Isolation, characterization and some properties of free difluoroethyne, FCCF

Bürger, H.; Sommer, S.

doi:10.1039/c39910000456

Cited by 59 publications

(31 citation statements)

References 14 publications

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“…Thus, the EOM-CCSD calculation at the experimental geometry of FCCF supports the original experimental assignment of this coupling constant given in Ref. [5]. Moreover, we have also reevaluated this coupling constant from the experimental spectrum and obtained a value of 2.2 Hz.…”

Section: J(f-f) Increases (Becomes Less Negative)supporting

confidence: 85%

“…[4] The computed results prompted the authors of Ref. [2] to question the assignment of the experimental spectrum of FCCF, which yielded a value of 2.1 Hz for 3 J(F-F), [5] although the sign of this coupling constant was not determined. In an effort to resolve this discrepancy, we have reinvestigated spin-spin coupling in FCCF, with emphasis on 3 …”

Section: Introductionmentioning

confidence: 99%

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Resolving an apparent discrepancy between theory and experiment: spin–spin coupling constants for FCCF

Bene

Provasi

Alkorta

et al. 2008

Magnetic Reson in Chemistry

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Ab initio equation of motion coupled cluster singles and doubles (EOM-CCSD) and second-order polarization propagator approximation (SOPPA) calculations have been performed to evaluate spin-spin coupling constants for FCCF (difluoroethyne). The computed EOM-CCSD value of 3 J(F-F) obtained at the experimental geometry of this molecule supports the previously reported experimental value of 2.1 Hz, thereby resolving an apparent discrepancy between theory and experiment. This coupling constant exhibits a strong dependence on the C-C and C-F distances, and its small positive value results from a sensitive balance of paramagnetic spin-orbit (PSO) and spin-dipole (SD) terms. The three other unique FCCF coupling constants 1 J(C-C), 1 J(C-F), and 2 J(C-F) have also been reported and compared with experimental data. While 1 J(C-F) is in agreement with experiment, the computed value of 2 J(C-F) is larger than our estimate of the experimental coupling constant. Copyright

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Section: J(f-f) Increases (Becomes Less Negative)supporting

confidence: 85%

Section: Introductionmentioning

confidence: 99%

Resolving an apparent discrepancy between theory and experiment: spin–spin coupling constants for FCCF

Bene

Provasi

Alkorta

et al. 2008

Magnetic Reson in Chemistry

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“…[16] However, difluoroacetylene is very unstable, difficult to synthesize, and cannot be handled in quantity. The dimerization of coordinated fluorocarbyne to coordinated difluoroacetylene is therefore of interest, because it provides an entry into the coordination chemistry of difluoroacetylene without the need to synthesize and handle free difluoroacetylene.…”

Section: Introductionmentioning

confidence: 99%

The Diversity of Difluoroacetylene Coordination Modes Obtained by Coupling Fluorocarbyne Ligands on Binuclear Manganese Carbonyl Sites

Liu

Wang

et al. 2009

Chemistry A European J

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Recent work has shown that the fluorocarbyne ligand CF, isoelectronic with the NO ligand, can be generated by the defluorination of CF(3) metal complexes, as illustrated by the 2006 synthesis by Hughes et al. of [C(5)H(5)Mo(CF)(CO)(2)] in good yield by the defluorination of [C(5)H(5)Mo(CF(3))(CO)(3)]. The fluorocarbyne ligand has now been investigated as a ligand in the manganese carbonyl complexes [Mn(CF)(CO)(n)] (n = 3, 4) and [Mn(2)(CF)(2)(CO)(n)] (n = 4-7) by using density functional theory. In mononuclear complexes, such as [Mn(CF)(CO)(4)], the CF ligand behaves very much like the NO ligand in terms of pi-acceptor strength. However, in the binuclear complexes the two CF ligands couple in many of the low-energy structures to form a bridging C(2)F(2) ligand derived, at least formally, from difluoroacetylene, FC[triple bond]CF. The geometries of such [Mn(2)(C(2)F(2))(CO)(n)] complexes suggest several different bonding modes of the bridging C(2)F(2) unit. These include bonding through the orthogonal pi bonds of FC[triple bond]CF, similar to the well-known [R(2)C(2)Co(2)(CO)(6)] complexes, or bonding of the C(2)F(2) unit as a symmetrical or unsymmetrical biscarbene. This research suggests that fluorocarbyne metal chemistry can serve as a means for obtaining a variety of difluoroacetylene metal complexes, thereby avoiding the need for synthesizing and handling the very unstable difluoroacetylene.

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“…These products were also found in the thermal decomposition of acetylene 2, which suggests that the 2 31 rearrangement occurs thermally at elevated temperatures. [25] Difluoroketene 3 is a minor product in the oxidation of 1, presumably formed by a secondary reaction of 1 and CO 2 and not by the direct reaction with O 2 (Scheme 2).…”

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Oxidation of Difluorovinylidene

et al. 1998

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Difluorovinylidene is a highly reactive and extremely electrophilic singlet carbene that thermally abstracts an oxygen atom from CO 2 at temperatures as low as 30 K. The resulting difluoroketene is characterized for the first time using IR spectroscopy in combination with isotopic labeling and density functional theory (DFT) calculations. The three observed IR absorptions of the ketene at 1274, 1427, and 2162 cm À1 are assigned to the asymmetrical FCF stretching vibration and the asymmetrical and symmetrical CCO stretching vibrations, respectively. The oxidation of difluorovinylidene with 3 O 2 results in a complex product mixture with CF 2 , C 2 F 4 , CO 2 , COF 2 , and CO as the major products. A mechanism consistent with all observed products is proposed.

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Isolation, characterization and some properties of free difluoroethyne, FCCF

Cited by 59 publications

References 14 publications

Resolving an apparent discrepancy between theory and experiment: spin–spin coupling constants for FCCF

Resolving an apparent discrepancy between theory and experiment: spin–spin coupling constants for FCCF

The Diversity of Difluoroacetylene Coordination Modes Obtained by Coupling Fluorocarbyne Ligands on Binuclear Manganese Carbonyl Sites

Oxidation of Difluorovinylidene

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