1 2 complexes differs with respect to hydrogenation (84,89). The 1 2 derivatives are inert to hydrogenation, while the 1 1 compounds are smoothly transformed into an ethylidene complex (see Scheme 1). This difference in behavior may well reflect the cause of differences in behavior of olefins on metal surfaces toward hydrogenation. The ethylidene complex may be converted back to the olefin adduct by reaction with trityl ion. The ethylidene adduct was first obtained for ruthenium by interaction of ethylene with H RujfCO) (89), and is structurally related to the corresponding cobalt derivatives, Co3(CO)9RC. As discussed above, the structure has been established in detail and involves a capping of the metal triangle... 

Acidification of the anion leads progressively to [HOs6(CO)18] and H2Os6(CO)i8. These two compounds may be compared with the related ruthenium complexes. The dihydride, H2Ru (CO)x8, was initially prepared by interaction of [Mn(CO)5] with Ru3(CO)12 (222). However, a... 

As shown earlier, A,A-dimethylaniline acts as an electron donor toward the electronically excited Ru(ll) tris(dipyridyl)complex (Bock et al. 1979). Nocera s group studied the effect of salt formation on the redox interaction between the ruthenium complex and the A/,At-dimethylaniline moiety. Two different salts, depicted in Scheme 5.26, were prepared and studied (Deng et al. 1997, Kirby et al. 1997, Roberts et al. 1997). 

An alternative route to prepare well-defined block copolymers is first to prepare the homopolymers with functional groups and then to connect them by noncovalent interactions [92-99], A systematic 4x4 library of block copolymers based on PSt and PEG connected by an asymmetrical octahedral (itXterpyridine) ruthenium complex at the block junction was reported [78], Moreover, the thin film morphology of this library was investigated. 

The stoichiometric interaction of an enyne and [RuCl(PCy3)(pcymene)]B(Ar )4 XVIIIa containing a bulky non-coordinating anion B(ArF)4 showed by NMR at —30 ° C the formation of the alkenyl alkylidene ruthenium complex and acrolein. This formation could be understood by the initial formation of a vinylidene intermediate and transfer of a hydride from the oxygen a-carbon atom to the electrophilic vinylidene carbon, as a retroene reaction step (Scheme 8.13) [54]. 

Terminal alkynes can undergo several types of interaction with ruthenium centers. In addition to the formation of ruthenium vinylidene species, a second type of activation provides alkynyl ruthenium complexes via oxidative addition. 

The possible similarity between Ru(phen)2Cl2 and etv-[Pt(NH3)2Cl2] in interactions with 2 -DNA is of much interests, since antitumor activities and toxicities of various ruthenium complexes have been recently reported. 

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