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1Author    J. Heldt, J. R. Heldt, T. Redzimski, H. Diehl, P. SchultzRequires cookie*
 Title    Spectroscopic Studies of Dimethylamino Derivatives of Fluorene  
 Abstract    2-dimethylamino-9-fluorenol and 2-dimethylamino-9(4'dimethylamino)phenyl-9-fiuorenol in polar solvents in the excited state undergo conformation changes in which two fluorescent isomers are created. The isomers (in the local excited (LE) and charge transfer (CT) configuration) pos-sess separate fluorescence bands, one appearing from the S! (LE) state and the second from the intramolecular charge transfer state S, (CT) of the neutral, aromatic molecule. Both bands show a solvatochromic effect. Using the method of the solvent induced Stokes shift of the absorption and fluorescence spectra the permanent dipole moment of the excited state of fluorene and its two derivatives have been determined. The dipole moment of the ground state and the Onsager cavity radius of the studied molecules were calculated with the Auestion Model 1 (AMI) program. 
  Reference    Z. Naturforsch. 55a, 902—908 (2000); received October 31 2000 
  Published    2000 
  Keywords    Isomer, Dual Fluoescence, Solvatochromic Effect, Charge Transfer 
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 TEI-XML for    default:Reihe_A/55/ZNA-2000-55a-0902.pdf 
 Identifier    ZNA-2000-55a-0902 
 Volume    55 
2Author    Joachim Fuchs, Axel Thiele, Rosemarie PalmRequires cookie*
 Title    Strukturen und Schwingungsspektren des Tetramethylammonium -a -dodekawolframatosilikats und des Tetrabutylammonium-/?-dodekawolframatosilikats Structures and Vibrational Spectra of Tetramethylammonium a-Dodecatungstosilicate and Tetrabutylammonium /?-Dodecatungstosilicate  
 Abstract    Dodecatungstosilicates free of crystal water were prepared for the first time by using tetraalkylammonium as cation. The crystal structure of the tetramethylammonium a-dodeeatungstosilicate [N(CH3)4]4SiWi2C>4o (1) and tetrabutylammonium)S-dodecatungs-tosilicate, [N(C4H9)4]4SiWi204o (2) were solved by X-ray diffraction. (1) crystallizes tetragonal in the space group 14 with lattice parameters a = 14.642 A; c= 12.706 A; (2) orthorhombic, space group P2i2x2i with a = 29.277 A, b = 22.181 A and c = 15.381 A. The differences between the two isomeric heteropolyanions are discussed, especially the distances and angles between the tungsten atoms. Comparison of characteristic differences in the vibrational spectra permits the identifica-tion of the isomeric anions. 
  Reference    Z. Naturforsch. 36b, 161—171 (1981); eingegangen am 22. Oktober 1980 
  Published    1981 
  Keywords    Dodecatungstosilicates, Isomers, X-ray, Vibrational Spectra 
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 TEI-XML for    default:Reihe_B/36/ZNB-1981-36b-0161.pdf 
 Identifier    ZNB-1981-36b-0161 
 Volume    36 
3Author    Günter Schmid, Roland BoeseRequires cookie*
 Title    Azaborolinyl Complexes, IX [1] The Crystal and Molecular Structures of Two Isomers of Bis(l-ter£-butyl-2-methyl-??-l,2-azaborolinyl)cobalt  
 Abstract    The crystal and molecular structures of two isomers of bis(l-£er£-butyl-2-methyl-??-l,2-azaborolinyl)cobalt have been determined by single-crystal X-ray diffraction methods. Isomer 1 shows a clockwise, isomer 2 an anti-clockwise conformation of the azaborolinyl rings. In both compounds the azaborolinyl rings have staggered orientations with opposite positions of the tferi-butyl groups. The rings in 1 and 2 are slipped so that the three ring carbon atoms are closer to the cobalt atom than the BN groups. The staggered orientation of the ligands in 2 is probably due to a packing effect, as in similar sandwich complexes the anti-clockwise conformers show eclipsed orientation. 
  Reference    Z. Naturforsch. 38b, 485—492 (1983); eingegangen am 12. November 1982 
  Published    1983 
  Keywords    Azaborolinyl Sandwich Complexes, Cobalt, Isomers, X-Ray 
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 TEI-XML for    default:Reihe_B/38/ZNB-1983-38b-0485.pdf 
 Identifier    ZNB-1983-38b-0485 
 Volume    38 
4Author    Uwe Klingebiel, Norbert Vater, William Clegg, Martin Haase, GeorgeM. SheldrickRequires cookie*
 Title    Synthesis of Silicon-Phosphorus-Rings - Structure of a cis-2,2,4,4-Tetrakis(silylamino)-l,3-diphospha-2,4-disilacyclobutane  
 Abstract    Fluorosilylphosphanes of the type R2SiFPHR' (R = CHMe2, CMe3, NMeSiMe3; R' = H, C6H5; 1-4) are obtained in the reaction of difluorosilanes with lithiated phosphanes in a molar ratio 1:1. Diphosphasilanes (5, 6) and a difluorosilylphosphane (7) are isolated as by-products. 1-4 react with w-QjHgLi to give cyclic silylphosphanes, LiF, and C4H10 (8-11). Dilithiated 5 reacts with F2PN(CMe3)SiMe3 to form of a four-membered SiP3-ring 12. The 31 P NMR spectra of 9 and 11 show signal coalescence for the eis-and tfrans-isomers at room temperature. The crystal structure of the cis-isomer of 11 has been determined. The substituted ring 13 is prepared in the reaction of lithiated 9 and Me2SiF2. 
  Reference    Z. Naturforsch. 38b, 1557—1562 (1983); eingegangen am 6. Juli 1983 
  Published    1983 
  Keywords    Fluorosilylphosphanes, Cyclisation, P-Inversion, Isomers, Crystal Structure 
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 TEI-XML for    default:Reihe_B/38/ZNB-1983-38b-1557.pdf 
 Identifier    ZNB-1983-38b-1557 
 Volume    38 
5Author    JanA K Du Plessis, Hans Rose, RobertA. ShawRequires cookie*
 Abstract    The synthesis of trimethylphosphazenyl -and triphenylphosphazenyl -fluorocy clotri -phosphazatrienes, N3P3F6-n(NPR3)n, by a silylation method using Me3SiNPR3 (R = Me or Ph) is reported. More phosphazenyl groups can be introduced if R = Me than if R = Ph. Isomers have been isolated, as have been mixed phosphazenyl derivatives, N3P3F6 -n-m (NPR3)N(NPR3') m (R = Ph, R' = Me). Substituted fluorophosphazenes, 
  Reference    (Z. Naturforsch. 31b, 997—998 [1976]; received March 4/April 2 1976) 
  Published    1976 
  Keywords    Trimethylphosphazenylfluorocyclotri-phosphazatrienes, Triphenylphosphazenylfluorocyclotri-phosphazatrienes, Isomers, Silylation Method, Steric Effects 
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 TEI-XML for    default:Reihe_B/31/ZNB-1976-31b-0997_n.pdf 
 Identifier    ZNB-1976-31b-0997_n 
 Volume    31 
6Author    Joachim FuchsRequires cookie*
 Title    Kristallstrukturen und Schwingungsspektren zweier  
 Abstract    isomerer Oktadekawolframatodiarsenate, (NH4)6As2W180 62 • #iH20 C rystal S tructures and V ibrational Spectra of Tw o Isom ers of O ctadecatungsto-diarsenate (N H 4)6A s2W 18 0 6 2 • mH20 H o lg er N eu b e rt Six possible structures of A s2W ,80 626~ are discussed, and an exact nom enclature is proposed. The structures of the isomeric title compounds (I and II) were determ ined by X-ray diffraction. I crystallizes in space group P I with lattice param eters a = 12.965(4), b = 14.803(5), c = 18.515(6) Ä; a = 96.280(23)°, ß = 91.420(25)°, y — 115.320(25)°. The anion has the configuration first observed in K6P2W ,80 62-14 H 20 (D awson-structure). II was not known until now. It crystal­ lizes in the trigonal space group R 3 with lattice param eters a — b — 37.857(32). c = 13.108(13) Ä; a — ß = 90°, y = 120°. The structure of this anion differs from the D awson-structure by the 60° rotation of both polar groups of three W 0 6-octahedra (/3-type), followed by the 60° rotation of one of the two new AsWyO,,-units. Both rotations are about the 3-fold axis. The anion is centrosym m etric. Vibrational spectra and preparation of the isomers are described. 
  Reference    Z. Naturforsch. 42b, 951—958 (1987); eingegangen am 4. März/11. Mai 1987 
  Published    1987 
  Keywords    T ungstoarsenates, Isomers, X-Ray, V ibrational Spectra, Preparation 
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 TEI-XML for    default:Reihe_B/42/ZNB-1987-42b-0951.pdf 
 Identifier    ZNB-1987-42b-0951 
 Volume    42