Ruthenium complexes cyanides

Complex 376 can be prepared from enantiomerically pure rhenium precursor 381. The former can be deprotonated at low temperatures initiating the [2,3]-sigmatropic rearrangement to diastereomerically pure homoallylic sulfide complex 377. After S-alkylation, cyanide treatment releases the S ligand as product 379. As an extension of this work the authors showed that iron and ruthenium complexes can be used, too [219]. 

The ruthenium complex V, with three donor ligands, is also highly electrophilic, reacting with hydride, cyanide and methoxide to give the / -cyclohexadienyl-Ru(II) complexes, VI ... 

K2[Ru(CN)5 NO)], the only fully estabhshed nitrosyl cyanide ruthenium complex, is prepared by reaction of K4[Ru(CN)j] with HN03. Its Mossbauer spectrum, which shows a more positive isomer shift than K4[Ru(CN)g], is ascribed to the greater n acceptor ability of NO" compared to CN . For K4[Ru(CN)5(N02)], prepared by reaction of K2[Ru(CN)5NO] with a decrease... 

The conversion of primary alcohols and aldehydes into carboxylic acids is generally possible with all strong oxidants. Silver(II) oxide in THF/water is particularly useful as a neutral oxidant (E.J. Corey, 1968 A). The direct conversion of primary alcohols into carboxylic esters is achieved with MnOj in the presence of hydrogen cyanide and alcohols (E.J. Corey, 1968 A,D). The remarkably smooth oxidation of ethers to esters by ruthenium tetroxide has been employed quite often (D.G. Lee, 1973). Dibutyl ether affords butyl butanoate, and tetra-hydrofuran yields butyrolactone almost quantitatively. More complex educts also give acceptable yields (M.E. Wolff, 1963). 

There are a number of osmium(VI) oxo complexes containing cyanide ligand, but none have been reported for ruthenium. The ion [0s(0)2(CN)4] can be prepared by reaction of [OSO4] with aqueous KCN. The X-ray crystal structure of Cs2[Os(0)2(CN)4] (85) shows that it has trans-6ioxo groups with 0s=0 distances of 1.750 [0s(0)2(CN)4] is luminescent both in the solid state... 

Owing to the presence of the amine and cyanide ligands, known to give rise to specific donor-acceptor interaction with solvents [126-130], an interesting solvatochromic behavior is observed for these species. For complex 1 the spectral changes are dominated by amine interactions with the solvents as shown by the linear correlation of the solvent donor number [131] with the IT band maxima and with the half-wave potential of the ruthenium amine moiety. 

Dalzin (bis(allylthiocarbamido)hydrazine) forms sparingly soluble complexes (29) in which it is bonded through sulfur and nitrogen atoms (Section 10.2.7) but the bright orange-red bismuth complex can be extracted into chloroform for a spectrophotometric determination provided cyanide is present to mask copper. 1,4-Diphenylthiosemicarbazide PhNHNC(SH)NHPh can be used for the spectrophotometric determination of ruthenium after extraction of its violet-red complex into chloroform. 

Dyes such as erythrosin B [172], eosin [173-177], rose bengal [178,179], rhodamines [180-185], cresyl violet [186-191], thionine [192], chlorophyll a and b [193-198], chlorophyllin [197,199], anthracene-9-carboxylate [200,201], perylene [202,203] 8-hydroxyquinoline [204], porphyrins [205], phthalocyanines [206,207], transition metal cyanides [208,209], Ru(bpy)32+ and its analogs [83,170,210-218], cyanines [169,219-226], squaraines [55,227-230], and phe-nylfluorone [231] which have high extinction coefficients in the visible, are often employed to extend the photoresponse of the semiconductor in photoelectro-chemical systems. Visible light sensitization of platinized Ti02 photocatalyst by surface-coated polymers derivatized with ruthenium tris(bipyridyl) complex has also been attempted [232,233]. Because the singlet excited state of these dyes is short lived it becomes essential to adsorb them on the semiconductor surface with... 

Fig. 8 Photocurrent quantum efficiency of ruthenium (4 )and osmium (S) cyanide complexed Ti02 electrodes compared with that of untreated TiOz ( )...

Proton Affinities of Some Cyanide and Aromatic Diimine Complexes of Iron Ruthenium and Osmium. J. Am. Chem. Soc. 85, 904 (1963). 

An important application of oxidation of a C-H bond adjacent to a nitrogen atom is the selective oxidation of amides. This reaction proceeds in the presence of ferf-BuOOH as the oxidant and Ru(II) salts. Thus in the example of Eq. (36), the a-tert-butylperoxy amide of the isoquinoline was obtained, which is an important synthetic intermediate for natural products [138]. This product can be conveniently reacted with a nucleophile in the presence of a Lewis add. Direct trapping of the iminium ion complex by a nudeophile was achieved in the presence of trimethylsilyl cyanide, giving a-cyanated amines as shown in Eq. (37) [45]. This ruthenium/peracid oxidation reaction provides an alternative to the Strecker reaction for the synthesis of a-amino acid derivatives since they involve the same a-cyano amine intermediates. In this way N-methyl-N-(p-methoxyphenyl) glycine could be prepared from N,N-dimethyl-p-methoxyaniline in 82% yield. 

Complexes of 82 have also been formed by the reaction of 2,6-diacetylpyridine and Af.Af-hwQ-aminopropyOamine in the presence of nickel(II) chloride and copper(II) chloride50). Other metals that have been used include copper(II) 63,64), nickel64165), cobalt(II) 66), manganese(II)73>, cobalt(I)69), eobalt(III)68,70-72), zinc(II)73>, and ruthenium(II)74). Kam and Busch 51 have reported the catalytic hydrogenation of the nickel(II) perchlorate complex of 82 to afford two nickel(II) complexes of 83 a yellow minor component and a red major component which preliminary studies indicate to be the meso form (84). The isomeric ligands can be displaced from the respective reduced complexes by cyanide ion. Ligand 84 has also been isolated and characterized as the cobalt(III) 67), iron(II)61,62), iron(III) 62>, and copper(II) complex 75,76). Dehydro — 82 has also been synthesized and complexed with nickel(II) 65,65a), and nickel(III)65 a. ... 

Ruthenium(II) Treatment of [Ru(NH3)5(OH2)]2+ or [Ru(NH3)5(acetone)]2+ with L or [RuCl(NH3)5]2+ with zinc amalgam in the presence of L yields [RuL(NH3)5]2+ (L = acetonitrile, benzonitrile,358 substituted benzonitrile,196 358 359 acrylonitrile,360 hydrogen cyanide,36,37 ethyl cyano-formate,361 dicyanamide, malononitrile, substituted malononitrile, tricyanomethanide,362 4-cyano-l-methylpyridinium196). Reaction of a hundred-fold excess of RCHO (R = Ph, Me) with [Ru(NH3)6]2+ under alkaline conditions yields [Ru(NH3)sNCR]2+.363-365 The likely mechanism of this reaction is given in Scheme 12. An alternative route to nitrile complexes is by reaction of [Ru(NH3)sOH2]2+ with aldoximes, e.g. RMeC=NOH, to afford [Ru(NH3 )5 (NCMe)]2 + and... 

---