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Enolate anions solid state structures

The proportion of the /rans-O-alkylated product [101] increases in the order no ligand < 18-crown-6 < [2.2.2]-cryptand. This difference was attributed to the fact that the enolate anion in a crown-ether complex is still capable of interacting with the cation, which stabilizes conformation [96]. For the cryptate, however, cation-anion interactions are less likely and electrostatic repulsion will force the anion to adopt conformation [99], which is the same as that of the free anion in DMSO. This explanation was substantiated by the fact that the anion was found to have structure [96] in the solid state of the potassium acetoacetate complex of 18-crown-6 (Cambillau et al., 1978). Using 23Na NMR, Cornelis et al. (1978) have recently concluded that the active nucleophilic species is the ion pair formed between 18-crown-6 and sodium ethyl acetoacetate, in which Na+ is co-ordinated to both the anion and the ligand. [Pg.320]

Lithium enolates of ketones exist as aggregates in solution.29-3l,34d,35 Mixed aggregates between the enolate anion and the amide base are also possible. In 1981, Seebach and co-workers confirmed by X-ray crystallography that the lithium enolates of pinacolone and cyclopentanone form a tetrameric aggregate in the solid state, and it was assumed that a similar species exited in solution. A THF solvated tetramer of lithium pinacolonate is shown (see 33), as it was reported by Seebach. Williard et al. reported the X-ray structure of... [Pg.723]


See other pages where Enolate anions solid state structures is mentioned: [Pg.780]    [Pg.236]    [Pg.237]    [Pg.64]    [Pg.94]    [Pg.105]    [Pg.50]    [Pg.264]    [Pg.123]    [Pg.741]    [Pg.150]   
See also in sourсe #XX -- [ Pg.724 ]




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Anionic state

Anionic structures

Anions enolate structure

Enolate anions

Enolate structure

Enolates anion

Enolates anion structure

Enolates anionic

Enolic structure

Enols structure

Solid enolization

Solid state structures

Structure states

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