Mechanism of Vinylic and Allylic Carbon−Fluorine Bond Activation of Non-Perfluorinated Olefins Using Cp*₂ZrH₂

Abstract

Cp(2)ZrH(2) (1) (Cp = pentamethylcyclopentadienyl) reacts with vinylic carbon-fluorine bonds of CF(2)=CH(2) and 1,1-difluoromethylenecyclohexane (CF(2)=C(6)H(10)) to afford Cp(2)ZrHF (2) and hydrodefluorinated products. Experimental evidence suggests that an insertion/beta-fluoride elimination mechanism is occurring. Complex 1 reacts with allylic C-F bonds of the olefins, CH(2)=CHCF(3), CH(2)=CHCF(2)CF(2)CF(2)CF(3), and CH(2)=C(CF(3))(2) to give preferentially 2 and CH(3)-CH=CF(2), CH(3)-CH=CF-CF(2)CF(2)CF(3), and CF(2)=C(CF(3))(CH(3)), respectively, by insertion/beta-fluoride elimination. In the reactions of 1 with CH(2)=CHCF(3) and CH(2)=CHCF(2)CF(2)CF(2)CF(3), both primary and secondary alkylzirconium olefin insertion intermediates were observed in the (1)H and (19)F NMR spectra at low temperature. A deuterium labeling study revealed that more than one olefin-dihydride complex is likely to exist prior to olefin insertion. In the presence of excess 1 and H(2), CH(2)=CHCF(3) and CH(2)=CHCF(2)CF(2)CF(2)CF(3) are reduced to propane and (E)-CH(3)CH(2)CF=CFCF(2)CF(3), respectively.

Influence of the Diphosphine Coordinated to Molybdenum and Tungsten Triangular M3S4 Cluster Hydrides in the Catalytic Hydrodefluorination of Pentafluoropyridine

“…In this context, lanthanides and group 4 hydrido complexes have been extensively studied for stoichiometric and catalytic HDF of aromatic, vinylic and aliphatic fluorinated substrates, although the number of catalytic versus stoichiometric transformations is still small [6][7][8][9][10][11][12][13]. Development of a catalytic process implies the challenging conversion of a stable fluorido complex into the corresponding hydrido derivative.…”

Synthese fluorierter Bausteine durch Übergangsmetall‐vermittelte Hydrodefluorierungsreaktionen

“…Angesichts der bekanntermaßen hohen Affinität früher Übergangsmetalle zu Fluoridoliganden ist es nicht verwunderlich, dass dieses Reaktionsprofil häufig bei Metallkomplexen der Gruppe 4 beobachtet wird. Aromatische, [10] vinylische [11] [12] wodurch die katalytische HDF von Pentafluorpyridin bei Raumtemperatur mçglich wird (Schema 2).…”

Catalysis and Organometallic Chemistry of Monometallic Species

“…78 Intermolecular C-H and C-F activation by group 4 complexes include computational evidence for the role of alkane adducts in selective C-H activation by titanium amido complexes 79 and activation of arene C-H bonds by cationic hafnium() silyl complexes. 80 The mechanism of C-F activation of nonperfluorinated alkenes 81 ] and C 6 F 6 have also been described. 83 New ligand systems applied to group 4 include complexes of 3a,7a,-azaborindenyl, 7 an isoelectronic analogue of indenyl, 84 and a zirconium () complex of a partially hydrogenated corranulene ('buckybowl').…”