A boron-centered radical: a potassium-crown ether stabilized boryl radical anion

2016 ◽  
Vol 52 (86) ◽  
pp. 12714-12716 ◽  
Author(s):  
Ningning Yuan ◽  
Wenqing Wang ◽  
Ziye Wu ◽  
Sheng Chen ◽  
Gengwen Tan ◽  
...  
Keyword(s):  
Free Radical ◽  
Crown Ether ◽  
Radical Anion ◽  
Intermediate Stage ◽  
Ion Pair ◽  
Radical Anions ◽  
Contact Ion Pair

A boron radical contact ion-pair has been isolated, an intermediate stage between free radical anions and neutral radicals of boron.

Elektronentransfer und Kontaktionen-Bildung, 42 [1,2] Cyclovoltammetrische und ESR / ENDOR-Untersuchungen der Einelektronen-Reduktion von Diphenochinonen / Electron Transfer and Contact Ion Pair Formation, 42 [1,2] Cyclovoltammetric and ESR / ENDOR Investigations of the One-Electron Reduction of Diphenoquinones

1995 ◽  
Vol 50 (11) ◽  
pp. 1699-1716
Author(s):  
Andreas John ◽  
Hans Bock
Keyword(s):  
Radical Anion ◽  
Ion Pairs ◽  
Ion Pair ◽  
Pair Formation ◽  
Coupling Constants ◽  
Semiquinone Radical ◽  
Additional Information ◽  
Ion Pair Formation ◽  
Contact Ion Pair ◽  
The Difference

Semiquinone radical anions are prototype compounds for contact ion pair formation with metal counter cations. In order to investigate the still open question whether bulky alkyl groups can sterically interfere, diphenoquinone derivatives O=C(RC=CH)2C=C(HC=CR)2C=O with R = C(CH3)3, CH(CH3)2 and CH3 have been selected and the following ESR/ENDOR results are obtained for the alkaline metal cations: The tetrakis(tert-butyl)-substituted radical anion only adds Li⊕ and Na⊕, while K⊕ forms no ion pair. The 3,3ʹ,5,5ʹ-tetra(isopropyl)diphenoquinone radical anion is accessible to all cations Me⊕, although Rb⊕ and Cs⊕ seem to be present solvent-separated in solution. The tetramethyl-substituted radical anion unfortunately polymerizes rapidly. Additional information concerns the ESR/ENDOR proof for ion triple radical cation formation [Li⊕ M•⊖Li⊕]•⊕, or the difference in the coupling constants upon Me⊕ docking at one δ⊖O=C group, suggesting that about 87% of the spin density is located in the cation-free molecular half of the diphenoquinone radical anion. Based on the wealth of ESR/ENDOR information, crystallization of the contact ion pairs and their structural characterization should be attempted.

scholarly journals Elektronentransfer und Kontaktionen-Bildung, 45 [1, 2] Strukturänderungen bei der Einelektronen-Reduktion von Tetraphenylbutatrien zum Radikalanion und bei der Zweifach-Deprotonierung von Tetraphenyl-butin-2 zum Tetraphenylbutatrien-Dianion / Electron Transfer and Contact Ion Pair Formation, 45 [1,2] Structural Changes on Single Electron Reduction of Tetraphenylbutatriene to its Radical Anion and on Twofold Deprotonation of Tetraphenylbutyne-2 to the Tetraphenylbutatriene Dianion

1996 ◽  
Vol 51 (10) ◽  
pp. 1381-1390 ◽  
Author(s):  
H. Bock ◽  
C. Arad ◽  
C. Näther ◽  
I. Göbel ◽  
A. John ◽  
...  
Keyword(s):  
Radical Anion ◽  
Structural Changes ◽  
Ion Pair ◽  
Single Electron ◽  
Single Crystal Structures ◽  
Contact Ion Pair ◽  
Dark Violet ◽  
Electron Reduction ◽  
Triple H ◽  
Electron Transfers

Tetraphenylbutatriene is reduced under aprotic conditions to its ESR/ENDOR-spectroscopically characterized radical anion and to its dianion, with both electron transfers quasireversible according to cyclovoltammetric measurements. The alkali cation salts, the red contact ion pair [(H5C6)4C4·⊖][Na⊕ (H3COCH2CH2OCH3)3] and the dark violet contact ion triple [(H5C6)4C4⊖⊖][Li⊕(H3COCH2CH2OCH3)3]2 can be prepared by single electron reduction at a sodium metal mirror or by twofold de-protonation of 1,1,4,4-tetraphenylbutyne-2 using lithium-n-butyl. Their single crystal structures as well as that of the parent acetylene have been determined at low temperatures. The essential structural changes observed are the twisting of both molecular halves (H5C6)2CC relative to each other with increasing negative charge. The simultaneously resulting bond alternancy >C = C = C = C< → >C⊖ - C ≡ C⊖ - C < within the cumulene chain is discussed based on MNDO calculations for the structures determined.

One-dimensional single-helix coordination polymer self-assembled by a crown-ether appended-N-heteroacene radical anion

2019 ◽  
Vol 48 (35) ◽  
pp. 13125-13129 ◽  
Author(s):  
Kyosuke Isoda ◽  
Hinako Takahashi ◽  
Yuichiro Mutoh ◽  
Norihisa Hoshino ◽  
Tomoyuki Akutagawa
Keyword(s):  
Coordination Polymer ◽  
Crown Ether ◽  
Coordination Polymers ◽  
Radical Anion ◽  
Radical Anions ◽  
One Dimensional ◽  
Self Assembled ◽  
Single Helix

Radical anions based on crown-ether appended N-heteroacene with Na+ self-assemble one-dimensional helical coordination polymers.

Computational study of SN 2 reactions promoted by crown ether: Contact ion pair versus solvent-separated ion pair mechanism

2017 ◽  
Vol 118 (11) ◽  
pp. e25547 ◽  
Author(s):  
Sung-Sik Lee ◽  
Vinod H. Jadhav ◽  
Ji-Young Kim ◽  
Su-Jin Kim ◽  
Dong Wook Kim ◽  
...  
Keyword(s):  
Crown Ether ◽  
Computational Study ◽  
Ion Pair ◽  
Contact Ion Pair

Stability of radical anions derived from substituted 5-nitrofurans investigated by ESR spectroscopy

1985 ◽  
Vol 50 (7) ◽  
pp. 1594-1601 ◽  
Author(s):  
Jiří Klíma ◽  
Larisa Baumane ◽  
Janis Stradinš ◽  
Jiří Volke ◽  
Romualds Gavars
Keyword(s):  
Radical Anion ◽  
High Stability ◽  
Esr Spectroscopy ◽  
Reaction Path ◽  
Order Reaction ◽  
Second Order ◽  
Radical Anions ◽  
Second Order Reaction ◽  
Unpaired Electron Density ◽  
The Stability

It has been found that the decay in dimethylformamide and dimethylformamide-water mixtures of radical anions in five of the investigated 5-nitrofurans is governed by a second-order reaction. Only the decay of the radical anion generated from 5-nitro-2-furfural III may be described by an equation including parallel first- and second-order reactions; this behaviour is evidently caused by the relatively high stability of the corresponding dianion, this being an intermediate in the reaction path. The presence of a larger conjugated system in the substituent in position 2 results in a decrease of the unpaired electron density in the nitro group and, consequently, an increase in the stability of the corresponding radical anions.

Steady-State Spectroscopy to Single Out the Contact Ion Pair in Excited-State Proton Transfer

2021 ◽  
Vol 12 (6) ◽  
pp. 1683-1689
Author(s):  
Alexander Grandjean ◽  
J. Luis Pérez Lustres ◽  
Stephan Muth ◽  
Daniel Maus ◽  
Gregor Jung
Keyword(s):  
Excited State ◽  
Steady State ◽  
Proton Transfer ◽  
Ion Pair ◽  
Contact Ion Pair ◽  
Excited State Proton Transfer
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