Fluorenone ketyl

SET processes do not occur among moderately electrophilic olefinic acceptors, but are likely to be involved in highly electrophilic substrates. Some recent examples are the polyadditions of cuprate to fullerenes (Sect. 10.1.1). Fluorenone ketyl radical has been detected in a cuprate reaction of fluorenone [20]. Doubly activated olefins [67-69] and bromonaphthoquinone [70] also probably react through SET. 

Similar surface-supported amides have been derived from the Sm" amide Sm N-(SiHMe)2 2(thf)x by grafting on MCM-41, MCM-48 or AS-200 further elaboration led to the formation of the corresponding Sm-fluorenone ketyl, which was shown to contain surface-confined ketyl radicals.Treatment of Sm N(SiHMe2)2 (thf)x MCM-41 with MeOH, AlHBu 2 or Si(H)Me2-substituted indene gave surface-supported catalysts for methyl methacrylate polymerisation. 

Cp )ClIr(/i-Cl)2lrCl(7] -Cp )] causes decarbonylation of sodium fluorenone ketyl in THF to yield species 302 <1998CC669, 19990M1979>. The same product is formed if treated with sodium and fluorenone in THF. Complex 302 occurs among the products of interaction of [(7] -Cp )Ir(NBu )] with aromatic pinacols. 

A particularly well-studied anion radical is the sodium 9-fluorenone ketyl radical shown in Eq. (6-14). The solvent influence on the HFS constant of the C-... 

Addition of small amounts of dipolar non-HBD solvents to solutions of the sodium 9-fluorenone ketyl radical in toluene, in which diamagnetic dimers or higher aggregates are present, gives rise to well-resolved HFS patterns. The splitting first decreases with an increase in the mole fraction of the dipolar non-HBD solvent. A limiting value is reached at mole fraction x = 0.2...0.3, due to dissociation into... 

The salt metathesis reaction of sodium fluorenone ketyl with Cp 2ZrCl2 in THF produces the corresponding zirconium fluorenone ketyl complex 856657 which was structurally characterized (Scheme 215). In the case of sodium benzophenone ketyl, further reaction between the ketyl radical and a Cp ligand takes place to give finally the ring-metallated zirconocene bis(alkoxide) complex 857. 

Fluorenone Ketyl Complexes with an Aryloxide (ArO) Ligand. .. 235... 

Fluorenone Ketyl Complexes with a C5Me5 Ligand. 237... 

Fluorenone Ketyl Complexes with an N(SiMe3)2 Ligand. 238... 

It has been found that the use of HMPA as a coordinating ligand can sufficiently suppress coupling reactions of the ketyl radicals in multi(ketyl) metal complexes to allow their isolation [5,7,15,17]. Thus, reaction of Sm metal powder with 3 equivalents of fluorenone and 3 equivalents of HMPA in THF afforded the corresponding Sm(III) tris(fluorenone ketyl) complex 11a as black-green blocks (Scheme 11) [7,17]. An X-ray analysis has shown that this complex possesses an octahedral structure, in which the central Sm atom is coordinated in mer-type fashion by three ketyls and three HMPA ligands. The similar reaction ofYb metal with 3 equivalents of fluorenone gives the Yb(III) tris(ketyl) complex lib (Scheme 11), which is isostructural and isomorphous with 11a [7]. 

In contrast with the case of fluorenone, similar reactions of Ln/HMPA (Ln= Sm, Yb) with benzophenone did not give an isolable ketyl species and yielded finally decomposition products, demonstrating again that benzophenone ketyl is more reactive than fluorenone ketyl [7]. These reactions are also in sharp con-... 

The G.F.F. theory was put to a more quantitative test by Luckhurst and OrgeF " who examined the electron spin resonance spectrum of fluorenone ketyl, generated by electrochemical reduction, in mixtures of dimethylformamide and methanol. In the range of mol fractions of methanol less than 0.15, the G.F.F. theory was able to account for the variation of all four observed splitting constants on the assumption that the alcohol and the ketyl formed a 1 1 adduct. In this region of alcohol concentrations the dimethylformamide is in excess and it is not necessary to postulate a stoichiometry for the solvation of the ketyl by dimethylformamide. At concentrations of methanol in excess of 0.15 the above description of the system was found to be inadequate, presumably because of the formation of l 2ketyl-alcohol adducts or because of a more general form of solvent effect upon the 1 1 adduct. 

Fig. 6. Temperature dependence of the alkali metal splittings in fluorenone ketyls. Uncertainties in the measurements of the splitting in each point is not greater than 0.01 mT [67Hir2].

Fig. 7. Temperature dependence of carbonyl splittings in fluorenone ketyls [67Hir2].

Fig. 10. Changes of the alkali metal splittings of fluorenone ketyls by the addition of various alcohols. The points indicate the experimental values. The curves give the predicted changes [73Nakl]. 

Fig. 12. Changes of Na splittings of Na-fluorenone ketyl by addition of DMF in THF solution at various temperatures. The points indicate the experimental values [72Wonl]. 

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