Quinones as Electron Acceptors. X-Ray Structures, Spectral (EPR, UV−vis) Characteristics and Electron-Transfer Reactivities of Their Reduced Anion Radicals as Separated vs Contact Ion Pairs

2006 ◽  
Vol 128 (51) ◽  
pp. 16708-16719 ◽  
Author(s):  
Jian-Ming Lü ◽  
Sergiy V. Rosokha ◽  
Ivan S. Neretin ◽  
Jay K. Kochi
Keyword(s):  
Electron Transfer ◽  
Ion Pairs ◽  
Electron Acceptors ◽  
X Ray ◽  
Contact Ion Pairs ◽  
Anion Radicals

Elektronentransfer und Ionenpaare, 15 [ 1– 3] Radikalanion und Radikal-Kontakt-Ionenpaare von Dimesityl-tetraketon / Electron Transfer and Ion Pairing, 15 [1-3] Radical Anion and Radical Ion Pairs of Dimesityl Tetraketone

1990 ◽  
Vol 45 (8) ◽  
pp. 1197-1204 ◽  
Author(s):  
H. Bock ◽  
P. Hänel ◽  
H.-F. Herrmann
Keyword(s):  
Electron Transfer ◽  
Radical Anion ◽  
Ion Pairs ◽  
Ion Pairing ◽  
Single Electron ◽  
Single Electron Transfer ◽  
Temperature Dependent ◽  
Contact Ion Pairs

The radical anion of dimesityltetraketone (ERed, I = -0.40 V) is easily generated in THF by potassium mirror/[2.2.2]-cryptand reduction. Its contact ion pairs with Na⊕, Cs⊕ and Ba⊕⊕ counter cations, prepared in THF solution by single electron transfer from the respective metals, are characterized by their ESR/ENDOR spectra, which exhibit temperature-dependent metal couplings of aNa⊕ = 0.061 mT (190 K), aCs⊕ = 0.021 mT (190 K), and aBa⊕⊕ = 0.145 mT (295 K).

Elektronentransfer und Ionenpaar-Bildung, 7 [1, 2] Kontakt-Ionenpaare Schwefel enthaltender Radikalanionen / Electron Transfer and Ion Pairing, 7 [1, 2] Contact Ion Pairs of Sulfur-Containing Radical Anions

1988 ◽  
Vol 43 (10) ◽  
pp. 1240-1246 ◽  
Author(s):  
Hans Bock ◽  
Peter Hänel ◽  
H.-F Herrmann ◽  
Heindirk torn Dieck
Keyword(s):  
Electron Transfer ◽  
Ion Pairs ◽  
Ion Pairing ◽  
Radical Anions ◽  
Contact Ion Pairs ◽  
Sulfur Containing

The structurally different radical anions M⊖ of peralkylated 1-sila-2,5-diazacyclopentane-3,4-dithione and of tetrakis(isopropylthio)-p-benzoquinone are generated by reduction with potassium/2.2.2-cryptand under aprotic conditions in THF solution. On addition of Li⊕B(C6H5)4⊖, both form hitherto elusive sulfur-containing contact ion pairs, which are characterized by their ESR/ENDOR spectra.

An X-Ray Diffraction Study on the Structure of Concentrated Aqueous Caesium Iodide and Lithium Iodide Solutions

1987 ◽  
Vol 42 (4) ◽  
pp. 367-376 ◽  
Author(s):  
Yusuke Tamura ◽  
Isao Okada ◽  
Hitoshi Ohtaki ◽  
Toshio Yamaguchi
Keyword(s):  
Ion Pairs ◽  
Distribution Functions ◽  
Radial Distribution Functions ◽  
X Ray Diffraction ◽  
Lithium Iodide ◽  
X Ray ◽  
Iodide Ions ◽  
X Ray Scattering ◽  
Hydration Structure ◽  
Contact Ion Pairs

X-Ray scattering measurements of 2.78 and 5.56 molal aqueous solutions of caesium iodide and 2.78 and 6.05 molal lithium iodide were carried out at 293 and 343 K Differences in the radial distribution functions (DRDFs) have been obtained between the caesium iodide and lithium iodide solutions of similar composition, the latter being taken as a reference for the data analysis of the former. The DRDFs show a peak arising from Cs - I contact-ion-pairs at 390 pm for all the caesium iodide solutions. The hydration structure of the caesium and iodide ions has been revealed. Effects of the concentration and temperature on the formation of ion-pairs and on the hydration structure of the ions are discussed

Crystal Structure of 3Ni(N03)2.16C6 H5NH2

1990 ◽  
Vol 45 (9-10) ◽  
pp. 1185-1189
Author(s):  
Michael Mahr ◽  
Inge Pabst ◽  
Konrad G. Weil
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Ion Pairs ◽  
X Ray Diffraction ◽  
Nickel Ion ◽  
Ionic Solutions ◽  
Triclinic Space Group ◽  
X Ray ◽  
Lattice Constants ◽  
Contact Ion Pairs

Abstract The Compound 3Ni(NO3)2 -16C6H5NH2 was obtained by crystallization from solutions of Ni(NO3)2 • 6C6H5NH2 -2H2O in aniline. Its crystal structure was determined by single crystal X-ray diffraction. The crystals are triclinic, space group P1 with lattice constants a = 985.2 pm, ft = 1004.5 pm and c = 2514.3 pm, a = 96.34°, ß = 92.63° and y = 89.82°. The structure shows units of four aniline molecules and two slightly distorted nitrate ions in the coordination sphere of each nickel ion. These units are similar to contact ion pairs in concentrated ionic solutions.

Elektronentransfer und Ionenpaar-Bildung, 18 [1 -3] / Electron Transfer and Ion Pairing, 18 [ 1 - 3]

1991 ◽  
Vol 46 (3) ◽  
pp. 326-338 ◽  
Author(s):  
H. Bock ◽  
P. Dickmann ◽  
H.-F. Herrmann
Keyword(s):  
Electron Transfer ◽  
Metal Cation ◽  
Reduction Potential ◽  
Ion Pairs ◽  
Radical Cations ◽  
Membered Ring ◽  
Cation Complexation ◽  
Metal Cation Complexation ◽  
Contact Ion Pairs ◽  
Triple Ion

The redox behaviour of aza-substituted naphtho- and anthraquinones, which offer O=C–C=N– chelate tongs for an advantageous five-membered ring metal cation complexation, is investigated by a combination of cyclovoltammetric and ESR/ENDOR spectroscopic measurements. The formation of paramagnetic contact ion pairs like [(quinoline-5,8-semiquinone)·⊖Me⨁]·, with Me⨁ = Li⨁, Na⨁, Tl⨁, or of triple ion radical cations like [(1,4-diazo-9,10-anthrasemiquinone)eMe⨁]·⨁, with Me⨁ = Li⨁, Na⨁ is corroborated both by shifts of the second reduction potential of up to 0,67 V for e.g. quinoline 5,8-quinone upon addition of Li⨁[B(C6H5)4]⊖ to its DMF solution and by the observation of ESR/ENDOR metal couplings.

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