Reactions of fluoro-olefins with octacarbonyldicobalt

Booth, Brian L.; Haszeldine, R. N.; Mitchell, Paul; Cox, J. J.

doi:10.1039/c19670000529

Cited by 11 publications

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“…Three terminal carbonyl signals were found in the 13 C{ 1 H} NMR, all appearing as multiplets, whereas the 19 F NMR spectrum displays a doublet at δ −46.6 ( 3 J FH = 17.0 Hz), a shift typical for a bridging trifluoroethylidene group. 49,50,68 Interestingly, in the presence of excess trifluoroethylene, compound As noted above, compound 13 is never obtained in an appreciable yield, even after extended periods (2 days) or upon heating (40 °C) and has only been identified by 19 F NMR spectra owing to our inability to locate its 31 P{ 1 H} and 13…”

Section: B Resultsmentioning

confidence: 93%

“…Although the majority of C–F bond activation studies have focused on the cleavage of aromatic C–F bonds, − there has been growing interest in the activation of olefinic C–F bonds. − ,,− Varying degrees of selectivity have been observed in the hydrodefluorination of fluoroolefins using metal–hydride complexes. For example, Jones et al have demonstrated the efficacy of [Cp* 2 ZrH 2 ] in the hydrodefluorination of 1,1-difluoroethylene, 1,1-difluoromethylenecyclohexane, and perfluoropropene to ethylene, methylcyclohexane, and propane, respectively, ,, while Whittlesey and co-workers have shown conversion of hexafluoropropene to mixtures of ( Z )- and ( E )-1,2,3,3,3-pentafluoropropene and 2,3,3,3-tetrafluoropropene by cis -[Ru(dmpe) 2 H 2 ] .…”

Section: Introductionmentioning

confidence: 99%

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Tandem C–F and C–H Bond Activation in Fluoroolefins Promoted by a Bis(diethylphosphino)methane-Bridged Diiridium Complex: Role of Water in the Activation Processes

et al. 2012

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The diiridium complex [Ir2(CO)3(μ-H)(depm)2]+ (1) reacts with vinyl fluoride, 1,1-difluoroethylene, trifluoroethylene, and tetrafluoroethylene, undergoing C–F bond activation in all cases, in addition to C–H activation in the incompletely substituted fluoroolefins. Reaction of 1 with vinyl fluoride readily undergoes geminal C–F/C–H activation, resulting in the bridging vinylidene product, [Ir2(H)(CO)3(μ-CCH2)(depm)2]+ (2). Compound 1 reacts with 1,1-difluoroethylene at subambient temperature to give minor amounts of [Ir2(CO)3(κ1:η2-CCH)(depm)2]+ (4), resulting from the loss of 2 equiv of HF from the fluoroolefin complex, along with a mixture of two isomers of [Ir2(C(F)CH2)(CO)3(μ-CF2CH2)(depm)2]+ (5a/5b), in which 2 equiv of the olefin has been incorporated. Compound 1 also reacts with trifluoroethylene at −30 °C, giving a 1:1 mix of isomers of the trifluoroethylene-bridged species [Ir2(H)(CO)3(μ-CFHCF2)(depm)2]+ (7a/7b), and warming this mixture above −15 °C converts both isomers to two products, [Ir2(H)(CO)3(μ-CCF2)(depm)2]+ (8), in which the geminal C–F and C–H bonds in the fluoroolefin have been activated, and [Ir2(H)(CO)3(μ-CHCF3)(depm)2]+ (9), the result of a [1,2]-fluoride shift to give the bridging 2,2,2-trifluoroethylidene moiety. Compound 9 reacts further with a second equivalent of trifluoroethylene over 12 h to produce the 2,2,2-trifluoroethylidene/cis-difluorovinyl complex, [Ir2(C(F)CFH)(CO)3(μ-CHCF3)(depm)2]+ (10). Finally, tetrafluoroethylene reacts with 1 to produce the bridged adduct, [Ir2(H)(CO)3(μ-CF2CF2)(depm)2]+ (11), followed by a single C–F activation to give [Ir2(C(F)CF2)(CO)3(depm)2]+ (12). The roles of the hydride ligand and exogenous water in the C–F activation processes are discussed.

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Section: B Resultsmentioning

confidence: 93%

Section: Introductionmentioning

confidence: 99%

Tandem C–F and C–H Bond Activation in Fluoroolefins Promoted by a Bis(diethylphosphino)methane-Bridged Diiridium Complex: Role of Water in the Activation Processes

et al. 2012

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“…4−6 Similarly, the reaction of tetrafluoroethylene with Co 2 (CO) 8 resulted in insertion into the Co−Co bond to form a binuclear perfluoroalkyl complex (OC) 4 CoCF 2 CF 2 Co(CO) 4 rather than an olefin complex. 7,8 In contrast to tetrafluoroethylene, reactions of metal carbonyls with fluorinated diolefins lead to complexes with fluorinated CC double bonds coordinated to transition metals (Figure 3). Already in 1959, Watterson and Wilkinson found the reaction of octafluoro-1,3-or 1,4-cyclohexadiene with Fe 3 (CO) 12 to give t h e m o n o n u c l e a r t e t r a h a p t o d i o l e fi n complex (η 4 -C 6 F 8 )Fe(CO) 3 , with both the CC double bonds coordinated to the same metal atom.…”

Section: Introductionmentioning

confidence: 99%

“…Initial attempts in the 1960s to exploit similar back-bonding in tetrafluoroethylene derivatives of the metal carbonyls led to interesting products but with structures not involving π-bonding of the CC double bond to the central metal atom (Figure ). Thus, the reaction of tetrafluoroethylene with Fe 3 (CO) 12 was found not to produce an olefin complex but instead the perfluorinated ferracyclopentane heterocycle C 4 F 8 Fe(CO) 4 . − Similarly, the reaction of tetrafluoroethylene with Co 2 (CO) 8 resulted in insertion into the Co–Co bond to form a binuclear perfluoroalkyl complex (OC) 4 CoCF 2 CF 2 Co(CO) 4 rather than an olefin complex. , …”

Section: Introductionmentioning

confidence: 99%

Fluorine Migration from Carbon to Iron and Fluorine–Iron Dative Bonds in Octafluorocyclohexadiene Iron Carbonyl Chemistry

Huang

et al. 2021

Organometallics

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The geometries and energies of mononuclear and binuclear octafluorocyclohexadiene iron carbonyl derivatives have been studied using density functional theory. The lowest energy C6F8Fe(CO)3 tricarbonyl structure is the octafluoro-1,3-cyclohexadiene derivative known experimentally. Isomeric structures containing the other two possible C6F8 hexagon ligands lie at higher energies. Unprecedented oxidative addition involving fluorine migration from carbon to iron is theoretically predicted in the C6F8Fe(CO)4 tetracarbonyl systems to give low-energy C6F7Fe(CO)4F structures. A similar energetically favored fluorine migration, also from carbon to iron, converts the coordinatively unsaturated (η4-C6F8)Fe(CO)2 dicarbonyl complex to the coordinatively saturated heptafluorocyclohexadienyl complex (η5-C6F7)Fe(CO)2F. For C6F8Fe2(CO)8, trans isomers with two Fe(CO)4 moieties on opposite sides of the C6F8 ring coordinated to CC bonds are the lowest energy structures. These are similar to the experimentally known hexafluorocyclopentadiene complex C5F6[Fe(CO)4]2. The corresponding cis isomers with the Fe(CO)4 moieties on the same size of the C6F8 ring are high-energy structures, possibly a consequence of the steric hindrance between the two closely spaced Fe(CO)4 moieties. The low-energy C6F8Fe2(CO)7 structures may be viewed as the substitution products of the experimentally known Fe2(CO)9, with the two carbonyl groups replaced by a terminal or bridging C6F8 ligand donating four electrons to one or both iron atoms of the central Fe2 unit. The low-energy singlet structures in the unsaturated C6F8Fe2(CO)6 system have C6F8 ligands donating electrons to the central Fe2 system not only through Fe–C bonds but also through F→Fe dative bonds involving fluorine lone pairs.

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“…Early workers, particularly Haszeldine and coworkers [7,8], also investigated the reaction of tetrafluoroethylene with Co 2 (CO) 8 . Under mild conditions the initial product is a yellow solid formulated as (OC) 4 CoCF 2 CF 2 Co(CO) 4 in which each tetrafluoroethylene carbon atom forms a -bond to the cobalt atom of a Co(CO) 4 unit ( Fig.…”

Section: Introductionmentioning

confidence: 99%

Tetrafluoroethylene versus trifluoromethylfluorocarbene complexes of cobalt carbonyl

et al. 2016

Journal of Organometallic Chemistry

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The reaction of tetrafluoroethylene with Co 2 (CO) 8 under mild conditions is reported to give (OC) 4 CoCF 2 CF 2 Co(CO) 4. This compound readily undergoes decarbonylation with accompanying fluorine migration to give the trifluoromethylfluorocarbene complex (µ-CF 3 CF)Co 2 (CO) 6 (µ-CO) and eventually the cluster CF 3 CCo 3 (CO) 9. In order to understand the chemistry of these cobalt carbonyl complexes obtained from tetrafluoroethylene, the structures and thermochemistry of the (C 2 F 4)Co 2 (CO) n (n = 8, 7, 6, 5) systems have been investigated by density functional theory. The lowest energy (C 2 F 4)Co 2 (CO) 8 isomer is the experimentally observed (OC) 4 CoCF 2 CF 2 Co(CO) 4 , lying ~6 kcal/mol in energy below the isomeric (CF 3 CF)[Co(CO) 4 ] 2. Loss of CO from (OC) 4 CoCF 2 CF 2 Co(CO) 4 with accompanying fluorine migration to give (µ-CF 3 CF)Co 2 (CO) 6 (µ-CO) is essentially thermoneutral within ~1 kcal/mol. The higher energy of ~20 kcal/mol for the isomeric (µ-CF 2 CF 2)Co 2 (CO) 6 (µ-CO) structure, where fluorine migration has not occurred, suggests a significant activation energy for this process. Further loss of CO from (µ-CF 3 CF)Co 2 (CO) 6 (µ-CO) gives low-energy (µ-CF 3 CF)Co 2 (CO) n (µ-CO) isomers (n = 5, 4) containing Co=Co multiple bonds and/or vacant coordination sites. Such structures are possible intermediates to form CF 3 CCo 3 (CO) 9 by reaction with excess Co 2 (CO) 8 followed by Co(CO) n F elimination.

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Reactions of fluoro-olefins with octacarbonyldicobalt

Cited by 11 publications

References 0 publications

Tandem C–F and C–H Bond Activation in Fluoroolefins Promoted by a Bis(diethylphosphino)methane-Bridged Diiridium Complex: Role of Water in the Activation Processes

Tandem C–F and C–H Bond Activation in Fluoroolefins Promoted by a Bis(diethylphosphino)methane-Bridged Diiridium Complex: Role of Water in the Activation Processes

Fluorine Migration from Carbon to Iron and Fluorine–Iron Dative Bonds in Octafluorocyclohexadiene Iron Carbonyl Chemistry

Tetrafluoroethylene versus trifluoromethylfluorocarbene complexes of cobalt carbonyl

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