| | 6 | Author
| Wolfgang Kaim | Requires cookie* | | | Title
| Zur Reaktion aromatischer Phosphanderivate mit Elektronen, III [1, 2] Phosphan-Borane, -Alane und -Gallane On the Reaction of Aromatic Phosphane Derivatives with Electrons, III [1, 2] Phosphane-Boranes, -Alanes, and -Gallanes  | | | | Abstract
| The 1:2 molecular complexes formed from l,4-phenylenebis(dimethylphosphane) and boranes, trialkyl-aluminum and -gallium have been reduced by potassium in THF in the presence of a K + -complexing crown ether. The bis(borane) complex anion radicals proved to be quite persistent, whereas corresponding aluminum radical complexes could only be observed below 240 K. The bis(trimethylgallium) complex gave gallium metal on reduction with potassium. An ESR spectro-scopic comparison with the anion radicals of the free ligand, of corresponding chalcogenides, imines and phosphonium salts demonstrates negligible effects of P-complexation on the JI spin distribution but high sensitivity of the 31 P coupling constant towards coordination of electrophiles at the basic P(III) centers. | | | |
Reference
| (Z. Naturforsch. 40b, 61—66 [1985]; eingegangen am 1. Oktober 1984) | | | |
Published
| 1985 | | | |
Keywords
| Molecular Complexes, Reduction, Anion Radicals, ESR Spectra | | | |
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| default:Reihe_B/40/ZNB-1985-40b-0061.pdf | | | | Identifier
| ZNB-1985-40b-0061 | | | | Volume
| 40 | |
| 9 | Author
| Conny Vogler, Wolfgang Kaim, H.-D Hausen | Requires cookie* | | | Title
| Zweikernige Bisphosphankupfer(I)-Komplexe mit dem 2,2 -Bipyrimidin-Brückenliganden: Strukturelle Analogie zu "Blauen" Kupferzentren und Reduktion zu paramagnetischen Spezies Dinuclear Bis(phosphane)copper(I) Complexes with 2,2'-Bipyrimidine as Bridging Ligand: Structural Analogy to " Blue" Copper Centers and Reduction to Paramagnetic Species | | | | Abstract
| Dinuclear complexes [(PR3)2C u(//:/74-bpym)Cu(PR3)2](BF4)2 with the bis-chelating bridging ligand 2,2'-bipyrimidine (bpym) and various m onodentate and bidentate phosphanes were synthesized via a four com ponent "self assembly" reaction. The reversible electrochemical reduction to m onocationic radical complexes was studied by cyclic voltammetry and electron spin resonance (ESR). Highly resolved ESR spectra revealed the presence o f the bpym anion radical ligand via resolved hyperfine coupling with 'H, 14N , 31P, 63Cu and 65Cu nuclei. The variation o f phosphane ligands was accompanied by significant changes o f electrochemical potentials which were rationalized considering electronic and structural effects. The configura tional flexibility o f Cu(I) in this environment is evident from the X-ray crystal structure ana lysis o f [(PPh3)2C u(//:^4-bpym)Cu(PPh3)2](BF4)2 H2O C H 3OH for which the coordination at the metal can be described as 3 + 1 (N N'P + P'), qualitatively similar to the (NN'S + S') arrange ment around the type 1 Cu centers o f "blue" copper proteins. Intramolecular cooperative n donor/;: acceptor/^ donor "Sandwich" interactions provide parts o f the driving force for this highly distorted coordination geometry which illustrates the proclivity o f Cu(I) towards such an "entatic state" arrangement. | | | |
Reference
| Z. Naturforsch. 48b, 1470—1480 (1993); eingegangen am 5. Mai 1993 | | | |
Published
| 1993 | | | |
Keywords
| Copper Complexes, Structure, Electrochemistry, ESR Spectra, Phosphane Ligands | | | |
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| default:Reihe_B/48/ZNB-1993-48b-1470.pdf | | | | Identifier
| ZNB-1993-48b-1470 | | | | Volume
| 48 | |
| 10 | Author
| S. V. Volkov, V. A. Bandur, N. I. Buryak | Requires cookie* | | | Title
| The Structure and Catalytic Properties of Coordination Polyhedra of 3d-Metals in Metaphosphate Melts | | | | Abstract
| By EAS and ESR spectroscopy, oxygenated complexes of d-metals have been established in high-temperature melts N a P 0 3-C r 20 3-0 2 and N a P 0 3-C 0 0 -0 2 and others of the type M (P 0 3)J(.0 2, where M is Cr, Co, V, and their structure has been established. The ' "O/'^O exchange reaction in the N a P 0 3-V 20 5-0 2 melt has been studied by mass spectrometry both in the presence of the oxidized substrate and in its absence. A general approach has been proposed explaining the interaction between polyphosphate complexes of 3d-metal ions and molecular oxygen and the oxidation ability of the oxygenated complexes in terms of the MO theory. It has been established three types of interaction between 3d-metal ions and molecular oxygen: donor, acceptor and donor-acceptor ones. Oxygenated complexes of the ions of the midle of the 3d-elem ent series (d4-d 7) were found to possess the revealed "par tial" oxidation ability towards alkanes. | | | |
Reference
| Z. Naturforsch. 49b, 1539—1543 (1994); received March 10 1994 | | | |
Published
| 1994 | | | |
Keywords
| EAS Spectra, ESR Spectra, M etaphosphate Melts | | | |
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| default:Reihe_B/49/ZNB-1994-49b-1539.pdf | | | | Identifier
| ZNB-1994-49b-1539 | | | | Volume
| 49 | |
| 12 | Author
| Mit Alkylderivaten Von Bor, GalliumUnd Aluminium, Indium, Wolfgang Kaim | Requires cookie* | | | Title
| Koordinationsverbindungen des reduzierten Pyrazins | | | | Abstract
| The alkyls MR3 (M = B, AI, Ga, In) react with pyrazine (Pz) and sodium in THF to yield persistent radical complexes Pz(MR2)2 ,+ MR4~ (1). Use of TIR3 leads to rapid deposi-tion of thallium metal. The formation of these ionic complexes 1 is the result of MR3 dissociation into +MR2 and -MR4 ions. All radicals have been identified and characterized by ESR; the data reveal the influence of N3B back bonding in the boron derivative. | | | |
Reference
| Z. Naturforsch. 36b, 677—682 (1981); eingegangen am 6. März 1981 | | | |
Published
| 1981 | | | |
Keywords
| Pyrazine, Alkali Metal Reduction, Group III Alkyls, Radical Complexes, ESR Spectra | | | |
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| default:Reihe_B/36/ZNB-1981-36b-0677.pdf | | | | Identifier
| ZNB-1981-36b-0677 | | | | Volume
| 36 | |
| 13 | Author
| Wolfgang Kaim | Requires cookie* | | | Title
| Koordinationschemie reduzierter N-Heterozyklen. Komplexe des Pyrazin-Radikalanions mit Phenylmetallkationen +MPh von Beryllium, Magnesium und Zink Coordination Chemistry of Reduced N-Heterocycles. Complexes of Pyrazine Anion Radical with Phenyl Metal Cations + MPh of Beryllium, Magnesium and Zinc | | | | Abstract
| The diphenyls MPh2 (M = Be, Mg, Zn, Cd, Hg) have been reacted with pyrazine (Pz) in tetrahydrofuran. Only the magnesium derivative undergoes electron transfer to yield the 1:1 radical complex [Pz(MgPh)] -. However, in the presence of sodium or potassium persistent 1:2 complexes [Pz(MPh)2]t are formed with M = Be, Mg, Zn. Use of the higher homologues CdPh2 and HgPh2 leads to reduction to the metals. The 1:2 complexes have been characterized by ESR spectroscopy; metal coupling constants of 9 Be, 25 Mg and 67 Zn could be determined in natural isotopic abundance. | | | |
Reference
| Z. Naturforsch. 36b, 1110—1116 (1981); eingegangen am 4. Mai 1981 | | | |
Published
| 1981 | | | |
Keywords
| Pyrazine, Electron Transfer, Group II Aryls, Radical Complexes, ESR Spectra | | | |
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| default:Reihe_B/36/ZNB-1981-36b-1110.pdf | | | | Identifier
| ZNB-1981-36b-1110 | | | | Volume
| 36 | |
| 16 | Author
| H. Ans Bocka, W. Olfgang Kaima, Mitsuo Kira3, LouisR. Eneb, H. Einz-G, V. Ünther, Ieheb | Requires cookie* | | | Title
| Radikalionen, 61 [ 1 , 2 ] Dialkylamino-substituierte Acetylene und Allene: Ionisation, Oxidation und AlCI3-katalysierte Wasserstoffübertragung Radical Ions, 61 [1, 2] D ialkylam ino-substituted Acetylenes and Allenes: Ionisation, O xidation and AlCl3-Catalyzed Hydrogen Transfer | | | | Abstract
| The photoelectron (P E) spectra of bis(dialkylam ino) acetylenes R 2N — C = C —N R 2 and o f tet-rakis(dialkylam ino) allenes (R 2N)2C = C = C (N R 2)i with R = C H 3, C2H 5 exhibit characteristic ionization patterns which are assigned to re radical cation states of the two m olecular halves twisted against each other. The low first ionization potentials betw een 7.0 eV and 7.7 eV stim u lated attempts to oxidize using A1C13 in H 2CC12 or D 2CC12. The hyperfine structured E SR spectra observed can be unequivocally assigned to the ethylene radical cations R 2N — HC = CH — N R 2 © which are formed from the obviously non-persistent species R2N —C ^ C — N R 2 ® via a hydrogen transfer. During the oxidation o f the dialkylam ino-substituted allenes no paramagnetic interm edi ates could be d etected , presumably due to a rapid dimerisation o f the allene radical cation (R 2N)2C = C = C (N R 2)2'®. | | | |
Reference
| Z. Naturforsch. 39b, 763—770 (1984); eingegangen am 28. N ovem ber 1983 | | | |
Published
| 1984 | | | |
Keywords
| D ialkylam ino Substituted n Systems Radical Cations, ESR Spectra, PE Spectra | | | |
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| default:Reihe_B/39/ZNB-1984-39b-0763.pdf | | | | Identifier
| ZNB-1984-39b-0763 | | | | Volume
| 39 | |
| 17 | Author
| E. N. Esr, HartmutB. Stegmann, Klaus Stolze, Klaus Scheffler | Requires cookie* | | | Title
| ESR-und ENDOR-Untersuchungen der Autoxidationsprodukte des Adrenalons und analoger Verbindungen Investigations of the A utoxidation Products of Adrenalone and Related Compounds | | | | Abstract
| The signs of the proton coupling constants of adrenalone sem iquinone and related compounds were determ ined by E N D O R and T R IP L E resonance studies, thereby verifying the increment system described in our previous paper [2], Com parison of the spin-distribution of several substi tuted acylcatechols showed the conform ational influence on the coupling constants due to mesomeric interaction of the carbonyl group with the arom atic 7r-system. A drenalone and other N -m onosubstituted catecholam ines showed rather stable secondary radi cals after the decay of the prim ary sem iquinone radical. They were identified as substituted dihydropyrazinium cation radicals after selective deuteration and comparison of their ESR-, EN D O R -and TRIPLE -resonance spectra with those of the non-deuterated species. They are formed by cyclic condensation of two molecules with subsequent oxidation. E in fü h ru n g | | | |
Reference
| Z. Naturforsch. 41b, 776 (1986); eingegangen am 24. Januar 1986 | | | |
Published
| 1986 | | | |
Keywords
| A drenalone, Semiquinones, ESR Spectra, E N D O R Spectra | | | |
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| default:Reihe_B/41/ZNB-1986-41b-0776.pdf | | | | Identifier
| ZNB-1986-41b-0776 | | | | Volume
| 41 | |
| 18 | Author
| Sylvia Ernst, Volker Kasack, Christian Bessenbacher, Wolfgang Kaim | Requires cookie* | | | Title
| Ein-und zweikernige Bis(2,2'-bipyridyI)ruthenium-Komplexe mit N,0-Mode!liganden für Dehydrogenase-Cofaktoren Mono-and Binuclear Bis(2,2'-bipyridine)ruthenium Complexes with N,0-Ligands Modelling Dehydrogenase Cofactors | | | | Abstract
| Coordination of substitutionally inert [Ru(bpy) 2 ] 2+ fragments (bpy: 2,2'-bipyridine) to the a-iminoketone chelate ligands pyrazine-2-dimethylcarboxamide (4) and 4,7-phenanthroline-5,6-dione (5) yields the complexes [(N,0-4)Ru(bpy) 2 ] 2 ®, [(0,0'-5 e)Ru(bpy) 2 ]® and {(N,0; N',0'-5)[Ru(bpy) 2 ] 2 } 4 ® which exhibit a rich electrochemistry. The distinctly different electronic structures of the complexes are evident from the ESR behaviour of paramagnetic intermediates: N.O-coordinated complexes have the unpaired electron residing in the ligand n system upon reduction, albeit with g<2 for the complex of 4 but with g>2 for the binuclear complex of 5. The paramagnetic 0,0'-coordinated mononuclear complex with 5 has its redox potentials shifted positively relative to that of the binuclear system. These results are particularly noteworthy because 4 and 5 can be regarded as model compounds for the flavin and methoxatin dehydrogenase cofactors. | | | |
Reference
| Z. Naturforsch. 42b, 425—430 (1987); eingegangen am 6. August 1986 | | | |
Published
| 1987 | | | |
Keywords
| Dehydrogenase Cofactors, Ruthenium Complexes, Oxidation States, ESR Spectra, a-Iminoketones | | | |
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| default:Reihe_B/42/ZNB-1987-42b-0425.pdf | | | | Identifier
| ZNB-1987-42b-0425 | | | | Volume
| 42 | |
| 19 | Author
| Yuzo Nishida, Naoko Oshino, Tadashi Tokii | Requires cookie* | | | Title
| Crystal Structure and Magnetic Property of the Binuclear Manganese(III) Complex with /u-Acetate and Di-ji-Alkoxo Bridges | | | | Abstract
| Binuclear manganese(III) complex, [Mn : L(u-OCH 3)0<-CH 3 COO)(OHCH : ,)]ClO 4 was pre-pared and characterized in terms of crystal structure determination, magnetic measurement, and ESR spectroscopy, where H 3 L represents the Schiff base derived from salicylaldehvde and 1,5-diamino-3-pentanol. | | | |
Reference
| Z. Naturforsch. 43b, 472—474 (1988); received November 9/December 17 1987 | | | |
Published
| 1988 | | | |
Keywords
| Binuclear Manganese(III) Complex, Crystal Structure, ESR Spectra, Magnetic Property | | | |
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| default:Reihe_B/43/ZNB-1988-43b-0472.pdf | | | | Identifier
| ZNB-1988-43b-0472 | | | | Volume
| 43 | |
| 20 | Author
| Conny Vogler, Wolfgang Kaim | Requires cookie* | | | Title
| Einkernige Bis(triphenylphospin)kupfer(I)-Komplexe der Bidiazine M ononuclear Bis(triphenylphosphine)copper(I) Complexes of the Bidiazines | | | | Abstract
| The cationic d 10 metal complexes [(bdz)Cu(PPh3).J+ o f the n accepting bidiazine (bdz) che late ligands 3,3'-bipyridazine, 2,2'-bipyrazine, 2,2'-and 4,4'-bipyrimidine were synthesized and compared with the analogous com plex o f 2,2'-bipyridine. The long wavelength metal-to-ligand charge transfer (M LCT) absorption maxima and the reduction potentials indicate relatively little 7i* orbital stabilization by +Cu(PPh3)2. The particular d orbital splitting in a tetrahedral ligand field results in an additional contribution from J , to the energy difference between the first and second MLCT band. Only the most easily reduced com plexes o f 4,4'-bipyrimidine and 2,2'-bipyrazine yield neutral radical complexes ("Cu(0)") which were characterized by ESR spectroscopy. | | | |
Reference
| Z. Naturforsch. 47b, 1057—1062 (1992); eingegangen am 11. März 1992 | | | |
Published
| 1992 | | | |
Keywords
| Copper Complexes, Heterocyclic Ligands, Electrochemistry, Absorption Spectroscopy, ESR Spectra | | | |
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| default:Reihe_B/47/ZNB-1992-47b-1057.pdf | | | | Identifier
| ZNB-1992-47b-1057 | | | | Volume
| 47 | |
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