Nitrosyl complexes of ruthenium

The complex [Ru(NO)(NH3)(S4)2] has been prepared and crystallographically characterized. It contains two 84 chelating ligands, and the NO and NH3 ligands are mutually trans. This complex was the first polysulfido nitrosyl complex of ruthenium. ... 

Nitrosyl complexes of ruthenium react in a similar manner. In this case, supposedly, nucleophilic attack of the coordinated NO molecule on the benzyl halide takes place, or electrophilic addition of PhCH to the coordinated NO group occurs with concomitant addition of X to the metal ... 

The complex Ru(NH3)6] (which oxidizes in air, eq. 22.95) is made by reacting Rua3 -xH20 with Zn dust in concentrated NH3 solution. The analogous Os(ll) complex may be formed in liquid NH3, but is unstable. The reaction of HNO2 with [Ru(NH3)5] + gives the nitrosyl complex [Ru(NH3)5(NO)] in which the Ru—N—O angle is close to 180°. Numerous mononuclear nitrosyl complexes of ruthenium are known. In each of [Ru(NH3)5(NO)], ... 

Ruthenium probably forms more nitrosyl complexes [115] than any other metal. Many are octahedral Ru(NO)Xs systems, where X5 can represent a combination of neutral and anionic ligands these contain a linear (or very nearly) Ru-NO grouping and are regarded as complexes of ruthenium(II). They are often referred to as (Ru(NO) 6 systems. 

The existence of copper-nitrosyl complexes of biological significance has been briefly discussed here (Section VII). It is worth pointing out that nitrosyl complexes of other metal-containing proteins may form, and that these may be important in understanding the effects of NO on living cells. Nitrosyl complexes of many other metals are well documented (e.g., Werner and Karrer, 1918 Moeller, 1952) and include complexes of nickel, cobalt, and ruthenium. Some such complexes may be less obvious than the paramagnetic and often colorful... 

COMPLEXES OF RUTHENIUM, OSMIUM, RHODIUM, AND IRIDIUM CONTAINING HYDRIDE CARBONYL, OR NITROSYL LIGANDS... 

Besides this iron-nitrosyl complex, nitrosyl complexes of other transition metals can be used for nitrosation. As discussed by Bottomley et al. (1973, see also review by Bottomley, 1978), these complexes are not only sources of nitrosyl ions (NO" ) as two-electron acceptors, but also of nitroxide (NO ) as one-electron donor. Bottomley found that they are nitrosating reagents only if their NO stretching frequency is greater than 1886 cm The ruthenium nitrosyls are particularly interesting with respect to their reaction with aliphatic and aromatic primary amines. We discuss them in the context of metal dinitrogen complexes (Sect. 3.3). 

Pipes DW, Meyer TJ (1984) Comparisons between polypyridyl nitrosyl complexes of osmium (II) and ruthenium (II). Inorg Chem 23 2466-2472... 

Binary Compounds. The mthenium fluorides are RuF [51621 -05-7] RuF [71500-16-8] tetrameric (RuF ) [14521 -18-7] (15), and RuF [13693-087-8]. The chlorides of mthenium are RUCI2 [13465-51-5] an insoluble RuCl [10049-08-8] which exists in an a- and p-form, mthenium trichloride ttihydrate [13815-94-6], RuCl3-3H2 0, and RuCl [13465-52-6]. Commercial RuCl3-3H2 0 has a variable composition, consisting of a mixture of chloro, 0x0, hydroxo, and often nitrosyl complexes. The overall mthenium oxidation state is closer to +4 than +3. It is a water-soluble source of mthenium, and is used widely as a starting material. Ruthenium forms bromides, RuBr2 [59201-36-4] and RuBr [14014-88-1], and an iodide, Rul [13896-65-6]. 

This is the second of the common oxidation states for iron and is familiar for ruthenium, particularly with Group 15-donor ligands (Ru probably forms more nitrosyl complexes than any other metal). Osmium(II) also produces a considerable number of complexes but is usually more strongly reducing than Ru". 

For ruthenium, electrolytes based on ruthenium sulphamate or nitrosyl-sulphamate have been described, but the most useful solutions currently available are based on the anionic complex (H2 0 Cl4 Ru N Ru-Cl4-OH2) . The latter solutions operate with relatively high cathode efficiency to furnish bright deposits up to a thickness of about 0-005 0 mm, which are similar in physical characteristics to electrodeposited rhodium and have shown promise in applications for which the latter more costly metal is commonly employed. Particularly interesting is the potential application of ruthenium as an alternative to gold or rhodium plating on the contact members of sealed-reed relay switches. 

Table 1.9 summarizes structural data for a number of ruthenium nitrosyl complexes, along with IR data [121, 122],... 

For example, the substituted aniline Ar-NH2 (Ar = />-CH3OC6H4) reacts with the ruthenium nitrosyl complex Ru(bpy)2(Cl)(NO)2+ (bpy = 2,2 -bipyridine) to give a complex of the diazo ligand, namely Ru(bpy)2(Cl)(NNAr)2+ (57). Upon employing the 15N labeled nitrosyl complex Ru(bpy)2Cl(15NO)2+ this reaction resulted in the 15N coordinated product, Ru(bpy)2Cl(15NNAr)2+, demonstrating that the reaction occurs within the metal complex coordination sphere. When the reactions were conducted in non-protic solvents, these nucleophile-nitrosyl adducts could be isolated. 

Fig. 5.6 Structures of some typical ruthenium nitrosyl complexes.

Ru(CN)jNO reactions with OH , SH and SOj" resemble those of the nitroprusside ion, with attack at the coordinated nitrosyl to give analogous transients and similar second-order rate constants. Ruthenium(II) complexes of the general type Ru(N2), Nj = biden-tate hgands, are important reactants. The relative inertness of Ru(NH3) + and Ru(diimine)f+ towards substitution makes these complexes definite, although weak, outer-sphere reductants (Tables 5.4, 5.5, 5.6 and 5.1). Ruthenium(ll) complexes of the general type Ru(diimine)f +, and particularly the complex Ru(bpy)j+, have unique excited state properties. They can be used as photosensitizers in the photochemical conversion of solar energy. Scheme 8.1 ... 

Nitric oxide and iron nitrosyl complexes have been observed in the reduction of nitrite by bacterial nitrite reductases, which contain iron chlorin or iron isobac-terichlorin [151]. A specific nitric oxide reductase also exists to convert NO to nitrous oxide [9]. Iron complexes of chlorins, isobacteriochlorins, and porphyrins, as well as ruthenium and osmium polypyridines, and cobalt and nickel... 

In spite of the abundant work on this type of reactivity, no rate constants for the addition reactions had been obtained, with the exception of the [M(CN)5NO]2 ions (M = Fe,Ru,Os) (55,68), until the recently published kinetic measurements for a representative set of nitrosyl complexes MX5NO (M = mainly ruthenium) (51). Table III... 

Surprisingly, among the variable set of nucleophiles whose reactions had been studied with NP, the case of N2H4 was absent, in contrast with data available for some ruthenium-nitrosyl complexes (28). 

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