Ruthenium-nitroso complexes

Mechanistic studies on the reaction involving mthenium-nitrene complexes [100] or ruthenium-nitroso complexes [95] have also been reported. A stoichiometric reaction of Ru(dppe)(CO)3 (18) with ArNO gives Ru(dppe)(CO)2[CON(Ar)0] (19) (Eq. 11.51). In the first step of the catalytic reaction, nitroarene is reduced to nitrosoar-ene, while in the second step the complex 19 reacts with methanol and CO to give a... 

A single crystal X-ray crystallographic analysis established that the ruthenium nitroso complex contains a T -ArNO ligand (Ar = 5-chloro-2-... 

Miller and Meyer, 1971). The gaseous products are the same as those derived from the reaction of nitrous acid with azide ion. The reaction is kinetically first order in each reactant, and it is likely that an intermediate complex is also formed in this case. Similarly a p-nitroso complex is formed from the same ruthenium nitrosyl and N-methylaniline, possibly by initial... 

Ruthenium(II) complexes may also be used to oxidize N-Boc hydroxylamine in the presence of tert-butylhydroperoxide (TBHP) to the corresponding nitroso dieno-phile, which is subsequently trapped by cyclohexa-1,3-diene to give the hetero Diels-Alder adduct (Entry 1, Scheme 10.26) [51]. A triphenylphosphine oxide-stabilized ruthenium(IV) oxo-complex was found to be the catalytically active species. Use of a chiral bidentate bis-phosphine-derived ruthenium ligand (BINAP or PROPHOS) result in very low asymmetric induction (8 and 11%) (Entry 2, Scheme 10.26). The low level of asymmetric induction is explained by the reaction conditions (in-situ oxidation) that failed to produce discrete, stable diastereomerically pure mthenium complexes. It is shown that ruthenium(II) salen complexes also catalyze the oxidation of N-Boc-hydroxylamine in the presence of TBHP, to give the N-Boc-nitroso compound which can be efficiently trapped with a range of dienes from cyclohepta-1,3-diene (1 h, r.t., CH2CI2, 71%) to 9,10-dimethylanthracene (96 h, r.t., CH2CI2,... 

This reaction requires y-irradiation. However, the same complex (Ar = Ph) can also be obtained by reaction of PI1NO2 with Fc2(CO)9 [50]. It has also been observed that the formation of nitroso complexes from nitroarenes readily proceeds even with a ruthenium complex, provided a phenolic group is present in ortho to the nitro group (eq. 16) [53] ... 

These hydroxo-salts are all sulphur-yellow crystalline substances. The acid residues are hydrolysable and hence outside the co-ordination complex, and the aqueous solutions, unlike the hydroxo-salts of chromium-and cobalt-ammines, are neutral to litmus, a fact which Werner suggests is due to the smaller tendency of the hydroxo-radicle attached to ruthenium to combine with hydrogen ions. This tendency is much less than in the case of the ammines of cobalt and chromium, but that it still exists is indicated by the increased solubility of these hydroxo-compounds in water acidified with mineral acids, and from such solutions aquo-nitroso-tetrammino-ruthenium salts are obtained thus ... 

Several other complex nitroso derivatives of ruthenium have been prepared, namely ... 

N-nitrosation and an interesting Fischer-Hepp rearrangement to the C-nitroso isomer (Bowden et ai, 1976). Hydrazine hydrate reacts with the diarsine ruthenium complex [Ru(das)2(NO)CI]Cl2 yielding the corresponding azide complex (29) which represents another example of electrophilic nitrosation... 

A solution of 0.26 g. (1 mmole) of hydrated ruthenium trichloride in 20 ml. of ethanol is added to a stirred solution of 1.56 g. (6.0 mmoles) of triphenylphosphine in 60 ml. of boiling ethanol. Triethylamine (ca. 4 ml.) is then added dropwise until a deep-purple color develops. IV-Methyl-jV-nitroso-p-toluenesulfonamide (0.4 g.) in 20 ml. of ethanol and 6 ml. of triethylamine is added rapidly. The mixture is heated under reflux for 5 minutes, then allowed to cool. The gray precipitate is filtered, washed successively with ethanol, water, ethanol, and -hexane and dried in vacuo to give the required complex. Yield is 0.55 g. (82% based on RuC13 3H20). Anal. Calcd. for C36H30N2O2Ru C, 63.06 H, 4.41 N, 4.09 P, 9.03. Found C, 62.17 H, 4.13 N, 4.07 P, 8.26. The complex may be recrystallized from dichloromethane-methanol. 

At 220 °C and 50 atm CO, Ru3(CO)i2 is a catalyst in CH3CN for the conversion of 1 into 2 and 3 [9]. The selectivity in the synthesis of 2 was similar to the one observed with Fe(CO)s. As it is known that aromatic nitro compounds, and more easily nitroso compounds, react with Ru3(CO)i2 to give imido complexes in which the nitrogen atom is coordinated to all of the three ruthenium atoms of the cluster skeleton [10-12], the nitrene complex 4, possible intermediate in the reaction, has been synthesised (eq. 2) and its crystal and molecular structure determined [9] ... 

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