Osmium complexes cyanides

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

Pseudohalides of Se in which the role of halogen is played by cyanide, thiocyanate or selenocyanate are known and, in the case of Se are much more stable with respect to disproportionation than are the halides themselves. Examples are Se(CN)2, Se2(CN)2, Se(SeCN)2, Se(SCN)2, Se2(SCN)2. The selenocyanate ion SeCN is ambidentate like the thiocyanate ion, etc., p. 325), being capable of ligating to metal centres via either N or Se, as in the osmium(IV) complexes [OsCl5(NCSe)], [OsCl5(SeCN)], and trans-[OsCU(NCSe)(SeCN)]2-.920) Tellurium and polonium pseudohalogen analogues include Te(CN)2 and Po(CN)4 but have been much... 

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... 

Methylbenzene halogen complex of, 3 122 iodine monochloridecomplese, 3 109 Methylchlorosilanes hydrolysis, 42 149-150, 157 pyrolysis products of, 7 356-363 Methylcobalamin, 19 151, 152 Methyl-coenzyme M reductase, 32 323-325 EPR spectra, 32 323, 325 F43 and, 32 323-324 function, 32 324-325 Methyl-CoM reductase, 32 329 Methyl cyanide, osmium carbonyl complexes, reaction, 30 198-201 Methylcyclophosphazene salts, 21 70 synthesis, 21 109... 

The one-electron reduction of NP is associated with an increase in the population of the antibonding FeNO orbital. Figure 6a shows the DFT computed LUMO of NP (58), and Fig. 6b shows the IR electrochemical response for the [OsII(CN)5NO]2 ion (59) upon one-electron reduction in acetonitrile. The spectral characterization of the osmium-nitrosyl reduced complex could be done successfully because of the inertness of the Os-L bonds (L = NO or cyanide). In contrast, NP rapidly releases a cyanide ligand upon reduction in acetonitrile (57b,57d). The strong decrease of both the vqn and v o stretching frequencies in [Osn(CN)5NO]3 is very noticeable, particularly uN(> This is as predicted from the LUMOs description, since the addition of electrons to [OsII(CN)5NO]2 must weaken the NO bond. 

Intermolecular addition of carbon nucleophiles to the ri2-pyrrolium complexes has shown limited success because of the decreased reactivity of the iminium moiety coupled with the acidity (pKa 18-20) of the ammine ligands on the osmium, the latter of which prohibits the use of robust nucleophiles. Addition of cyanide ion to the l-methyl-2//-pyr-rolium complex 32 occurs to give the 2-cyano-substituted 3-pyrroline complex 75 as one diastereomer (Figure 15). In contrast, the 1-methyl-3//-pyrrolium species 28, which possesses an acidic C-3-proton in an anti orientation, results in a significant (-30%) amount of deprotonation in addition to the 2-pyrroline complex 78 under the same reaction conditions. Uncharacteristically, 78 is isolated as a 3 2 ratio of isomers, presumably via epimerization at C-2.17 Other potential nucleophiles such as the conjugate base of malononitrile, potassium acetoacetate, and the silyl ketene acetal 2-methoxy-l-methyl-2-(trimethylsiloxy)-l-propene either do not react or result in deprotonation under ambient conditions. 

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

The wide area of osmium cluster carbonyl chemistry lies beyond the scope of this chapter (see refs. 15 and 16), though a few carbonyl complexes are covered, and of course there is full coverage of the cyanide chemistry of osmium. 

The chemistry of osmium is dominated here by the cyanide ligand there is one fulminato complex, and a number of species containing Os—Sn bonds. 

The heterobimetallic complexes [N(n-Bu)4] [Os(N)R2(/u.-0)2Cr02] catalyze the selective oxidation of alcohols with molecular oxygen. A mechanism in which alcohol coordinates to the osmium center and is oxidized by B-hydrogen elimination (see -Hydride Elimination) is consistent with the data. The hydroxide adduct of OSO4, [0s(0H)204], with ferric cyanide and other co-oxidants catalyzes the oxidative dehydrogenation of primary aromatic and aliphatic amines to nitriles, the oxidation of primary alcohols to carboxylic acids, and of secondary alcohols to ketones. Osmium derivatives such as OsCb catalyze the effective oxidation of saturated hydrocarbons in acetonitrile through a radical mechanism. ... 

Ward and coworkers [144-151] used a series of simple ruthenium(II) or osmium(II) complexes 127-136 containing cyanide and/or bpym to serve as precursors for fabrication of Ru-Ln or Os-Ln heteronuclear complexes. Reactions of these cyanide- and/or bpym-anions... 

Platinum (Pt, at. mass 195.09) occurs in its compounds in the II and IV oxidation states, compounds of Pt(IV) being the more stable. The hydroxide Pt(OH)4 dissolves in excess of NaOH. Platinum(IV) forms chloride, iodide, cyanide, and nitrite complexes. Platinum(II) and -(rV) are more difficult to reduce to the metal than is gold(ni). Zinc and aluminium in acid solution, and formaldehyde in an alkaline medium, are suitable reductants. Of the other platinum metals, palladium resembles platinum most closely, and osmium and ruthenium resemble it least. 

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