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1996 (2)
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1Author    Hans Bock, Klaus Ziemer, Christian Näther, Holger Schödel, Markus Kleine, Mark SievertRequires cookie*
 Title    Donator/Akzeptor-Komplexe von Alkyl-und Aminobenzolen, Anthracen oder Pyren mit l,3,5-Cyan-/Nitro-benzolen: Kristallisation, Strukturen und Elektronenspektren Interactions in Crystals, 89 [ 1 -3] Donor/Acceptor Complexes of Alkyl and Aminobenzenes, Anthracene or Pyrene and 1,3,5-Cyano/nitro-benzenes: Crystallisation, Structures and Electronic Spectra  
 Abstract    The following mixed-stack donor/acceptor complexes {D • • • A}00 have been cry­ stallized and their structures determined: {hexam ethylbenzene--3,5-dicyano-l-nitroben­ zene hexamethylbenzene---3,5-dinitro-l-cyanobenzene}^, {pyrene- • -3,5-dinitro-l-cyano-ben zen e}^ , {anthracene---(3,5-dinitro-l-cyanobenzene)2}oo, {N,N-dimethylanilin---3,5-di-nitro-l-cyanobenzene}^ and { l^-phenylenediam ine-'-S^-dinitro-l-cyanobenzene}^. Their lattice packing consists of parallel layers, which contain either donors and acceptors as for hexamethylbenzene and pyrene or composite ones as in the 1:2 complex of anthracene with each one of the acceptors above and below its peripheral rings. The isostructural hexamethyl­ benzene complexes exhibit almost identical packing coefficients as well as a hexagonal coplanar arrangement of the C6(CH 3)6 donors. Weak intermolecular van der Waals interactions are also observed between antiparallel cyano substituents. The interplanar n distances range between 334 and 353 pm, /. e. around 340 pm of two van der Waals n radii. In none of the complexes, however, significant structural changes in either the donor or the acceptor components due to the complex formation are observed. In both the crystals as well as in solution, the donor/acceptor complexes exhibit colours between yellow and red; their long-wavelength charge transfer ab­ sorption maxima, therefore, correspond to a lowering in excitation energy of only up to 1 eV relative to that of the components. The different charge transfer in the ground and the CT excited states is also discussed referring to other data such as vertical first ionization energies or interplanar distances {D---A}, as well as to results from semiempirical calculations based on the crystal structure data determined and including approximate configuration interaction. Wechselwirkungen in Kristallen, 89 [1 -3] A u sgan gsp u n k te 
  Reference    Z. Naturforsch. 51b, 1538—1554 (1996); eingegangen am 27. Dezember 1995 
  Published    1996 
  Keywords    Donor/Acceptor-Complexes, Single Crystal Structures, UV/VIS Spectra 
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 TEI-XML for    default:Reihe_B/51/ZNB-1996-51b-1538.pdf 
 Identifier    ZNB-1996-51b-1538 
 Volume    51 
2Author    H. Bocka, T. H. Auck3, C. N. Äthera, Z. HavlasbRequires cookie*
 Title    Wechselwirkungen in Kristallen, 35 [ 1, 2]  
 Abstract    Einkristallzüchtung von Na0 ^C(NO2)3 [***] aus Etherlösungen zu einem polymeren Band [(Na" 9 C (N 0 2)3) D io x a n ^ und einem Lösungsmittel-getrennten Ionenpaar [(Na0 /18-Krone-6)(THF)2]0 [(Na0 /18-K rone-6)(O N O -C e (NO 2)2)2]e Interactions in Crystals, 35 [1, 2] Single Crystal Growths of Na0 e C (N O 2)3 [***] from Ether Solutions to a Polymer Band [(Na0 e C (N O2)3)Dioxane]TO and to a Solvent-Separated Ion Pair [(Na0 /18-Crown-6)(THF)2]0 [(Na0 /18-C row n-6)(O N O -C e (N O 2)2)2]e The sodium salt of the most simple polynitro-substituted hydrocarbon anion, Na0 e C (N O 2)3, (for a hazard warning cf. [***]) crystallizes from ether solutions without and with addition of 18-crown-6 either in a polymer band, [(Na®0 C (N O 2)3)dioxane]oo, or as a solvent-separated ion pair, [(Na®/18-crown-6)(THF2]0 [(Na®/18-crown-6)(O2N -C e (N O 2)2)2]e . The Na® cations are each 8-fold coordinated in hexagonal bipyramidal arrangement. According to extensive quantum-chemical calculations based on the structure coordinates, the formation of these novel salts can be traced back to the charge distribution in the anions e C (N 0 2)3, which due to negatively charged oxygen centers are favorable complex ligands. The structure determining effects of solvation are discussed. 
  Reference    Z. Naturforsch. 49b, 1012—1020 (1994); eingegangen am 31. Januar 1994 
  Published    1994 
  Keywords    Trinitromethanide Salts, Single Crystal Structure, M N DO Calculations, Solvation Effects 
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 TEI-XML for    default:Reihe_B/49/ZNB-1994-49b-1012.pdf 
 Identifier    ZNB-1994-49b-1012 
 Volume    49 
3Author    Hans Bocka, Sabine Nicka, ChristianN. Äthera, JanW. Bats3, Professor Franz-GustavRequires cookie*
 Title    Strukturen ladungsgestörter Moleküle, 47 [1 , 2 ] Dinatrium-und Dikalium-Nitranilate: Die Cyanin-Verzerrung der Kohlenstoff-Sechsringe Structures of Charge-Perturbed Molecules 47 [1,2] Disodium and Dipotassium Nitranilates: The Cyanine Distortion of the Six-Membered Carbon Ring  
 Abstract    Crystals of lemon yellow dipotassium nitranilate and of yellow disodium nitranilate di­ hydrate have been grown and their structures determined at 290 and 200 K. The six-member-ed, 0 2N-disubstituted rings show a pronounced cyanine distortion with all four CO bonds identical and the two (0 C C (N 0 2) C 0) e chains connected by single CC bonds of each 156 pm length. In the anhydrous K® salt, the ring is planar, but in the Na® hydrate salt it exhibits a twist conformation. Quantum chemical calculations allow to reproduce the structure in every detail, demonstrate strong charge alternation along the cyanine chains with considerable delocalization into the 0 2N acceptor substituents, and suggest that the rather long connecting CC bonds contain positively charged carbon centers on both ends. In addition, metal ion coordination effects as well as the rather high pKa value of nitranilic acid are rationalized. 
  Reference    Z. Naturforsch. 49b, 1021—1030 (1994); eingegangen am 17. März 1994 
  Published    1994 
  Keywords    Cyanine Distortion of C6-Rings, Single Crystal Structures, Semiempirical Calculations 
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 TEI-XML for    default:Reihe_B/49/ZNB-1994-49b-1021.pdf 
 Identifier    ZNB-1994-49b-1021 
 Volume    49 
4Author    Hans Bock, Sabine Nick, Christian Näther, Wolfgang BenschRequires cookie*
 Title    Wechselwirkungen in Kristallen, 63 [1, 2]  
 Abstract    Kristallisation und Strukturbestimmung von 1,2-Dimesitoylbenzol und von Bis(hydrogen-l,2-dimesitoylbenzol)-dinatrium-bis(ethylendiamin) Interactions in Crystals, 63 [1, 2] Crystallization and Structure Determ ination of 1,2-Dimesitoylbenzene and of Bis(hydrogen-l,2-dimesitoylbenzene)-disodium-bis(ethylendiamine) 
  Reference    Z. Naturforsch. 50b, 605 (1995); eingegangen am 18. August 1994 
  Published    1995 
  Keywords    1, 2-Dimesitoylbenzene, Radical A nion Sodium Salt, Single Crystal Structures, M N D O Calculations 
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 TEI-XML for    default:Reihe_B/50/ZNB-1995-50b-0605.pdf 
 Identifier    ZNB-1995-50b-0605 
 Volume    50 
5Author    H. Bock, C. Arad, C. Näther, I. G. Öbel, A. John, R. BaurRequires cookie*
 Title    Elektronentransfer und Kontaktionen-Bildung, 45 [1, 2] Strukturänderungen bei der Einelektronen-Reduktion von Tetraphenyl- butatrien zum Radikalanion und bei der Zweifach-Deprotonierung von Tetraphenyl-butin-2 zum Tetraphenylbutatrien-Dianion Electron Transfer and Contact Ion Pair Form ation, 45 [1 ,2 ] Structural Changes on Single Electron R eduction of Tetraphenylbutatriene to its Radical A nion and on Twofold D eprotonation of Tetraphenylbutyne-2 to the Tetraphenylbutatriene D ianion  
 Abstract    Tetraphenylbutatriene is reduced under aprotic conditions to its ESR/ENDOR-spectro-scopically characterized radical anion and to its dianion, with both electron transfers quasi-reversible according to cyclovoltammetric measurements. The alkali cation salts, the red con­ tact ion pair [(H ^C ^C j K N a^H iC O C H iC H iO C H ^d and the dark violet contact ion triple [(H3C6)4C4" ' KLi^H ^CO CH iCIU O CH O ?^ can be prepared by single electron reduction at a sodium metal mirror or by twofold de-protonation of l,l,4,4-tetraphenylbutyne-2 using lithium-/;-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< — >Ce -C = C -C < within the cumulene chain is discussed based on MNDO calculations for the structures determined. Ausgangspunkt: Die Strukturen von K um ulenen 
  Reference    Z. Naturforsch. 51b, 1381—1390 (1996); eingegangen am 15. November 1995 
  Published    1996 
  Keywords    Tetraphenylbutatriene Radical Anion and Dianion Salts, Cyclovoltammetry, ESR/ENDOR Spectra, Single Crystal Structures 
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 TEI-XML for    default:Reihe_B/51/ZNB-1996-51b-1381.pdf 
 Identifier    ZNB-1996-51b-1381 
 Volume    51 
6Author    H. Bocka, J. M. Eureta, J. W. Bats3, Z. HavlasbRequires cookie*
 Title    Strukturen sterisch überfüllter Moleküle, 39 [1,2] Einkristall-und Gasphasen-Strukturen von l,4-Bis(trimethylsiloxy)benzol Structures of Sterically Overcrowded Molecules 39 [1,2] Single Crystal and Gas Phase Structures o f l,4-Bis(trimethylsiloxy)benzene  
 Abstract    l,4-Bis(trim ethylsiloxy)benzene has been crystallized both by vacuum sublimation and from «-heptane solution, which each yielded colourless plates with identical monoclinic unit cell dim ensions (P 2 Jn, Z = 4). The conform ation o f C[ symmetry shows the two (H 3C)3SiO-substituents to be conrotationally twisted around the 0 -(C 6H4) -0 axis by dihedral angles o f ± 60°. According to the photoelectron spectroscopic ionisation pattern and its K oopm ans' as­ signment, IEV" = -e f MI, by AM 1 eigenvalues, the gas phase structure should also be o f C, symmetry. The results o f geometry-optimized M N D O , A M I or P M 3 calculations for the monosubstituted derivative H 5C6-O S i(C H 3)3 are compared with respect to the quality o f their fit to the measured data. Ausgangspunkt: Molekülkonformationen sterisch überfüllter 1,4-Benzol-Derivate 
  Reference    Z. Naturforsch. 49b, 288—2 (1994); eingegangen am 1. Oktober 1993 
  Published    1994 
  Keywords    Sterically Overcrowded Organosilicon M olecules, Single Crystal Structure, Photoelectron Spectroscopy, Quantum Chemical Calculations 
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 TEI-XML for    default:Reihe_B/49/ZNB-1994-49b-0288.pdf 
 Identifier    ZNB-1994-49b-0288 
 Volume    49