4-Acyl-5-pyrazolones

Mickler, W. Reich, A. Uhlemann, E. Extraction of iron(II) and iron(III) with 4-acyl-5-pyrazolones in comparison with long-chain l-phenyl-l,3-(cyclo) alkanediones. Sep. Sci. Technol. 1998, 33, 425-435. 

In the crystal structure of pyrazolone derivatives (Table 21, entry 8), the bond length between H2O and Sn is longer (2.42 A) and the distortion from the ideal TBP geometry (the O—Sn—O axis is bent to 174.8°) is probably due to steric hindrance of the 4-acyl-5-pyrazolonate ligand. In chloroform solution, the adduct loses the molecule of water and adopts a tetrahedral arrangement369. 

Figure 2.5 Molecular structures of l-phenyl-3-methyl-4-acyl-5-pyrazolones.

Cyclometalated Ir(III) chloro-bridged dimers [Ir(C N)(/x-Cl)]2 react with Na2C03 and various 4-acyl-5-pyrazolones (Hap) to afford [Ir(C N)(ap)] . The reaction of AgNOs with 128, NaOMe and trimeda gives 129". ... 

Mickler W, Reich A, Uhlemann E, and Bart HJ. Liquid membrane permeation of zinc, cadmium and nickel with 4-acyl-5-pyrazolones and (3-diketones. J Membr Sci 1996 119 91-97. 

Okafor synthesized fluorinated acylpyrazolones by interaction of A-substituted-5-pyrazolones and fluorinated anhydrides in pyridine.158,159 Another modified procedure starts from 4-acyl-1,2-oxazolin-5-ones, which react with substituted hydrazine affording 4-acyl-5-pyrazolones.160... 

Synthesis, structures, metal coordination chemistry and applications of 4-acyl-5-pyrazolone ligands 05CCR(249)2909. 

A limitation of jS-diketone extractants like TTA is the relatively low acidity of the extractant which requires that the aqueous pH be adjusted to above 4 for efficient extraction of the trivalent actinides and lanthanides. A class of extractants having a similar structure but greater acidity are the l-phenyl-3-methyl-4-acyl-5-pyrazolones,... 

Figure 21.24 (a) 4-Acyl-5-pyrazolones (b) [Cp M(4-acyl-5-pyrazolonate)Cl] (c) [Cp M(4-acyl-5-pyrazolonate)(MeCN)]. ... 

In conclusion to this chapter, we have to mention the coordination chemistry of half-sandwich Rh(in), Ir(III), and Ru(II) acceptors with a particular type of pyrazole-based ligands, built on the pyrazolyl fragment by inserting a carbonyl functionality in 5-position of the heterocyclic ring and an acyl moiety in 4-position, named 4-acyl-5-pyrazolones (HQ) (Fig. 21.24a) [57]. 

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

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