Groups Illb-Vb, including the lanthanides and actinides

FLUOROALKYL DERIVATIVES A. Groups Illb-Vb, including the lanthanides and actinides 

The complex formed by extraction of uranium(IV) from an acidic aqueous solution by benzoyltrifluoroacetone in carbon tetrachloride is also reported to be a useful shift reagent, the shifts induced being to lower frequency. (4) Adducts with complexes formed from uranium(IV) and other fluorinated diketones are also mentioned, but no details of shifts are given. 

The inability of normal shift reagents to complex with olefinic double bonds has been overcome by the use of a mixture of silver heptafluorobutyrate and europium or praeseodymium heptafluoro-octanedionate, the silver interacting with the olefin and the lanthanide with the carboxylate group. (5) The shifts observed are, however, rather small, as expected in view of the distance of the lanthanide from the hydrogens. 

Sixteen structures of the type [2] (X, Y = CH3 or CF3) are possible, and the thirty-two possible CF3 resonances, as well as the same number of CH3 signals, and 35 of the 36 CH signals have been identified in the spectra of solutions formed by mixing V(acac)3, V(tfacac)3 or V(hfacac)3 with the appropriate free ligand. The results agree well with isotropic shifts calculated on the basis of a model which is discussed in detail in the paper. (6) Chemical shifts for the resonances of a similar system [2] (X, Y = Ph, CF3) are also reported. 

Perfluoro(l-methylpropenyl)silver reacts readily with cyclopenta dienyldinitrosylchromium chloride in dichloromethane, to give the 

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