Stereodynamics and Characterization of the Hexa(4‐<i>n</i>‐dodecylbiphenylyl)benzene Hexaanion that Includes a Twisted Benzene Core

Eshdat, Lior; Hoffman, Ralph E.; Fechtenkötter, Andreas; Müllen, Kläus; Rabinovitz, Mordecai

doi:10.1002/chem.200390212

Cited by 11 publications

(9 citation statements)

References 70 publications

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“…After stir ring in diethyl ether for 1 h, the color of the reaction mixture ceased to change, which is evidence that reduc tion was completed. Decantation of the resulting green solution from unconsumed lithium and removal of the solvent in vacuo afforded crystals of the tetralithium de rivative [(tms BIAN)Li 4 (Et 2 O) 3 ] 2 (5), which were charac terized by elemental analysis, 1 H, 13 C, 29 Si, and 7 Li NMR spectroscopy, and IR spectroscopy. The structure of com pound 5 was established by X ray diffraction.…”

Section: Methodsmentioning

confidence: 99%

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New acenaphthene-1,2-diimine and its reduction to the tetraanion. Molecular structures of 1,2-bis[(trimethylsilyl)imino]acenaphthene and its lithium derivatives

et al. 2006

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1,2 Bis[(trimethylsilyl)imino]acenaphthene (1) was synthesized by the reaction of acenaphthenequinone with (Me 3 Si) 2 NLi in toluene followed by treatment of the reaction product with trimethylchlorosilane. The dianionic derivative [(tms BIAN)Li 2 ] 2 (3) was ob tained as the final product by reduction of compound 1 with lithium in toluene, whereas reduction in diethyl ether afforded the tetraanion [(tms BIAN)Li 4 (Et 2 O) 3 ] 2 (5). The forma tion of the paramagnetic mono and trianions in solution was confirmed by ESR spectroscopy. Compounds 3 and 5 were isolated in the crystalline state and characterized by elemental analysis, IR spectroscopy, and NMR spectroscopy. The crystal structures of 1, 3, and 5 were established by X ray diffraction.In the last decade, acenaphthene 1,2 diimines (BIAN) have been widely used as ligands in coordination chemis try. Transition metal complexes with diimine ligands are efficient catalysts for alkyne hydrogenation, 1 carbon-car bon bond formation, 2 cycloisomerization, 3 hydrosilyla tion, 4 polymerization of alkenes 5 and acrylic mono mers, 6 and copolymerization of CO 2 and methylenecyclo propene, 7 ethylene, norbornene, 8 and styrene. 9 Acenaphthenediimine complexes of transition metals (Brookhart catalysts) are the most efficient olefin poly merization catalysts. 10 The π acceptor properties of acenaphthene 1,2 diimines in metal complexes induce an electron deficiency at the metal atom, which is re sponsible for high reactivity of these complexes toward organic compounds.Earlier, we have demonstrated that main group met als, unlike transition metals, can form complexes with different anionic forms of BIAN ligands. We used prima rily 1,2 bis[(2,6 diisopropylphenyl)imino]acenaphthene (dpp BIAN), which shows variable oxidation states in complexes with main group metals. Diimine dpp BIAN can be reduced with alkali metals in ethereal media to the mono , di , tri , and tetraanions to form the [(dpp BIAN)M n (Et 2 O) n ] salts (M = Li or Na; n = 1-4). 11In THF, alkaline earth metals reduce dpp BIAN only to the dianion to give the monomeric (dpp BIAN)M(THF) n complexes (M = Mg, Ca, Sr, or Ba; n = 2-4). 12 Reduc tion of dpp BIAN with aluminum metal in the presence of halides in toluene or Et 2 O affords the radical anionic compound (dpp BIAN)AlCl 2 and the dianionic products (dpp BIAN)AlI(Et 2 O) and (dpp BIAN)AlCl(Et 2 O), re spectively. 13 We synthesized aluminum alkyl complexes with both the radical anion and the dianion of dpp BIAN by the metathesis reactions of the corresponding so dium derivatives of dpp BIAN with alkylaluminum halides. 14 The metathesis of sodium salts of three dif ferent acenaphthene 1,2 diimines with GeCl 2 gave the germanium(II) compounds (BIAN)Ge 15 and (dpp BIAN)GeCl. 16 The (dpp BIAN)Mg(thf) 3 complex acts as a one elec tron reducing agent for organic halides 17 and aromatic ketones. 18 The reactions of (dpp BIAN)Mg(thf) 3 with compounds containing a mobile hydrogen atom, for ex ample, with aliphatic ketones, 19 nitriles, 12b or phenyl acetylene, 20 i...

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Section: Methodsmentioning

confidence: 99%

“…Unlike bis(arylimino)acenaphthenes, diimine 1 is unstable in air because, apparently, of N-Si bond hydrolysis. Compound 1 was characterized by el emental analysis, IR spectroscopy, and 1 H, 13 C, and 29 Si NMR spectroscopy. The crystal structure of 1 was established by X ray diffraction.…”

Section: Methodsmentioning

confidence: 99%

New acenaphthene-1,2-diimine and its reduction to the tetraanion. Molecular structures of 1,2-bis[(trimethylsilyl)imino]acenaphthene and its lithium derivatives

et al. 2006

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“…It should be mentioned that Rabinovitz and co‐workers determined by variable‐temperature NMR a remarkable distortion of symmetry on reduction of hexa(4‐dodecylbiphenylyl)benzene ( 32 b ) with alkali metals, which led to a twisted conformation of the central benzene ring in the hexaanion 32 b 6− (Scheme ) 78. The activation enthalpies for pseudorotation of the twist form and the phenylene rotation were 16.3 kcal mol −1 and 8.1 kcal mol −1 , respectively.…”

Section: Classes Of Compounds Used For Columnar Liquid Crystalsmentioning

confidence: 99%

Discotic Liquid Crystals: From Tailor‐Made Synthesis to Plastic Electronics

et al. 2007

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Most associate liquid crystals with their everyday use in laptop computers, mobile phones, digital cameras, and other electronic devices. However, in contrast to their rodlike (calamitic) counterparts, first described in 1907 by Vorländer, disklike (discotic, columnar) liquid crystals, which were discovered in 1977 by Chandrasekhar et al., offer further applications as a result of their orientation in the columnar mesophase, making them ideal candidates for molecular wires in various optical and electronic devices such as photocopiers, laser printers, photovoltaic cells, light-emitting diodes, field-effect transistors, and holographic data storage. Beginning with an overview of the various mesophases and characterization methods, this Review will focus on the major classes of columnar mesogens rather than presenting a library of columnar liquid crystals. Emphasis will be given to efficient synthetic procedures, and relevant mesomorphic and physical properties. Finally, some applications and perspectives in materials science and molecular electronics will be discussed.

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“…Compounds 66b and 66c can be six-fold oxidized at a single potential which was attributed to the missing conjugation of the redox-active peripheral units E [225,226]. Indeed the molecular structure of 66b in the single crystal revealed not only the typical dihedral angle of about 66° between peripheral phenyl groups and the central benzene, but also a dihedral angle of 4-31° between ferrocenyl groups and the peripheral benzene units.…”

Section: Star Compounds With a Benzene Corementioning

confidence: 99%

Star-Shaped Conjugated Systems

2010

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The present review deals with the preparation and the properties of star-shaped conjugated compounds. Three, four or six conjugated arms are attached to cross-conjugated cores, which consist of single atoms (B, C+, N), benzene or azine rings or polycyclic ring systems, as for example triphenylene or tristriazolotriazine. Many of these shape-persistent [n]star compounds tend to π-stacking and self-organization, and exhibit interesting properties in materials science: Linear and non-linear optics, electrical conductivity, electroluminescence, formation of liquid crystalline phases, etc.

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Stereodynamics and Characterization of the Hexa(4‐n‐dodecylbiphenylyl)benzene Hexaanion that Includes a Twisted Benzene Core

Cited by 11 publications

References 70 publications

New acenaphthene-1,2-diimine and its reduction to the tetraanion. Molecular structures of 1,2-bis[(trimethylsilyl)imino]acenaphthene and its lithium derivatives

New acenaphthene-1,2-diimine and its reduction to the tetraanion. Molecular structures of 1,2-bis[(trimethylsilyl)imino]acenaphthene and its lithium derivatives

Discotic Liquid Crystals: From Tailor‐Made Synthesis to Plastic Electronics

Star-Shaped Conjugated Systems

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