Ruthenium pentaammine

In the simplest case of a donor-acceptor (D-A) molecule, the nonlinear optical activity arises from the electric-field-induced mixing of electronic states such as D-A and D+-A . This makes the response (polarizability) of the molecule different according to the sense of the electric field, and a second-order hyperpolarizability fi coefficient) is observed. If D and A are connected by some bridge, its role in promoting the electronic interaction will be quite similar to the bridge role in mixed-valence complexes. Metal complexes can play the role of donor or acceptor groups. Recent examples have been described with ferrocene or ruthenium(pentaammine) groups [48], but they are either monometallic or too short to be considered in this review. 

Complexes with (bpy)2(Cl)Ru bridged by 4,4 -bipyridine, or bipyridylethylene were prepared by Meyer et al., but unfortunately they exhibit lower couplings when compared to the analogous ruthenium(pentaammine) compounds [1, 67aj. This is attributed to the competitive effect of 7r-acceptor ancillary ligands which drain the electron density away from the bridging ligand [67b],... 

Figure 3. Redox-switching of (a) MLCT absorption and (b) molecular quadratic NLO response in ruthenium pentaammine complexes [33-37]...

Amides Between the Ruthenium Pentaammine Complex of Isonicotinic Acid and Glucose Oxidase Amines... 

Figure 5. Cyclic voltammograms obtained with glucose oxidase modified with -2 enzyme-bound ruthenium pentaammine pyridyl-azo functions without glucose and at 20 mM glucose concentration. 

The relay-modified enzyme electrodes vary in their chemical and electrochemical stability. In the group listed in Table 2, the enzyme with 14 of its histidines bound to ruthenium-pentaammine was both the most and the least stable. When the enzyme-bound ruthenium was predominantly in its trivalent state, the modified enzyme showed stable electrochemistry for over a week. When the ruthenium was reduced, for example by adding glucose to the solution, some of the enzyme-bound ruthenium-pentaammine complex dissociated and the glucose-concentration dependent current dropped rapidly The modified enzyme solution lost 10 % of its current in less than 5 min. Furthermore, assay of the number of bound ruthenium atoms after incubation of the modified enzyme (at 25 C and at 30 mM glucose concentration) for 20 min showed a drop from 14 ruthenium atoms/enzyme molecule to 7 ruthenium atoms/enzyme molecule. 

Ruthenium, pyrazincbis(pentaammine-electron transfer, 1,360 Ruthenium, tetraamminedichloro-cyclic voltammetry, 1,483 Ruthenium, tetraamminedihalo-cyclic voltammetry, 1,482 Ruthenium, tetrachloronitrido-tetraphenylarsenate stereochemistry, 1, 44 Ruthenium, tris(acetyIacetone)-structure, 1,65... 

Y. Harel, A. W. Adamson. Photocalorimetry. 4. Enthalpies of Substitution Reactions of Rhodium(III) and Iridium(lll) Pentaammine Halides and of Ruthenium(II) Hexaammine. J. Phys. Chem. 1986, 90, 6690-6693. 

Creutz-Taube ion [bis(pentaammine-ruthenium)pyrazine]D (30) provides an example of this. There is good reason to suppose (in spite of many earlier arguments to the contrary) that this is a fully delocalized mixed-valence system (27). In symmetry, the one-electron levels separated by energy gap 2J are calculated to have b u (bonding) and b (antibonding) symmetry,... 

Kinetic parameters k, often also and AS, occasionally AV ) for formation and dissociation of several pentacyanoferrate(II) complexes [Fe(CN)5L]" have been established. Ligands L include several S- and A-donor heterocycles,4-methyl- and 4-amino-pyridines, a series of alkylamines, 3- and 4-hydroxy- and 3- and 4-methoxy-pyridines, several amino acids, nicotinamide, " 4-pyridine aldoxime, 3-Me and 3-Ph sydnones, several bis-pyridine ligands,neutral, protonated, and methylated 4,4 -bipyridyl, 1,2-bis(4-pyridyl)ethane and traTO-l,2-bis0-pyridyl)ethene, pyrazine- 4,4 -bipyridyl- and bis(4-pyridyl)ethyne-pentaammine-cobalt(III), edta-ruthenium(III), and pentaammineruthenium-(II)and-(III) complexes of... 

PENTAAMMINE (NITROGEN)RUTHENIUM(II) SALTS AND OTHER AMMINES OF RUTHENIUM... 

Solutions of pentaammine(nitrogen)ruthenium(II) have been prepared from ruthenium (III) chloride and hydrazine hydrate.1,2 These solutions have been used to prepare pentaammine-haloruthenium(III) salts [Ru(NH3)6X]X2 (X = Cl, Br, I). [Ru(NH3)5C1]C12 has been converted to pure pentaammine-(nitrogen)ruthenium(II) salts—[Ru(NH3)5N2]X2 (X- = Cl-, Br-, I-, BF4-, PFg-)—via the reaction between azide ion and aquopentaammineruthenium(III).2 Hexaammineruthe-nium(III) salts—rRu(NH8)6]X3 (X = I-, BF4-)—have been prepared by the reaction between pentaamminechlororuthenium-(III) chloride and hydrazine monohydrochloride. 

A. SOLUTIONS CONTAINING PENTAAMMINE (NITROGEN) -RUTHENIUM(II) CATION (IMPURE PRODUCT)... 

The solution obtained as a product contains a mixture of hexa-ammineruthenium(II) and pentaammine(nitrogen)ruthenium-(II) ions. 

Pentaammine(nitrogen)ruthenium(II) salts show a strong, sharp band in the infrared spectrum in the region 2100-2169... 

Recent studies1,2 have shown the azido-pentaammineruthe-nium(III) species to be very unstable toward decomposition to pentaammine(nitrogen)ruthenium(II). Unlike [Ru(NH )s-(N3)]2+, the a s-[Ru(en)2(N )2]+ cation is moderately stable at room temperature, and its isolation is described below. Heating a s-[Ru (en) 2 (N8) 2]PF in the solid state provides a rapid and efficient preparation of cis-[Ru(en)2(N2)(Ni)]PF6. Caution. All azides are potentially explosive and should he handled with care. 

The preparation of the hexaammine complexes of ruthenium(II) and ruthenium (III) salts are sketchily described in the literature. The preparation of hexaammineruthenium(II) by the reduction of ruthenium trichloride with zinc in ammonia is described briefly by Lever and Powell.1 Allen and Senoff2 carry out the reduction using hydrazine hydrate. The hexaammineruthe-nium(III) cation is obtained by oxidation of the ruthenium(II) complex,1 and pentaamminechlororuthenium(III) dichloride is obtained by treating the former compound with hydrochloric acid.1,3 This compound may also be obtained by treating the pentaammine molecular nitrogen complex of ruthenium(II) with hydrochloric acid.2,4... 

The yellow pentaammine complex of ruthenium(III) chloride crystallizes as octahedral crystals. It is a stable compound and exists in hydrochloric acid solution over a wide range of acid concentrations. The pale yellow hexaammine complex of ruthenium(III) is soluble in water and an excellent starting material for further ruthenium(III) compounds.5... 

Table 6 lists data for binuclear mixed valence pentaammine ruthenium complexes. 

Until recently ammine complexes of osmium have been little studied compared with their ruthenium analogs. This appears to have been caused by the lack of suitable synthetic routes to them. The discovery of pentaammine(dini-trogen)osmium (II) opened convenient routes to pentaammines of osmium (III), and a convenient synthesis of hexaammineosmium(IIl)2 gave new routes to the previously unknown nitrosyls of osmium(II). Here are given the synthesis of [Os(NH3)s(N2)]l2 and its conversion to [Os(NH3)5l]l2 the synthesis of [Os(NH3)6]l3 and its conversion to [Os(NH3)5(NO)]X3 H20(X = Cl, Br, I) and the preparation of [OsX(NH3)4(NO)]2+(X = OH, Cl, Br, I) from [Os(NH3)5(NO)]3+. 

Deprotonation of a binuclear complex with (bpy)2ClRu moieties and 1,5-dipyridyl-l,3-pentadiene as bridging ligand yielded the cyanine-bridged complex, contrarily to the unsuccessful case of the bis(pentaammine)ruthenium complex (cf. (NH3)5Ru(py-) above) [14a], However, cyclic voltammetry and spectroelectro-chemical studies revealed that oxidation occurred at the cyanine bridging segment rather than on ruthenium atoms, thus precluding the preparation of a mixed-valence species. 

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