Fluoroalkyl complexes

The reaction is reversible. If a fluorinated olefin is used, it would be expected that the resulting fluoroalkyl compound would be readily obtained, since the greater strength of the metal-fluorocarbon bond as compared to the metal-hydrocarbon bond favors the insertion reaction 267). The reaction of hydroplatinum(II) complexes with fluoroolefins has been extensively studied. A surprising product from a number of these reactions is a fluorovinyl compound rather than the anticipated fluoroalkyl complex. In Fig. 4 are shown the reactions of PtHCl(PEt3)2 with a series of fluoroolefins to give PtCl(CF=CF2)(PEt3)2 (XXXIV)... 

Tp -based fluorocarbon chemistry of group 9 is in general underdeveloped, and only two reports document fluoroalkyl complexes of rhodium or iridium relevant to this discussion. However, as with cobalt, these materials do warrant separate consideration. 

Rate constants and activation parameters for the carbonyl migration reactions of fluoroacyl derivatives (13) to give six-co-ordinate fluoroalkyl complexes (14) are given in Table 2. The rates decrease in the order CFH2>CF3>CF2H, which does not... 

The insertion-P-elimination equilibrium is displaeed in the direction of the insertion for alkenes and alkynes bearing electron-withdrawing substituents. Thus, in the examples above and below, the metal-fluoroalkyl complexes are stable, even with 16 valence electrons and one p hydrogen atom. 

Diorganotin(IV) complexes 109 were characterized by NMR spectroscopy (96MI4). The downfield chemical shift of 6-H in 2-fluoroalkyl-4//-pyrido[l,2-n]pyrimidin-4-ones 111 is attributed to the anisotropic effect of the 4-carbonyl group (97JCS(P1)981). 

Fluoral has been condensed with an equivalent of chiral glycinate anion. The chirality stems from a chiral nickel complex with a chiral Schiff base derived from proline as hgand (Figure 5.17). (25, 35)-Difluorothreonine has thus been obtained with an excellent selectivity (de > 95%). This method also allows preparation of numerous fluoroalkyl and fluoroaryl analogues of threonine. Enantiopure difluorothreonine could also be prepared from ascorbic acid. ... 

Hydroxy-1,2-dicarboxylic acids, such as n- and L-a-hydroxysuccinic acid53 and D-tartaric acid.120 on treatment with sulfur tetrafluoride give complex mixtures of fluoroalkanes, fluoro-alkenes, fluoroalkyl fluorosulfites and cyclic five-membered ethers, derivatives of 2.2,5.5-tet-rafluorotetrahydrofuran. In the case of D-tartaric acid the cyclic ethers are predominant components (64%) of the reaction mixture.120 Linear and cyclic mono- and disulfites formed in these reactions give, after hydrolysis, the corresponding linear and cyclic polyfluoro alcohols and diols in high yield.53120... 

The aerial oxidation of solutions of complexes (330) has been investigated. Chromatography separation led to the identification of products which underwent dehydrogenation of the ethylene bridge (Scheme 31).2413 Such dehydrogenation reactions are inhibited by fluoroalkyl substituents and enhanced by alkyl substituents. Oxidation with hydrogen peroxide removes the ethylene bridge. 

Finally, intense ultraviolet irradiation of perfluoro(2.3-dimethylbut-2-ene) (14) yields terminal alkene 15 quantitatively.35 Unfortunately, photolysis of more complex perfluoroalkenes gives mixtures of products resulting from migration of both allylic fluorine and allylic per-fluoroalkyl groups. Perfluorobut-2-ene only undergoes geometric isomerization. Pyrolysis of 14 at temperatures up to 300 C in the dark does not lead to detectable rearrangement. 

Vicinal fluoroalkyl ethers are also obtained from olefins and methyl hypo-fluorite at low temperatures [168] and from the unstable reagents generated from additions of xenon difluoride to methanol [169] or other alcohols [170] Alcohols tend to give complex product mixtures depending on the olefin structure, and best results are often achieved when reactions are run in the presence of boron tri-fluonde Additions of xenon difluoride to trifluoromcthanesulfomc fluorosulfonic, or nitric acids give fluoroxenonium reagents that are stable to about -10 °C and... 

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