Ruthenium complexes nitriles

Many ruthenium complexes with nitrile ligands also feature tertiary phosphines, but simpler complexes can be synthesized [136]... 

The structures of both these complexes, typical of ruthenium(III) nitriles, were confirmed by X-ray diffraction ruthenium(II) nitriles are also possible ... 

Primary amines at a primary carbon can be dehydrogenated to nitriles. The reaction has been carried out with a variety of reagents, among others, IF5,"9 lead tetraacetate, 20 nickel peroxide,121 NaOCl in micelles,122 S g-NiSO, 2-1 and CuCl-02-pyridine.124 Several methods have been reported for the dehydrogenation of secondary amines to imines.125 Among them126 are treatment with(l) iodosylbenzene PhIO alone or in the presence of a ruthenium complex, 27 (2) Me2SO and oxalyl chloride, 2" and (3) f-BuOOH and a rhenium catalyst. 29... 

Despite acetonitrile s feeble acidity (pATa ca 29) compared with enolizable aldehydes (67, pA s 16-17), the combination of a simple ruthenium complex, [RuCp(PPli3)2]+, and diazabicycloundecane (DBU) brings about a nitrile-selective deprotonation to give /I-hydroxynitriles (68).274 A mechanism is proposed in which DBU, aldehyde, and acetonitrile can displace triphenylphosphines, with the metal centre activating acetonitrile to convert it to an NC-CFU- ligand (proposed intermediate, 69). A nickel-diarylamidodiphosphine complex (70) also catalyses this transformation in the presence of DBU.275... 

Based on the finding that ruthenium complexes catalyzed the Michael addition of cyanoesters, Ito developed a system of RhH(CO)(PPh3)3 and chiral bi-dentated phosphine, (S,S)-(P,P)-TRAP. The catalyst promoted the asymmetric addition of 66 to 7 giving R)-67 [64, 65, 66]. In the case of a reactive acceptor, acrolein, even 0.1 mol % of the complex effectively catalyzed the reaction. An enantiomeric excess of up to 93% was attained with the diisopropylmethyl ester. Since BINAP, DIOP, CHIRAPHOS, etc., did not induce such high stereoselectivities, the frans-coordinated structure constructed by the TRAP was considered to be critical. The structure of the ruthenium complex obtained by X-ray analysis indicated the interaction of the metal with the nitrile nitrogen atom. The frans-coordinated ligand might be required to affect the remote reaction site. 

Ruthenium (III) Ruthenium(III) nitrile complexes [RuLfNHj) ] may be synthesized by reaction of L with [Ru(NH3)50H2], oxidation of [Ru(L)(NH3)j] with Ce or AgV by direct treatment of [RuCl(NH3)5] with L under reflux - or by aerial oxidation of coordinated amines. The IR spectrum of these complexes shows the C=N stretching vibration to occur at higher frequencies than in the free hgand, - indicating net n back-donation from n (L) - d/t (Ru ). This is also reflected in the reactivity of nitrile ligands coordinated to Ru . 

Ruthenium complexes of 31, 32 and 33 using the azeotrope triethylamine/formic acid as hydrogen doimor permitted the reduction of P-keto ester, amide and nitrile with high conversion (> 95%) and ee (> 90%) (Scheme 18). The electronic character and the spacer length between the polystyrene part and the benzene ring had very little effect on the reduction outcome, for a same substrate conversion and ee are similar. Here also, it has been shown that the catalyst formed with ligand 32 could be reused at least three times without loss of activity and enantioselectivity. 

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