Unsaturated dodecahedranes—Synthesis of the highly pyramidalized, highly reactive C20H18 and C20H16 olefins

Melder, Johann‐Peter; Weber, Klaus; Weiler, Andreas; Sackers, Emmerich; Fritz, Hans; Hunkler, Dieter; Prinzbach, Horst

doi:10.1163/156856796x00142

Cited by 31 publications

(27 citation statements)

References 45 publications

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“…Increasingly economic routes to 5, [27] the isolation of crystalline 6 and 7 and their metal complexation, [28] the failure to isolate or to directly identify 8, 9, and 10, and the liberation of intact C 20 ions with hydrogen contents as low as C 20 H 4 through electron-impact-induced defunctionalization of increasingly higher functionalized dodecahedranes, have been the subjects of detailed publications. [21,29] Herein we present the full account [30] of the vapor-phase production and PE spectroscopic characterization of 1.…”

Section: Introductionmentioning

confidence: 99%

C₂₀ Carbon Clusters: Fullerene–Boat–Sheet Generation, Mass Selection, Photoelectron Characterization

Prinzbach

Wahl

Weiler

et al. 2006

Chemistry A European J

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Electron-impact ionization in a time-of-flight mass spectrometer of C(20)H(0-3)Br(14-12) probes-secured from C(20)H(20) dodecahedrane by a "brute-force" bromination protocol-provided bromine-free C(20)H(0-2(3)) anions in amounts that allowed the clean mass-separation of the hydrogen-free C(20) (-) ions and the photoelectron (PE) spectroscopic characterization as C(20) fullerene (electron affinity (EA)=2.25+/-0.03 eV, vibrational progressions of 730+/-70). The extremely strained C(20) fullerene ions surfaced as kinetically rather stable entities (lifetime of at least the total flight time of 0.4 ms); they only very sluggishly expel a C(2) unit. The HOMO and LUMO are suggested to be almost degenerate (DeltaE=0.27 eV). The assignment as a fullerene was corroborated by the PE characterization of the C(20) bowl (EA=2.17+/-0.03 eV, vibrational progression of 2060+/-50 cm(-1)) analogously generated from C(20)H(10) corannulene (C(20)H(1-3)Br(9-8) samples) and comparably stable. Highly resolved low-temperature PE spectra of the known C(20) ring (EA=2.49+/-0.03 eV, vibrational progressions 2022+/-45 and 455+/-30 cm(-1)), obtained from graphite, display an admixture of, most probably, a bicyclic isomer (EA=3.40+/-0.03 eV, vibrational progression 455+/-30 cm(-1)). The C(20) (+(-)) and C(20)H(2) (+(-)) cluster ions generated from polybrominated perylene (C(20)H(0-2)Br(12-10)) have (most probably) retained the planar perylene-type skeleton (sheet, EA=2.47+/-0.03 eV, vibrational progressions of 2089+/-30 and 492+/-30 cm(-1) and EA=2.18+/-0.03 eV, vibrational progressions of 2105+/-30 and 468+/-30 cm(-1)).

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Section: Introductionmentioning

confidence: 99%

C₂₀ Carbon Clusters: Fullerene–Boat–Sheet Generation, Mass Selection, Photoelectron Characterization

Prinzbach

Wahl

Weiler

et al. 2006

Chemistry A European J

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“…The stepwise introduction of double bonds into the saturated skeleton of dodecahedrane (65) has been pursued for quite some time, since Paquette et al reported the b-elimination of trifluoroacetic acid from (trifluoroacetoxy)dodecahedrane (66) induced by hydroxide and methoxide ions in an ion cyclotron resonance mass spectrometer and inferred indirectly the existence of dodecahedrene (68) in the gas phase (Scheme 13) [66]. Subsequently, Prinzbach et al systematically developed approaches to several highly strained oligodehydrododecahedranes by b-eliminations on the dodecahedrane skeleton [67].…”

Section: Generation Of C 20 -Fullerenementioning

confidence: 99%

Oligounsaturated Five‐Membered Carbocycles – Aromatic and Antiaromatic Compounds in the Same Family

Haag

Meijere

2002

Modern Arene Chemistry

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Most compounds containing oligounsaturated five-membered carbocycles ranging from cyclopentadiene to C 20 fullerene display interesting electronic and structural properties. This chapter describes recent developments in this area, starting with stabilized cyclopentadienyl cations, then discusses several fulvenes as well as spiroannelated cyclopentadiene derivatives and eventually linearly as well angularly fused oligocyclic five-membered ring systems. Among these oligounsaturated di-, tri-, and oligoquinanes, the features of the rather unstable pentalene and acepentalene are discussed with respect to their generation and electronic ground states. Structural properties, including those of the stable dilithium diides as well as several metal complexes are presented. Finally, the generation and characterization of the highly unstable C 20 fullerene, which sets a new benchmark for this class of molecules, are highlighted. 2.1

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“…With this procedure, limitations appeared when tetrabromotetrols (C 20 H 12 Br 4 (OH) 4 ) with four vicinal OH/Br groups (see Scheme 6 in reference [14]) as well as a mixture of hepta-/ octabromides (C 20 H 12.0 Br 7.8 , see Scheme 4 in reference [1]) resisted even very forcing treatment with AgOCOCF 3 , despite the attendant strain-reducing transformation into the respective polyols. Prepared by two-step hydrolysis of the corresponding diepoxide, [15] the known vicinal diol 7 [4a] and the bisvicinal 1,2,16,17-tetrol 8 described herein, served as spectral reference compounds. The tetrol in the form of ap- Figure 1.…”

Section: Introductionmentioning

confidence: 99%

“…After a surprisingly sluggish conversion, very complex mixtures of fluorinated components up to C 20 H 9 F 11 undecafluorides were generated (MS). Attempts to improve the degree of fluorination by UV irradiation or higher temperatures (Scheme 2 ii) caused mostly spontaneous, very vigorous, in some cases explosive reactions and provided only trace amounts of fluorinated C 20 entities with C 20 H 6 F 14 tetradecafluorides 15 as highest masses (m/z 512 (15) [M] + ). A "tamed", MS-controlled fluorination protocol of five stages with l,6-difluoride 13 rather than 2 as starting material, as seen with the selective transformation of C 60 into C 60 F 48 , [25] proved more rewarding.…”

Section: Introductionmentioning

confidence: 99%

Towards Perfunctionalized Dodecahedranes—En Route to C₂₀ Fullerene

Wahl

Weiler

Landenberger

et al. 2006

Chemistry A European J

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"One-pot" substitution of the twenty hydrogen atoms in pentagonal dodecahedrane (C(20)H(20)) by OH, F, Cl, and Br atoms is explored. Electrophilic insertion of oxygen atoms with DMDO and TFMDO as oxidizing reagents ended, far off the desired C(20)(OH)(20), in complex polyol mixtures (up to C(20)H(10)(OH)(10) decols, a trace of C(20)H(OH)(19)?). Perfluorination was successful in a NaF matrix but (nearly pure) C(20)F(20) could be secured only in very low yield. "Brute-force" photochlorination (heat, light, pressure, time) provided a mixture of hydrogen-free, barely soluble C(20)Cl(16) dienes in high yield and C(20)Cl(20) as a trace component. Upon electron-impact ionization of the C(20)Cl(16) material sequential loss of the chlorine atoms was the major fragmentation pathway furnishing, however, only minor amounts of chlorine-free C(20) (+) ions. "Brute-force" photobrominations delivered an extremely complex mixture of polybromides with C(20)HBr(13) trienes as the highest masses. The MS spectra exhibited exclusive loss of the Br substituents ending in rather intense singly, doubly, and triply charged C(20)H(4-0) (+(2+)(3+)) ions. The insoluble approximately C(20)HBr(13) fraction (C(20)Br(14) trienes as highest masses) obtained along a modified bromination protocol, ultimately allowed the neat mass selection of C(20) (-) ions. The C(20)Cl(16) dienes and C(20)H(0-3)Br(14-12) tri-/tetraenes, in spite of their very high olefinic pyramidalization, proved resistant to oxygen and dimerization (polymerization) but added CH(2)N(2) smoothly. Dehalogenation of the respective cycloaddition products through electron-impact ionization resulted in C(22-24)H(4-8) (+(2+)) ions possibly constituting bis-/tris-/tetrakis-methano-C(20) fullerenes or partly hydrogenated C(22), C(23), and C(24) cages.

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Unsaturated dodecahedranes—Synthesis of the highly pyramidalized, highly reactive C20H18 and C20H16 olefins

Cited by 31 publications

References 45 publications

C₂₀ Carbon Clusters: Fullerene–Boat–Sheet Generation, Mass Selection, Photoelectron Characterization

C₂₀ Carbon Clusters: Fullerene–Boat–Sheet Generation, Mass Selection, Photoelectron Characterization

Oligounsaturated Five‐Membered Carbocycles – Aromatic and Antiaromatic Compounds in the Same Family

Towards Perfunctionalized Dodecahedranes—En Route to C₂₀ Fullerene

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Unsaturated dodecahedranes—Synthesis of the highly pyramidalized, highly reactive C20H18 and C20H16 olefins

Cited by 31 publications

References 45 publications

C20 Carbon Clusters: Fullerene–Boat–Sheet Generation, Mass Selection, Photoelectron Characterization

C20 Carbon Clusters: Fullerene–Boat–Sheet Generation, Mass Selection, Photoelectron Characterization

Oligounsaturated Five‐Membered Carbocycles – Aromatic and Antiaromatic Compounds in the Same Family

Towards Perfunctionalized Dodecahedranes—En Route to C20 Fullerene

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Product

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About

C₂₀ Carbon Clusters: Fullerene–Boat–Sheet Generation, Mass Selection, Photoelectron Characterization

C₂₀ Carbon Clusters: Fullerene–Boat–Sheet Generation, Mass Selection, Photoelectron Characterization

Towards Perfunctionalized Dodecahedranes—En Route to C₂₀ Fullerene