Tetrafluoroethylene complexes with

Tetrafluoroethylene Complexes with Metallacyclopropane Structures, but with Low Activation Barriers to Olefin Rotation. 

One complex with a metal—metal bond that has been added to an olefin is cobalt octacarbonyl. It reacts with tetrafluoroethylene and it seems reasonable that this is an insertion reaction but again it has not been proved. 

Jt-Allylnickel and -cobalt compounds insert perfluoroolefins. These are included here because u-alkyl complexes probably are the true reactants. Bis-(7r-2-methallyl)-Ni(II) gives an insertion followed by a reductive elimination producing a Ni(0) complex with tetrafluoroethylene and the 1,7-diene product as a ligand ... 

Tetrafluoro-l,2,3-trithiolane 189 was synthesized by the reaction of sulfur with tetrafluoroethene. At elevated temperature, tetrafluoroethylene reacts with the complex S4(Sb2Fi 1)2 with the formation of perfluoro-3,5-dimethyl-3,5-diethyl-1,2,4-trithiolane 190. ... 

Nafion is another polymer which has a complex relationship between morphological structure and transport(27j. This is an ionomer based on tetrafluoroethylene copolymerized with units which contain sulfonic acid groups on short fluorinated side chains. The morphology of this polymer is quite complicated... 

Owing to high reactivity, hydrido complexes are utilized in the synthesis of compounds which either cannot be prepared or are prepared with difficulty in a different way. For example, tetrafluoroethylene reacts with hydrido carbonyls to give CF2CF2H complexes ... 

Protonation of tetrafluoroethylene complexes LjPKCjF,) with trifluoro-acetic acid leads, as previously noted in a preliminary communication (cf, Vol. 1, p. 185), to the formation of the tetrailuoroethyl complexes LjPtX(CF3-CHF,) (L = PPh AsPh PEtgPh, PMePh, or PBu or L, = 2,2 -bipyridyl X = 0 C-CFa), but under the conditions used only the complex (2,2 -bipyridyl)PtCl(CF CHFa) was formed with hydrogen chloride. nie complexes LaPt(olefin) (L = PPh, AsPh, or PEtjPh olehn = CFjrCFCl or CF, CF CFj) all reacted readily with trifluoroacetic acid, but the solid products L8Pt(OjC CFs)(X) (X = CjHFaCl or CsHF ) could be isolated only when L = PPhj or AsPh and these were too insoluble to allow the position of protonation to be determined by n.m.r. spectroscopy. 

Tetrafluoroethylene reacts with Fe(CO)3(butadiene) by a two-step oxidative addition process to give (43). The reaction of the rhodium(i) complex Rh(acac)(cod) with hexafluorobut-2-yne results both in trimer-ization of this alkyne, and either its insertion into a y-bonded acetyl-acetonate intermediate or a concerted addition to the acetylacetonate ring, to produce (44), RhCl3,3H20 reacts with 2-methylallyl alcohol, in the presence of 4-methylpyridine (pic), probably via two insertion reactions, to... 

CFjiCFBr, CFjrCCU, CFsCFiCF, CFjCHiCFj, or (CFs) -CF CF (x = 2—4)]. Similar photochemical reactions of fluoro-olefins occur with the zero-valent (rf ) iron and ruthenium complexes rraHJ-[M(CO)3Lj] (L = phosphine or phosphite M = Fe or Ru), to give complexes of the type [M(CO)3La(fluoro-olefin)]. Thus, tetrafluoroethylene reacts with the complexes /ra -[Fe(CO)aLj] [L = (MeO)aP or (EtO)aP] to give complexes (104). Hexafluoropropene gives an analogous complex [L = (MeO)sP], while in the case of trifluoroethylene a five-membered iron heterocyclic... 

Tetrafluoroethylene reacts with octacarbonyldicobalt to give initially the cr-complex (125), which loses CO when heated in vacuo to give the fx,-... 

It is possible to perform the paired-ion determination without using a water-immiscible solvent. The ion pair formed by an anionic surfactant with many cationic dyes, including methylene blue and rhodamine 6G, is water-insoluble and, with shaking, will adsorb to the walls of the vessel. After discarding the aqueous solution, the ion pair can be washed from the walls with ethanol or methyl cellosolve and measured spectrophotometri-cally. Best results are obtained with a poly(tetrafluoroethylene) vessel (52). In a similar vein, the ion pair can be filtered out, then dissolved and measured spectrophotometrically. This was demonstrated using a cationic iron complex with a nitrocellulose membrane filter which was soluble in the 2-methoxyethanol used for the spectrophotometric measurement (53). 

In all the complexes shown in Table 9 (with one exception) the nickel atom is four-coordinated by two phosphorus atoms and by two carbon atoms in a distorted planar arrangement (24a). The plane containing the nickel and phosphorus atoms and the plane containing the nickel and the coordinated carbon atoms form a dihedral angle which varies between 4° and 27° (24b), depending on the coordinated alkene. In the [Ni(p3)(C2F4)2] complex (25) the nickel atom is five-coordinated by three phosphorus atoms of the tridentate ligand and two carbon atoms of tetrafluoroethylene. 

Cyclohexene reacts with tetrafluoroethylene and sulfur to give 4,5 -tetramethylene- 2,2,3,3-tetrafluorothiolane (2,2,3,3-tetrafluoro-octahydrobenzo[6]thiophene) (32).249 Tetrafluoroethylene and sulfur also react with benzene to give mainly perfluorothiolane, together with some 2,2,3,3-tetrafluoro-2,3,3a,7a-tetrahydrobenzo[i>]thiophene (33) and the dihydro derivative (34)250 in the presence of iodine more complex products are obtained.251... 

Indications of the occurrence of cycloaddition were first obtained from reactions of specifically deuterated allyl anions with tetrafluoroethylene. Assuming that no hydrogen/deuterium exchange occurs in the collision complex as shown for the allyl anions themselves (Dawson el al., 1979a), the results obtained (Nibbering, 1979) may be interpreted as indicating that 65% of the allyl anions react by a linear addition (51), 20% by a [2 + 2] atom cycloaddition (52) and 15% by a [2 + 3] atom cycloaddition. (53). It should be noted here that the precise mechanistic details of the losses of HF molecules from the collision complexes in eqns (51)—(53) are not known. However, in view of the nucleophilic aromatic substitution discussed in the previous section, it is quite likely that they occur in a stepwise fashion in which complexes solvated by fluoride anions play a role. 

The observations described prompted a study of the reaction between the 2-cyanoallyl anion and tetrafluoroethylene, since this system has the merit that the charge may be accommodated in the nitrile group of the reaction intermediate in the [2 + 3] atom cycloaddition (54). Elimination of two HF molecules indeed occurs, presumably in a consecutive way, although the product ions resulting from loss of one molecule of HF from the collision complex have not been observed (Dawson and Nibbering, 1980). However, reaction (54) has not yet been studied with specifically deuterated 2-cyanoallyl anions, so that at present an end-on addition process (55) cannot be excluded. 

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