Organonitrogen Derivatives

Carbonyl complexes with terminal amino groups are well established but not numerous because of the tendency of nitrogen to use its lone-pair electrons to bond to a second metal atom. 

Potassium salts of pyrrole, 2-acetylpyrrole, 1,2,3,4-tetrahydrocarbazole, 9-carbazole, indole, imidazole, and 1,2,4-triazole react with [Tr-CjHjFe ( 0)2 ] to form ct-N derivatives, e.g., [7r-C5H5Fe(CO)2(CT-N-pyrrolyl)] (III) (400, 421), shown to be intermediates in the formation of the n-complexes e.g., (IV) (400). Anions [M(CO)5L] (M = Cr, Mo, W) were similarly prepared from the hexacarbonyls and alkali metal derivatives of succinimide, phthalimidine, and saccharin (49). 

Chelate amino complexes (V Y = NH, Z = 0,S) were obtained from [7T-C5H5Co(CO)l2] with o-aminophenols and o-aminobenzenethiols (255). Related complexes are obtained from [Rh(CO)2Cl]2 with the latter ligands 

Treatment of [Fe(CO)4] with NaNOj or hydroxylamine under mild conditions produced a small yield of the first amino derivative [Fe(CO)j NH2]2 262-265), originally formulated incorrectly as the imino-bridged species 262), but later shown by mass spectrometry 221), and the X-ray crystal structure 158) to have an amino bridged structure (IX). The structure is characterized by a short metal-metal bond and small FeNFe and NFeN angles (Table I). Triphenylphosphine displaced one or two carbonyl groups to form the complexes [Fe2(CO)5(PPhj)(NH2)2] and [Fc2(CO)4 (PPh3)2(NH2)2], the latter undergoing oxidation with iodine to afford 

Fe3(CO)[2 reacts with o-aminobenzenethiol in boiling cyclohexane to form the nitrogen- and sulfur-bridged complex (XII), through loss of hydrogen from both the sulfur and nitrogen atoms (338). 

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Oxidation of organonitrogen compounds is an important process from both industrial and synthetic viewpoints . N-oxides are obtained by oxidation of tertiary amines (equation 52), which in some cases may undergo further reactions like Cope elimination and Meisenheimer rearrangement . The oxygenation products of secondary amines are generally hydroxylamines, nitroxides and nitrones (equation 53), while oxidation of primary amines usually afforded oxime, nitro, nitroso derivatives and azo and azoxy compounds through coupling, as shown in Scheme 17. Product composition depends on the oxidant, catalyst and reaction conditions employed. 

Hypervalent iodine(III) compounds have found wide application for the oxidation of organic derivatives of nitrogen, sulfur, selenium, tellurium and other elements. Reactions of X -iodanes with organonitrogen compounds leading to the electron-deficient nitrenium intermediates and followed by cyclizations and rearrangements (e.g., Hofmann rearrangement) are discussed in Section 3.1.13. Several other examples of oxidations at a nitrogen center are shown below in Schemes 3.168-3.170. 

Previous Reports in this series document kinetic studies on CO substitution in organosulphur-, organonitrogen-, and organophosphorus-bridged Fe2(CO)e derivatives with Lewis bases. The first two undergo bimolecular reactions while the... 

Oxidative reactions of organonitrogen species that do not involve molecular oxygen are rather limited. The only case for which the evidence is at all convincing is the oxidation of arylhydroxylamines to arylnitroso species (Table 2). This reaction resembles the first half of the hydroxylamine oxidoreductase reaction found in nitrifying bacteria. The key difference is that the aryl nitroso compound is stable (although condensation with the arylhydroxy-lamine can occur to produce the azoxy compound, ArN(O)NAr), while the inorganic analog is nitroxyl, HNO, which if released from the enzyme would rapidly dimerize and dehydrate to form N2O. Consequently, HAO does not release the HNO or NO intermediate, but instead oxidizes it to nitrite before any substrate-derived species are released. 

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