Aniline metal complexes

Tetra(o-aminophenyl)porphyrin, H-Co-Nl TPP, can for the purpose of electrochemical polymerization be simplistically viewed as four aniline molecules with a common porphyrin substituent, and one expects that their oxidation should form a "poly(aniline)" matrix with embedded porphyrin sites. The pattern of cyclic voltammetric oxidative ECP (1) of this functionalized metal complex is shown in Fig. 2A. The growing current-potential envelope represents accumulation of a polymer film that is electroactive and conducts electrons at the potentials needed to continuously oxidize fresh monomer that diffuses in from the bulk solution. If the film were not fully electroactive at this potential, since the film is a dense membrane barrier that prevents monomer from reaching the electrode, film growth would soon cease and the electrode would become passified. This was the case for the phenolically substituted porphyrin in Fig. 1. 

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. 

The coupling of Naphtol AS or its phenyl-substituted derivatives with diazonium salts from variously substituted anilines in aqueous alkaline solution (section 4-11) gave incomplete reactions and impure products in some instances, probably because these coupling components have inadequate solubility in aqueous media. Pure dyes in ca. 90% yields were obtained by reaction in dimethylformamide in the presence of sodium acetate. Metallisation of these o,o -dihydroxyazo ligands with sodium chromium salicylate or a cobalt(II) salt gave metal-complex dyes in 80-100% yields [22]. Specific structural isomers of these complexes were identified by i.r., n.m.r., Raman and UV/visible spectroscopy [23]. 

Finally, a few cyclizations of unsaturated side chains on o-halogeno-anilines or -benzenes have been catalyzed by transition metal complexes. Cyclization of the cinnamylbenzylamine (245) by palladium gives some 4-benzylisoquinoline and some of compound (246) (77TL1037). Acryloylanilines (247) and (248) can be cyclized by a nickel complex (75MI20800) or by a palladium complex (79JA5281). The mechanism for the latter reaction is given in equation (50). 

Other donors very often used in combination with fullerenes comprise ferrocene, phthalocyanine, transition metal complexes, aniline derivatives, tetrathiafulvalene and oligoacenes, carotenoids, oligoarylene, and oligothiophene and many examples are collected in recent reviews and books dedicated to this subject.3a,7e 28... 

It occurred to us that ionic interactions might be a highly suitable binding motif to enforce the formation of heterobidentate ligand combinations [48[. The assembly ligand 14 /IS has been formed from the well-known TPPMS (14, monosulfonated triphenylphosphine sodium salt) and 3-(diphcnylphosphinyl)aniline hydrochloride (IS) by a simple ion-exchange reaction (Scheme 10.6). The coordination behavior ofthe ion-pair 14 /I S has been tested with various transition metal complexes. Other... 

It has been found in the meantime that reaction (1) is generalizable (752), and that oxidative additions of this type occur for such widely differing substrates H2Y as ethylene, benzene 130), cyclic olefins, alkyl and aryl phosphines, aniline 337, 406), and H2S 130), ail of which give the same product structure with a triply-bridging Y ligand. The stability of these third-row transition metal clusters has stiU prevented catalytic reactions of these species, but it is likely that similar ones are involved in olefin and acetylene reactions catalyzed by other metal complexes. 

Aniline, A -(salicvlaldehydo)-photochromism, 718 Aniline, TV-sulfinyl-metal complexes, 804 Anils... 

Tabic 1 Rate Constants for the Bromination of Aniline, the Anilinium Ion and a Metal Complex"... 

Many stable metal complexes of arynes are known but in most of their reactions of synthetic interest, the yields are poor. For example, thermolysis of titanocene (Cp2TiPh2) at 80-100 C gives rise to a tita-nium-benzyne complex which reacts with molecular nitrogen to afford aniline with low efficiency.29 However, procedures are available for in situ generation of zirconium complexes (14) and for their coupling reactions to synthesize functionalized aromatic compounds in preparatively useful yields (Scheme I).30 Whether such complexes should be regarded as ir-bonded benzynes or o-bonded o-phenylenes, remains a debatable point.31... 

The analogy between the behaviour of these diketonate complexes and benzene derivatives is indeed remarkable, and reaction sequences very reminiscent of those observed in organic aromatic chemistry are common. In Fig. 5-9, the reduction of a nitro to an amino derivative is illustrated, a conversion reminiscent of the reduction of nitrobenzene to aniline. It is usually necessary to use kinetically inert cP or d6 metal complexes in sequences of this type. 

Organic compounds having labile hydrogen atoms, such as phenols, anilines, and acetylenes, are also oxidatively polymerized by metal-complex catalysts (Eqs. 1-3). The oxidative coupling is a dehydrogenation reaction the polymer chain produced contains the dehydrogenated monomer structure as a repeating unit. As a remarkable example, poly(phenylene ether), one of the... 

There are six principal routes available to prepare diazenido complexes and these have been reviewed before (143, 154, 275, 317), although for convenience the relevant routes will be outlined here. Other routes such as the reaction of nitrosyl complexes with an aniline (41), or the reactions of 1,3-diaryltriazenes in acid (ready cleavage to yield diazonium ions in situ) with transition metal complexes (317), are of much less general utility. 

Transition metal complexes such as Fe(CO)5, in the presence of alcohols, cause a trichloromethyl compound to be selectively reduced to the corresponding dichloromethyl compound. This reaction has been reviewed elsewhere and is a very useful means of generating a dihalomethyl group130. Also chromium(II) complexes have been used to reduce aryl bromides131,132. Aromatic compounds such as benzene, aniline and pyridine have been used as hydrogen donors for the hydrodehalogenation of a-haloketones in the presence of tin(II) and iron(II) salts133. 

Well glass plates were loaded with different phosphines, metal complexes, aniline, and 1,3-cyclohexadiene. A coloro-metric assay for unreacted aniline (a red color arising from the acid catalyzed reaction of aniline with furfural) was used to screen successfiil catalysts, that is, those that did not turn red. Catalysts derived from [Pd(7r-allyl)Cl]2 and PPhs were most active. Increasingly, such high-throughput methods are being used in catalyst discovery and optimization. 

A number of desirable properties were exhibited in this work, which include ease of monomer synthesis, mild positive electropolymerization potential, polymer stability to continuous potential cycling, and stability to storage under ambient conditions. Unfortunately, the nature of the polymer backbone could not be definitely assigned. Nevertheless, the utility of pendant phenol and aniline groups for anchoring metal complexes to an electrode surface is a method worth further investigation. 

Investigation of the catalytic activity of anilido-phosphinimine rare-earth metal complexes was exclusively reported by Cui and coworkers. Various anilido-phosphinimine rare-earth metal complexes were synthesized by deprotonation of aniline-phosphinimines II-A with [Ln(CH2SiMe3)3(THF)2] [53]. Interestingly, the deprotonation of II-A was followed by intramolecular C-H activation of the phenyl group on the phosphine moiety to generate dianionic ligands which coordinated to the metal center in a CA A -tridentate mode. The resulting complexes... 

By using type II-B aniline-phosphinimines (Scheme 20), various bisalkyl rare-earth metal complexes were synthesized. All complexes 52-58 were obtained by the reaction of the corresponding aniline-phosphinimines HL12-HL15 with [Ln(CH2SiMe3)3(THF)2] (Ln = Sc, Y, Lu) in toluene via alkyl elimination (Scheme 21) [54]. 

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