Acetylacetone anion

CHjCOCHgCOCHj + Na 6CiiH5 Na- (Cn3( 0CHC0CHj)" + HOCjHj The acetylacetone anion is a resonance hybrid ... 

A proton is easily removed to produce the acetylacetonate anion (abbreviated acac). 

The barriers to acetyl group rotation in 84a to d are at least as high as in the acetylacetonate anion (Table 18), indicating a considerable delocalization of negative charge into Ac—Q—Ac. As mentioned later (Table 19), the twist angle in 84a is 73°. ... 

Acetylacetonate anion (acac), transition metal peroxides, 1086, 1089, 1090, 1092, 1095, 1100... 

The first example of a living polyolefin with a uniform chain length was disclosed in 1979 by Doi, Ueki and Keii 47,48) who used the soluble Ziegler-Natta catalyst composed of V(acac)3 (acac = acetylacetonate anion) and A1(C2H5)2C1 for the polymerization of propylene. In this review, we deal with the kinetics and mechanism of living coordination polymerization of a-olefins with soluble Ziegler-Natta catalysts and the synthesis of well-defined block copolymers by the use of living polyolefins. 

Doi, Ueki and Keii47,48) have found that the soluble catalyst composed of V(acac)3 (acac = acetylacetonate anion) and A1(C2H5)2C1 polymerizes propylene in toluene at —78 °C to give a syndiotactic living polypropylene having a narrow molecular weight distribution (Mw/Mn = 1.05-1.20). This low-temperature polymerization of propylene was shown to satisfy all criteria for the living polymerization 47). 

Figure 1-11. The resonance forms of some ligands that cannot be represented by a single valence bond structure (acetate anion, acetylacetonate anion and pyridine).

The mixed-ligand complex 853, containing C- and O-bound acetylacetonate anions, was isolated as a result of interaction (4.22) of palladium /h.v-(acetylacetonate) with triphenylphosphine [91] ... 

The dihalotin derivatives (Q)2SnX2 (X = F, Cl, Br and I) are probably cis octahedral in the solid state, whereas in solution they exist as a mixture of cis and trans isomers1252. It is not easily evident why a pseudo-Cs symmetry exists (or why the trans configuration is not allowed). An apparent reason is the asymmetry of the ligand, since a symmetric /3-acetylacetonate anion (acac) stabilizes the trans species (acac)2Sn(CH3)2, which has the metal on an inversion center1251. 

Acetylacetone was the first compound employed by Werner (31) as a chelating agent. He prepared four complexes of the composition, K[Pt(acac)Cl2] (acac = acetylacetonate anion, CHsCOCHCOCHs ), Pt(acac)2, K[Pt(acac)2Cl], and Na2[Pt(acac)2Cl2], and formulated their structures as follows ... 

Speciation diagrams resulting from metal-ligand titrations, with the concentration profiles of the various MLn species throughout the process of successive addition of the ligand identified. At left is the pH-dependent formation of vanadyl complexes with the acetylacetonate anion at right is the chloride ion concentration-dependent formation of chloromercury(II) species. 

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