Amine complexes of ruthenium

Examination of a series of imines of differing electronic properties showed that a change in the rate-determining step of this stoichiometric C=N hydrogenation occurs as the imine becomes more electron-rich. Hydrogenation of N-iso-propyl-(4-methyl)benzilidene amine led to an amine complex of ruthenium. In addition, the C=N hydrogenation was accompanied by isomerization of the imine to a ketimine (Eq. (47)). 

Keeping this in mind, in this paper, we have studied the kinetic details of the interaction of our chosen complex (an aqua-amine complex of ruthenium(II)) with an S-containing amino acid DL-methionine at pH 7.4 in aqueous medium and a plausible mechanism is proposed. 

Creutz C and Taube H 1973 Binuclear complexes of ruthenium amines J. Am. Chem. Soc. 95 1086... 

The course of the condensation of ethylene glycol with secondary amines (Me2NH, Et2NH, pyrrolidine or morpholine) depends on the catalyst used. Triphenylphosphine complexes of ruthenium, e.g. RuCl2(PPh3)3, give hydroxyalkylamines while hydrated ruthenium(III) chloride yields diamines (equation 24)62. 

One of the most studied ligand-metal complexes is the bis(oxazoline)-ruthe-nium(ll) complex.Kurasowa and co-workers proposed that the aqua and amine complexes of bis(oxazoline)-ruthenium(ll) 17a-d also adopt a tetrahedral geometry about the metal center. These are only a few of many examples of the complexes formed between a variety of transition metals and bis(oxazoline) ligands that have been studied. ... 

C. Che u. C. Poon, Pure Appl. Chem. 60, 1201-1204 (1988) Macrocyclic Amine Complexes of Iron, Ruthenium, and Osmium". 

A tridentate (r 6 ri1 r 1) strapped arene complex of ruthenium(II), 20, containing a pair of auxiliary nitrogen donor atoms derived from (R, R)-1,2-diphenylethylenedi-amine, has been prepared by a sequence in which the functionalized arene is first coordinated to ruthenium(II), as shown in Scheme 5.25 The structure of 20 has been... 

The rate enhancements observed in amine complexes of metal ions such as cobalt(III) and ruthenium(III) are not universally observed. Water exchange on [Fe(OH2)6l is more rapid in base ( 750-fold) (112), enhanced but less so for [Cr(OH2)6p ( 60-fold) (266), and absent in [V(OH2)6] (227). The trend reflects expectations of increasing associative character in reactions of these metal ions from Fe + to to eventually, the conjugate base may play no significant role in the exchange mechanism. For the type of complexes generally covered in this review, however, hydroxide ion causes a significant increase in lability. 

The chloride-, bromide-, and thiocyanate complexes of ruthenium(IIl) and osmium(IV) can be extracted from acid solutions by oxygen-containing solvents, also in the presence of TBP or amines [10,12-15]. Osmium has been separated from Ru after conversion into Osle and extraction with TO A [16]. From mixtures of thiocyanate complexes of Ru and Os, only the Os complex can be extracted into diethyl ether containing a small amount of peroxide [14]. Poljmrethane foam has also been used for separating Ru and Os as their thiocyanate complexes [17,18]. 

The complexes of ruthenium of the formula RUCI3L2 Where L is benzimidazole (BzlH), 2-Methylbenzimidazole (2-MebzlH), 2-Ethylbenzimidazole (2-EtbzlH) and 2-propyl benzimidazole (2-PrbzlH) acts as homogeneous catalysts in dimethylformamide in the presence of sodiumborohydride for the reduction of Schiff bases to secondary amines. The reactions were carried out at 30 C and 1 atmosphere of hydrogen pressure. Kinetic studies reveal that the reaction has depencence on [Catalyst] and [Schiff base] in the concentration ranges studied. 

Ruthenium(IIl) and Osmium(Hl) Amine and Ammine Complexes. Only a few amine complexes of Os111 are known, but for Ru111 there are several types and some of their reactions have been given in Fig. 26-F-3. Both elements form 2,2 -bipyridine and 1,10-phenanthroline complexes. 

Complexes of ruthenium and rhodium have been identified that catalyze the hydrogenation of nitriles under mild conditions with very good selectivities to the primary amine. In particular, Otsuka and co-workers showed that [RhHfP Prj) ] catalyzes the hydrogenation of a variety of nitriles to amines under mild conditions (1 atm pressure, 20 °C, 2 h Equation 15.119). The reaction is reversible primary amines undergo dehydrogenation in the presence of [Rl iHfP Prj) ] to form nitriles (Equation 15.120). Iridium catalysts for the dehydrogenation of nitriles have also been reported recently. ... 

A vast majority of the allylic substitution reactions have been reported with palladium catalysts. However, complexes of other metals also catalyze allylic substitution reactions. In particular, complexes of molybdenum,tungsten, ruthenium, rhodium, and iridium " have been shown to catalyze the reactions of a variety of carbon nucleo-pliiles. In addition, complexes of ruthenium, rhodium, and iridium catalyze the reactions of phenoxides, alkoxides, amines, and amine derivatives. " The regioselectivity of the allylic substitution process witli these metals can often complement the regioselectivity of the reactions catalyzed by palladium complexes. The regioselectivity... 

Asymmetric transfer hydrogenation can be employed in the asymmetric hydrogenation of prochiral ketones with a ruthenium complex of bis(oxazolinylmethyl) amine ligand 110. Enantioselectivities are greater than 95%.643... 

However, while ruthenium carbonyl was found to decompose the formate ion in basic media, the rate was slower (<0.1 mmol trimethyl ammonium formate to H2 and C02 per hour) than the rate of the water-gas shift reaction (>0.4 mmol H2/hr) at 5 atm CO and 100 °C. Increasing CO pressure decreased the formate decomposition rate. However, it was observed that increasing the CO pressure from 5 atm CO to 50 atm increased the H2 production rate to 10 mmol/hr. They proposed, in a similar manner to Pettit et al.,34 a mechanism that involved nucleophilic attack by amine (instead of hydroxide). Activation of the metal carbonyl (e.g., Ru3(CO) 2 cluster to Ru(CO)5) was suggested to be favored by dilution, increases in CO pressure, or, in the case of Group VIb metal carbonyl complexes, photolytic promotion. The mechanism is shown below in Scheme 9 ... 

ATH with Ruthenium Complexes of a-Picolyl Amines Linked P-Cyclodextrins 53... 

C. ATH WITH Ruthenium Complexes of a-PicoLVL Amines Linked P-Cyclodextrins... 

To support the proposed hydride transfer as shown for the substrate geranylacetone 68 in Fig. 30 proline was linked to the primary face of P-CD yielding the tertiary amine 101 which was complexed with ruthenium and employed to ATH under standard conditions. No product was formed at all which is in good agreement with observations by other groups (31,49,50). The presence of a hydrogen... 

As in the case of ruthenium, a series of tra 5-dioxoosmium(VI) complexes with macrocyclic tertiary amine ligands, trans- 0 0)2(l )f (L=14-TMC, 15-TMC, 16-TMC, CRMes), have been synthesized by the method shown in Scheme 13. ... 

The electrochemical behavior of ruthenium(IV) 0x0 complexes of tertiary amines is similar to that of polypyridyls. For the [Ru (0)(L)(0H2)] /[Ru (L)(0H)(0H2)] couples, the ring size of the macrocycle L has little effect on E°. However, replacement of a tertiary amine nitrogen by a pyridyl nitrogen leads to an increase in F°. 

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