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1995 (2)
1Author    Bernd Wrackmeyer, Udo Dörfler, Wolfgang Milius, Max HerberholdRequires cookie*
 Title    Triferrocenylborane -Molecular Structure in Solution and in the Solid State  
 Abstract    According to a single crystal X-ray structure determination all three ferrocenyl substituents of triferrocenylborane (1) adopt the same orientation with respect to the BC3-plane [P 2 Jc\ monoclinic; Z = 4; a = 1353.5(3), b = 1695.6(3), c = 1056.4(2) pm, ß = 109.27(3)°]. The simu­ lated X-ray powder pattern of the single crystal is identical with the powder diagram o f a macroscopic sample, indicating the presence of a single diastereomer (l a) in the solid state. How ever, at low temperature (< -9 5 °C) in solution, the 13C NM R spectra suggest the pres­ ence of the second diastereomer (lb) in which one ferrocenyl group is oriented opposite to the other two with respect to the central BC3-plane. 
  Reference    Z. Naturforsch. 50b, 201—2 (1995); received July 25 1994 
  Published    1995 
  Keywords    Triferrocenylborane, 13C NMR Spectra, Dynamic Processes, X-Ray 
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 TEI-XML for    default:Reihe_B/50/ZNB-1995-50b-0201.pdf 
 Identifier    ZNB-1995-50b-0201 
 Volume    50 
2Author    C. P., R. S. Tu D, Wolfgang Baumann, Yuri Oprunenko, Harald GüntherRequires cookie*
 Title     
 Abstract    y n a m ic B e h a v io u r o f T e tra m e th y le th y le n e D ia m in e (T M E D A) L ig a n d s in S o lid O r g a n o lith iu m C o m p o u n d s : A V a r ia b le T e m p e r a tu r e 13C a n d 15N Dedicated to Professor Dr. W . Müller-Warmuth on the occasion of his 65th birthday The dynamic behaviour of tetramethylethylene diamine (TMEDA) ligands in three organometallic complexes, dimeric phenyllithium, [Li(tmeda)/*-Ph]2 (1), lithium cyclopentadienide, [Li(tmeda)]C5H5 (2), and dilithium naphthalendiide, trans-[Li(tmeda)]2C10H8 (3), has been studied by CP/MAS 13C and 15N as well as 7Li MAS NMR spectroscopy of powdered samples. Two dynamic processes with free activation enthalpies of 40 and 68 kJ mol-1, respectively, were detected for 1. The first one can be assigned to ring inversion of the five-membered Li-TMEDA rings, while the second is caused by a complete rotation of the TMEDA ligands or a ring inversion of the central four-membered C-Li-C-Li metallacycle. Fast rotation of the ligands on the NMR time scale was found for 2, while 3 shows 180° ring flips of the Li-TMEDA groups, which are characterized by an energy barrier AG" (317) of 64 kJ mol-1. 
  Reference    Z. Naturforsch. 50a, 429—438 (1995); received November 8 1994 
  Published    1995 
  Keywords    CP/MAS NMR, 13C-NMR, 15N-NMR, 7Li NMR, dynamic processes, organometallics 
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 TEI-XML for    default:Reihe_A/50/ZNA-1995-50a-0429.pdf 
 Identifier    ZNA-1995-50a-0429 
 Volume    50