Structure and Bonding in Hexa-tert-butyl-hexa-peri-hexabenzocoronene Sandwich Complexes of Ruthenium

2018 ◽  
Vol 71 (4) ◽  
pp. 222
Author(s):  
Matthias Lein
Keyword(s):  
Electronic Interaction ◽  
Polyaromatic Hydrocarbon ◽  
Electronic Effects ◽  
Aromatic System ◽  
Tert Butyl ◽  
Coordination Sites ◽  
Site Selectivity ◽  
Sterically Demanding ◽  
Close Proximity ◽  
Steric Influence

We evaluate the balance of steric and electronic effects in the site selectivity of the binding of [Rh(Me5Cp)]+ ([RhCp·]+) to the three possible coordination sites of the polyaromatic hydrocarbon (PAH) hexa-tert-butyl-hexa-peri-hexabenzocoronene (HBBC). We find that despite the close proximity of sterically demanding tert-butyl groups to the methyl groups of the Cp* ligand, the extent of steric repulsion is minor compared to electronic interaction from bond formation and that the site selectivity is best explained in terms of the electronics of the (poly) aromatic system. This is in contrast to previous investigations on similar systems with a COD ligand where steric influence has been shown to dominate selectivity.

Influence des groupes tert-butyle, triméthylsilyle et triméthylgermyle sur la stéréochimie de réactions d'addition en série cyclohexénique. I. Synthèse des alcènes et hydroboration

1974 ◽  
Vol 52 (24) ◽  
pp. 4133-4138 ◽  
Author(s):  
Christian Freppel ◽  
Marc-André Poirier ◽  
Jean-Claude Richer ◽  
Yvette Maroni ◽  
Georges Manuel
Keyword(s):  
The Other ◽  
Electronic Effects ◽  
Tert Butyl ◽  
The One ◽  
Steric Influence

Syntheses of 1-tert-butyl-(1a), 1-trimethylsilyl-(1b) and 1-trimethylgermanyl-4,4-dimethylcyclohexene (1c) are described as are those of 6-tert-butyl- (2a), 6-trimethylsilyl- (2b) and 6-trimethylgermanyl-3,3-dimethylcyclohexene (2c). The stereochemistry of the hydroboration of these alkenes is examined. The stereochemistry is governed, on the one hand, by the steric influence of the various substituents and on the other by the steric and electronic effects of the trimethylsilyl and trimethylgermanyl groups. [Journal translation]

N-Fluoro-(3,5-di-tert-butyl-4-methoxy)benzenesulfonimide (NFBSI): A sterically demanding electrophilic fluorinating reagent for enantioselective fluorination

2011 ◽  
Vol 132 (3) ◽  
pp. 222-225 ◽  
Author(s):  
Hiroyuki Yasui ◽  
Takeshi Yamamoto ◽  
Takehisa Ishimaru ◽  
Takeo Fukuzumi ◽  
Etsuko Tokunaga ◽  
...  
Keyword(s):  
Tert Butyl ◽  
Sterically Demanding

Medium-sized cyclophanes, part 59:1 Nitration of [3.3]- and [3.3.3]metacyclophanes — Through-space electronic interactions between two or three benzene rings

2002 ◽  
Vol 80 (2) ◽  
pp. 207-215 ◽  
Author(s):  
Takehiko Yamato ◽  
Koji Tsuchihashi ◽  
Noriko Nakamura ◽  
Mai Hirahara ◽  
Hirohisa Tsuzuki
Keyword(s):  
Acetic Anhydride ◽  
Electronic Interaction ◽  
Reaction Conditions ◽  
Tert Butyl ◽  
Mixed Acid ◽  
Butyl Group ◽  
Tert Butyl Group ◽  
Starting Compound ◽  
Nitration Product ◽  
Fuming Nitric Acid

The two tert-butyl groups of anti-6,15-di-tert-butyl-9,18-dimethoxy[3.3]metacyclophane (anti-4) are both ipso-nitrated even under mild reaction conditions such as copper(II) nitrate in an acetic anhydride solution because of the decreased deactivation of the second aromatic ring by the introduced nitro group. On the other hand, anti-5,13-di-tert-butyl-8,16-dimethoxy[2.2]metacyclophane (anti-1) undergoes replacement of only one tert-butyl group under the same reaction conditions. The higher yields of the twofold ipso-nitration product anti-7 were obtained in nitration of anti-4 with fuming nitric acid or mixed acid (HNO3–H2SO4). Thus, the number of ipso-nitrations at the tert-butyl groups of anti-4 was strongly affected by the reactivity of the nitration reagent. Nitration of the corresponding syn-conformer syn-4 with copper(II) nitrate in an acetic anhydride solution, however, led only to the recovery of the starting compound. The presently developed procedure was further applied to the direct removal of the tert-butyl group by electrophilic substitution of the larger-sized ring macrocyclic metacyclophanes, cone- and partial-cone-tri-tert-butyl[3.3.3]metacyclophanes 11.Key words: [3n]metacyclophanes, conformation, ipso-nitration, through-space electronic interaction, crystal structure.

scholarly journals Disentangling the size-dependent geometric and electronic effects of palladium nanocatalysts beyond selectivity

2019 ◽  
Vol 5 (1) ◽  
pp. eaat6413 ◽  
Author(s):  
Hengwei Wang ◽  
Xiang-Kui Gu ◽  
Xusheng Zheng ◽  
Haibin Pan ◽  
Junfa Zhu ◽  
...  
Keyword(s):  
Metal Nanoparticles ◽  
Rational Design ◽  
Aerobic Oxidation ◽  
Atomic Layer ◽  
Electronic Effects ◽  
Coordination Sites ◽  
Layer Deposition ◽  
Palladium Nanocatalysts ◽  
The Right ◽  
Site Selective

The prominent size effect of metal nanoparticles shapes decisively nanocatalysis, but entanglement of the corresponding geometric and electronic effects prevents exploiting their distinct functionalities. In this work, we demonstrate that in palladium (Pd)–catalyzed aerobic oxidation of benzyl alcohol, the geometric and electronic effects interplay and compete so intensively that both activity and selectivity showed in volcano trends on the Pd particle size unprecedentedly. By developing a strategy of site-selective blocking via atomic layer deposition along with first principles calculations, we disentangle these two effects and unveil that the geometric effect dominates the right side of the volcano with larger-size Pd particles, whereas the electronic effect directs the left of the volcano with smaller-size Pd particles substantially. Selective blocking of the low-coordination sites prevents formation of the undesired by-product beyond the volcano relationship, achieving a remarkable benzaldehyde selectivity and activity at the same time for 4-nm Pd. Disentangling the geometric and electronic effects of metal nanoparticles opens a new dimension for rational design of catalysts.

2,2′:6′,2′′-Terpyridine substituted in the 4′-position by the solubilizing and sterically demanding tert-butyl group: a surprisingly new ligand

2012 ◽  
Vol 41 (10) ◽  
pp. 2890 ◽  
Author(s):  
Edwin C. Constable ◽  
Nik Hostettler ◽  
Catherine E. Housecroft ◽  
Peter Kopecky ◽  
Markus Neuburger ◽  
...  
Keyword(s):  
Tert Butyl ◽  
Butyl Group ◽  
Tert Butyl Group ◽  
Sterically Demanding ◽  
Group A

scholarly journals Crystal structure of bis(acetonitrile-κN)(4,4′-di-tert-butyl-2,2′-bipyridine-κ2 N,N′)platinum(II) bis(tetrafluoridoborate) packing as head-to-head dimers

2018 ◽  
Vol 74 (5) ◽  
pp. 695-697
Author(s):  
Chris Joseph ◽  
Vladimir N. Nesterov ◽  
Bradley W. Smucker
Keyword(s):  
Crystal Structure ◽  
Building Block ◽  
Π Interactions ◽  
Tert Butyl ◽  
Close Proximity

The crystal structure of a platinum(II) supramolecular building block, [Pt(dbbpy)(NCCH3)2](BF4)2 (dbbpy = 4,4′-di-tert-butyl-2,2′-bipyridine, C18H24N2) is an example of a rare head-to-head dimer, even with the bulky tert-butyl groups of the bipyridine. This packing motif still enables significant π–π interactions between two pyridyl groups, and may result from the close proximity of the tetrafluoridoborate ions to the platinum(II) complexes, resulting in intramolecular H...F distances between 2.156 and 2.573 Å.

Synthesis, photophysical characterization and DFT studies on fluorine-free deep-blue emitting Pt(II) complexes

2016 ◽  
Vol 71 (5) ◽  
pp. 463-473
Author(s):  
Jan Sanning ◽  
Linda Stegemann ◽  
Marvin Nyenhuis ◽  
Constantin G. Daniliuc ◽  
Nikos L. Doltsinis ◽  
...  
Keyword(s):  
Picolinic Acid ◽  
Blue Shift ◽  
Ancillary Ligand ◽  
Dft Studies ◽  
High Solubility ◽  
Deep Blue ◽  
Coordination Sites ◽  
Square Planar ◽  
Sterically Demanding ◽  
Blue Phosphorescent

AbstractHerein we show that cyclometalated, square planar Pt(II) complexes can be tuned to achieve deep-blue phosphorescent emitters. For this purpose, the introduction of an electron-donating moiety on two different bidentate NˆN and NˆO fluorine-free luminophores, namely 2-(1H-tetrazol-5-yl)pyridine and picolinic acid, was carried out. The remaining two coordination sites of the Pt(II) metal center were filled by a sterically demanding cyclometallating unit, namely a tertiary phosphite CˆP ligand. This ancillary ligand avoids aggregation and provides high solubility in organic solvents. Based on this approach, we were able to blue-shift the emission of the complexes down to 411 nm, and to achieve a maximal photoluminescence quantum yield of 56% in the solid state.

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