Pyrazolone complexes

Pyrazolone and its derivative are the most common ligands used for Tb(III) complexes in electroluminescence. In 1998 the first example of an electroluminescent device using a terbium pyrazolonate complex, tris(l-phenyl-3-methyl-4-isobutyl-5-pyrazolone)-bis-(triphenyl phosphine oxide) terbium [Tb(ip-PMP)3(TPPO)2] (Figure 11.20, compound 36),... 

Figure 11.20 Structures of some terbium pyrazolonate complexes.

After a systematic study of the terbium pyrazolonate complexes, we demonstrated that Tb(ip-PMP)3(TPPO)2 (compound 36) had very good electron transport properties and the recombination zone was confined mainly to the TPD layer, while Tb(ip-PMP)3(H20)(Et0H) (compound 37) showed only a hole-transport property and the recombination zone was confined mainly to the AIQ layer (Eigure 11.24). To adjust the carrier-transport properties and make the recombination zone easily confined to the terbium complex layer, we synthesized... 

The lanthanide complexes lack distinct ultraviolet-visible spectra and, hence, kinetic information on their complex formation and dissociation reactions was obtained indirectly by the metallochromic indicator method. These studies indicate that in the case of the Cyanex 272 complexes, the CPC efficiencies are mainly limited by the slow dissociation of the M(HL2)HL complex at the heptane-H20 interface. In the case of the complexes of the acylpyrazolones, the CPC efficiencies are again limited by the dissociation of the lanthanide-pyrazolone complexes at the organic-aqueous interface with the rate-limiting step being the dissociation of the ML complex. It was also shown that because the dissociation reactions are interfacial separations, efficiencies can be dramatically improved by the addition of surfactants like Triton X-100 to the organic phase and by... 

Figure 21.25 Coordination chemistry of (arene)ruthenium(II) 4-acyl-5-pyrazolonate complexes.

In mordant dyes, phenols, naphthols, and enolizable carbonyl compounds, such as pyrazolones, are generally the couplers. As a rule, 2 1 metal complexes are formed ia the afterchroming process. A typical example of a mordant dye is Eriochrome Black T (18b) which is made from the important dyestuff iatermediate nitro-l,2,4-acid, 4-amiQO-3-hydroxy-7-nitro-l-naphthalenesulfonic acid [6259-63-8]. Eriochrome Red B [3618-63-1] (49) (Cl Mordant Red 7 Cl 18760) (1, 2,4-acid — l-phenyl-3-methyl-5-pyrazolone) is another example. The equiUbrium of the two tautomeric forms depends on the nature of the solvent. 

Scheme 19 contains all the reactions observed in different examples, none being so complex (B-76MI40402). Most studies deal with the methylation of 3-methyl-1-phenyl-pyrazolone, since in this case one of the products obtained is antipyrine (2,3-dimethyl-l-phenyl-3-pyrazolin-5-one), one of the classical antipyretic agents (Section 4.04.4.1.1). 

Figure 23 Reduction by complex hydrides of pyrazolones, thiopyrazolones, iminopyrazolines and pyrazolium salts...

Solid-phase acidic dyes ai e also used in the study of the ternai y systems with pyrazolone derivatives. In addition, the colorless complex of the investigated metals with pyrazolone derivatives has been studied by means of the metal-indicator method. 

Another type of tautomerization was observed in the complexation reaction of 5-oxo tautomers of pyrazolone with metal chlorides 362 (89ZNK 2966). 

Pyrazolone, l(4-bromophenyl)-3-methyl-4-(2-methyl-6-carboxyphenylazo)-chromium complex geometrical isomerism, 6, 69 5-Pyrazolone, o-carboxyarylazo-metal complexes geometrical isomerism, 6,68... 

Pyrazolone, l-phenyl-3-methyl-4-(2-carboxyphenylazo)-chrotnium complex geometrical isomerism, 6, 68 5-Pyrazolone, l-phenyl-3-methyl-4-(2-hydroxy-4-sulfonaphth-l-ylazo)-chromium complex... 

Antipyrine (l,5-dimethyl-2-Phenyl-3-Pyrazolone) is known to form hexakis complexes with the lanthanides and yttrium salts 38). The bright green fluores-... 

The situation in the pyrazolone-azo dye series is more complex. In contrast to former assumptions the dyes are inaccurately described as azo compounds and in fact exist exclusively in a tautomeric phenylhydrazone form. The simple pyrazolone dye (116 R=H) absorbs at 398 nm in ethanol (67BCJ1239). In this instance the pyrazolone heterocyclic ring... 

A range of substituted 4-hydroxyimine-5-pyrazolone silver(I) complexes have been studied. Their properties have been reviewed.165... 

The pyrazolone derivatives (126) give intensely coloured complexes with zinc(II) ions and have been advocated as reagents for the colorimetric determination of the metal.869... 

No isomers were detected in the copper and nickel complexes of the strongly polarized o,o -dihydroxyazobenzene (89), the l-(2-hydroxyphenylazo)-2-naphthols (90), or the 1-phenyl-3-methyl-4-(2-hydroxyphenylazo)-5-pyrazolones (91). These compounds exist predominantly in the quinone hydrazone (92 and 93) and ketone hydrazone (94) forms, respectively (Section... 

Schetty related his rules only to diarylazo dyestuffs and demonstrated that o-carboxyarylazo-pyrazolones formed both facial and meridional complexes. He attributed this to the greater distance between the two oxygen donor atoms in these compounds than in the corresponding... 

Support for Schetty s postulates has been provided by X-ray crystal structure determinations. Thus the 2 1 chromium complexes (126) and (127) of the two o,o -dihydroxydiarylazo compounds 2,2 -dihydroxyazobenzene and l-(2-hydroxy-4-nitrophenylazo)-2-naphthol, respectively, have been proved89 to have meridional configurations, whilst the 2 1 chromium complex (128) of the o-carboxyarylazopyrazolone l-(4-brornophenyl)-3-methyl-4-(2-methyl-6-carboxyphenylazo)-5-pyrazolone has been proved90 to have a facial configuration. 

A similar argument can be applied to the results of later work by Idelson et al.i9 In this they prepared the chromium complex (133) by interaction of the 1 1 chromium complex of 1-phenyl-3-methyl-4-(2-hydroxy-4-cyanonaphth-l-ylazo)-5-pyrazolone and diethylenetriamine and by reaction of the azo compound with [Cr(CO)3dien]. Identical products were obtained and, since the diethylenetriamine occupies9 a facial position in [Cr(CO)3dien], it was concluded that the complex (133) had a facial configuration. Similarly, the reported77 separation of isomeric 2 1 chromium complexes of 2-amino-6-(2-hydroxy-6-nitro-4-sulfonaphth-l-ylazo)-5-naphthol-7-sulfonic acid is... 

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