Aniline complexes

However, this oxidation to carbonyl failed with the complexes of tetralin, o-chlorotoluene, 9,10-dihydrophenanthrene, and acenaphthalene [109]. The aniline complex can be oxidized to the nitrobenzene complex using H202 in CF3C02H [86] Eq. (38). This reaction parallels the analogous oxidation of aminocobaltici-nium [86, 111],... 

This complex, formerly called pyridine perchromate and now finding application as a powerful and selective oxidant, is violently explosive when dry [1], Use while moist on the day of preparation and destroy any surplus with dilute alkali [2], Preparation and use of the reagent have been detailed further [3], The analogous complexes with aniline, piperidine and quinoline may be similarly hazardous [4], The damage caused by a 1 g sample of the pyridine complex exploding during desiccation on a warm day was extensive. Desiccation of the aniline complex had to be at ice temperature to avoid violent explosion [4]. Pyridinium chlorochromate is commercially available as a safer alternative oxidant of alcohols to aldehydes [5], See Chromium trioxide Pyridine Dipyridinium dichromate See Other AMMINECHROMIUM PEROXOCOMPLEXES... 

A recent X-ray determination of the structure of the 2-benzyl phenol derivative [H2Os3(CO)9(OC6H3CH2Ph)] indicates a different bonding mode from that in Fig. 33a, with a switch in the nature of the bonding groups between bridging and terminal roles (181). Detailed analysis of the X-ray data favors the structure form in Fig. 34a, although attempts to identify chemically the diene character were not successful. This structure does throw some doubt on the nature of the related aniline complex. 

Scheme 15 could be a reaction pathway parallel to the classical reaction (equation 1), and it was postulated to explain the third order in amine observed in the reactions of FDNB and aromatic amines in benzene and in chloroform184. The K values were calculated from the absorbances of the reaction mixture extrapolated to zero reaction time, in a wavelength range in which the starting materials do not show an appreciable absorbance value. Good agreement was observed between the values of K for the FDNB/aniline complex in chloroform by U.V. and 111-NMR spectroscopy, as well as for the K obtained kinetically (based on Scheme 15) and spectroscopically. 

Both monohydrido complexes contain a cyclometalated molecule derived from the N-benzylideneaniline substrate, and the presence of the aniUne Ugand in the later complex seems to be due to some imine hydrolysis caused by adventitious water. Accordingly, this aniline complex practically disappears when carefully dried substrates and solvents are used [29]. 

In general, the literature contains fewer references to complexes formed from monofunctional amines than to those formed from ammonia itself or from multidentate amines. However, some clarification of earlier studies is to be found in recent reports, e.g. the complexes [Cd(PhNH2)X2] (X = C1 or Br), and their deuterated derivatives, have been reinvestigated and shown to be octahedral.166 This latter study clarified some of the confusion present in the earlier literature concerning these compounds. Another aniline complex, 3CdCl2-4L, has been studied and it has been shown that there are two types of octahedral environment in which the cadmium atoms are found, one comprising a CdCU unit and the other a CdCL unit.167... 

The first coordination compound of this type was the aniline complex Hg(PhNH2)2(N03)2,96 but later research revealed that up to six ligands are coordinated to Hg2(N03)2. The first X-ray crystal structure determination of this type of coordination compound was published in 1967 for Hg2(phen)(N03)2.98 In this complex one Hg atom of the Hg+—Hg+ ion is bonded to both N atoms of 1,10-phenanthroline the other Hg atom is coordinated to oxygen atoms of the nitrate ions.98 More recently X-ray structure determinations have been made with complexes of Hg2(N03)2 with either 1,4-diazine (10)99 or quinoline (11).100... 

A special example is the replacement of a nitro group on [(Tj6-nitrobenzene)FeCp]+.78,79 Reaction with O-, S-, N- and stabilized C-nucleophiles gives overall addition-elimination (equation 25). The nitroarene complexes are prepared by oxidation of the corresponding aniline complexes and are readily available.78,79... 

Reaction of the pyrrole complex 341 with acrylate gives 343 via 342, and indole ring 344 is formed by oxidation with DDQ [84], Similarly, the aniline complex 345 reacts with acrylate to afford 347 via 346 [85]. 

Aniline complexes are unique in [Os] chemistry in that //2-arene coordination competes with // -nitrogen coordination. However, rj1 -coordination becomes favored when the nitrogen is substituted. For example, the N-ethyl aniline complex 77 is isolated solely in its ring-bound form (Table 11). Without Lewis acid promotion, 77 will undergo regioselective addition of... 

In the presence of Lewis acids, N-substituted aniline complexes of [Os] also add electrophiles at C4, again at the arene face opposite to that involved in metal coordination. This reaction has been shown to be general for a broader range of Michael acceptors than may be utilized with anisole complexes of [Os]. The N-ethyl aniline complex, for example, adds Michael acceptors and acetals in yields ranging from 53-95 % (Table 13, entries 1-6) [27]. The N,N-dimethyl aniline complex (entries 7-9) also adds Michael acceptors to C4 in moderate to high yields (Table 13) and adds to the <5-carbon of an a,/ ,y,<5-un saturated ester (entry 3). 

Os(NHi)5 2+ - The Pentaammineosmium(ll) Fragment Tab. 13. Scope of electrophilic additions for N-substituted aniline complexes. 

Trifluoroacetamide may be successfully employed as a nucleophile in the synthesis of aniline complexes. The formation of aniline derivatives 14g can be realized by adding the in situ generated trifluoroacetamide anion CF3CONH to the o-chlorotoluenetricarbonyl-chromium complex 14a followed by KOH treatment (Scheme 21) [31]. 

Recently it even was possible to obtain optically active poly(aniline) complexes with a helical secondary structure using (+)- and (-)-camphor sulfonic acids [395]. 

Aniline complexes of Cofll), Ni(II), Cu(II) Bis-bipyridine-silver Bipyridine complexes of osmium and chromium... 

Handlirova and Tockstein (1980) experimented with o-phenanthroline, 2,2-dipyridyl, /7-phenylenediamine, 8-hydroxyquinoline and aniline complexes of Co(II), Ni(II), and Cu(II). They observed that some of these complexes showed catalytic activity. 

Fig. 13-6. The structures of SbCl3 and two of its aniline complexes. [Reproduced by permission from R. Hulme, D. Mullen and J. C. Scrutton, Acta Cryst., 1969, A, 25, S. 171.1...

A similar kinetic scheme with Q = A can be used to account for concentration quenching, where (AQ) = (AA), an excimer. Leonhardt and Wellerand Matoga, Okada, and Ezumi first proposed such a scheme to account for the quenching of fluorescence from aromatic hydrocarbons by IV-alkyl anilines. In addition, they observed a long-wavelength structureless emission from the excited hydrocarbon-aniline complex. The key step in the... 

Insoluble in water, somewhat soluble In ether and benzene. Diamagnetic. A corresponding aniline complex exists. 

The direct synthesis of (arene)Mo(CO)3 complexes from arene and Mo(CO)g is much more limited than for chromium (Scheme 4) [11,51]. The long reaction times at elevated temperature (e.g., ten days for (benzene)Mo(CO)3) and the high sensitivity to oxygen often results in low yields for substituted arenes. While (benzene)Mo(CO)3 (40) has been reportedly obtained in near quantitative yield, the yield was based on liberated CO rather than isolated complex [11]. In the author s laboratory, an isolated yield of 50% is more realistic for this procedure. The reaction time can be shortened by reacting Mo(CO)g in benzene in the presence of pyridine in an autoclave [52]. Toma and coworkers have described a different procedure that uses a double condenser system, and decalin plus ethylformate as solvent [53]. With a bath temperature of 240 °C this cuts the preparation time of the aniline complex 42 to 1 h (55% yield) (Scheme 4). In the authors laboratory the method is used routinely for the synthesis of complex 40 (18 h, 60% yield). 

This effect is also apparent in lithiation of aniline complexes. While the free ligand Ar,AT-dimethylaniline undergoes deprotonation selectively at the ortho... 

Azide can be used as a nucleophile, although attempts at decomplexation resulted in rearrangement of the azidobenzene and yielded a mixture of ring contraction products, cyanoferrocene and the aniline complex [73]. Hydrazine was... 

The advantage of a fluoride leaving group was clear in reaction of a hydroxy-carbamate anion with (fluorobenzene)FeCp complex, where the yield was 72% for F and 41% for Cl [79]. The (l,2-difluorobenzene)FeCp complex underwent smooth double substitution with phenethyl amine, whereas a dichloro complex led to monosubstitution. Replacement of a nitro group in q -nitrobenzene-FeCp" is possible with O, S, and N-nucleophiles [70,80,81]. The nitroarene complexes, which are not known in the Cr(CO)3 series, are prepared by oxidation of the corresponding aniline complexes. 

Table 2 Electrophilic addition reactions of r[ -aniline complexes...

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