Ruthenium chelate complexes

F. E. Lyttle and D. M. Hercules 161) investigated the energetic relations in the chemiluminescent reaction of ruthenium chelate complexes (Ru-III-2.2 -bipyridyI-, — 5-methyl-1.10-phenanthrolin — and other complexes) with hydroxyl ion or hydrazide. The general reaction is... 

The chiral ruthenium chelate complexes were tested as catalysts in the reconstitutive addition reaction of 288 and 289 to give 290. In some cases the chemical yields were good however, the ee remained rather low. It has been discussed whether this is the result of a poor enantioselectivity of the catalysis or a racemization process of the product. Van der Zeijden obtained chiral diastereomeric chelates 314 and 315 in nonracemic form (66% ee) by treatment of ligand (5)-49 (66% ee) with RuCp-... 

With the exception of a few rare examples from the chemistry of molybdenum, manganese, rhenium, iron, and ruthenium, chelate complexes of O-func-tionalized cyclopentadienyl ligands have only been reported in this category for the very oxophilic group 4 metals, preferentially in their highest and most Lewis acidic oxidation state. Linked alkoxo— or aryloxo—cyclopentadienyl and ether—cyclopentadienyl systems are almost equally abundant for these metals. 

A description of the electrochemical processes occurring during ECL of these ruthenium chelate complexes, especially the (Ru(bipy)3 complexes in terms of the corresponding MO diagram has been given [21]. 

Polypyridine ruthenium (II) chelate complex [Ru (Bpy) ] is known to participate in a photoredox reaction on excitation with visible light, coupled with the... 

Ruthenium hydride complexes, e.g., the dimer 34, have been used by Hofmann et al. for the preparation of ruthenium carbene complexes [19]. Reaction of 34 with two equivalents of propargyl chloride 35 gives carbene complex 36 with a chelating diphosphane ligand (Eq. 3). Complex 36 is a remarkable example because its phosphine ligands are, in contrast to the other ruthenium carbene complexes described so far, arranged in a fixed cis stereochemistry. Although 36 was found to be less active than conventional metathesis catalysts, it catalyzes the ROMP of norbornene or cyclopentene. 

Krause R (1987) Synthesis of Ruthenium (II) Complexes of Aromatic Chelating Heterocycles Towards the Design of Luminescent Compounds. 67 1-52 Krebs B, see Klabunde T (1997) 89 177-198... 

Amphiphilic resin supported ruthenium(II) complexes similar to those displayed in structure 1 were employed as recyclable catalysts for dimethylformamide production from supercritical C02 itself [96]. Tertiary phosphines were attached to crosslinked polystyrene-poly(ethyleneglycol) graft copolymers (PS-PEG resin) with amino groups to form an immobilized chelating phosphine. In this case recycling was not particularly effective as catalytic activity declined with each subsequent cycle, probably due to oxidation of the phosphines and metal leaching. 

Fig. 15. Trends illustrating the influence of the arene, the chelate, and the leaving group on the cytotoxicity and cross-resistance of ruthenium-arene complexes developed in the Sadler lab. The complexes are not cross-resistant with cisplatin.

The addition to a double bond is observed in aromatic substrates where the reaction is assisted by chelation. The initial success of such reactions was achieved with the double alkylation of phenol with ethene (Equation (2)).1 This reaction occurs at the or/ -positions selectively by using an orthometallated ruthenium phosphate complex 1. 

Scheme 8.10 Ruthenium allenylidene complexes with chelating NHC ligand.

If the anion of 2-(2 -hydroxyphenyl)-5(4/l/)-oxazolone 336 is used as a ligand, bis-chelate complexes 337 of copper(II), nickel(II), and zinc(II) have been prepared from the corresponding metal acetates. Alternatively, 336 and 2-(2 -aminophenyl)-5(4//)-oxazolone 340 can act as ligands with metals including palladium(II), platinum(II), ruthenium(II), nickel(II), and copper(II) to produce a variety of structurally diverse complexes 338, 339, and 341 as shown in Schemes 7.109 and 7.110. ° ... 

In contrast to the chelate formation with ligand 4 the reaction of the amino-methyl ligand 3 follows another path and no chelate complex is formed. Instead two molecules of ligand 3 are P-coordinated to the Ru atom while the amino-methyl side-chains remain uncoordinated. Two diastereomeric products were observed, a meso complex 12a and a Cj-symmetric diastereomer 12b, which has two molecules of 3 with identical configurations coordinated to ruthenium (Scheme 1.5.4) [11]. 

Complex cations containing 2,2 -bipyridyl or 1,10-phenanthroline as ligands, particularly those of ruthenium, have been encountered in Section 57.3.2.2(iii). However, the bis-chelate complex was generally anchored to a polymer chain by coordination to pendant pyridyl groups although the possibility of electrochemical polymerization of a 4-vinyl-4-methyl-2,2 -bipyridyl was considered.59 In this section, some miscellaneous examples of the role of bipyridyl and phenanthroline complexes are considered. 

However, this is not to say that it is impossible to alkylate cationic complexes. The reaction of the ruthenium(n) complex [Ru(5.16)2]2+, in which only the three chelating nitrogen atoms of the 2,2 6 ,2"-terpyridine moiety are co-ordinated to the metal, with iodomethane in acetonitrile gives the alkylated product [Ru(5.17)2]4+ in near quantitative yield. 

Up to third-generation ruthenium-carbene complexed dendrimers (Fig. 6.2) prepared by Astruc et al. contain a chelating diphosphane, which is sufficiently stable for construction of the dendritic architecture while also sufficiently reactive to permit synthesis of the dendrimer depicted in Fig. 6.3 by ring-opening metathesis polymerisation (ROMP) [3]. 

Synthesis of Ruthenium(II) Complexes of Aromatic Chelating Heterocycles ... 

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