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1982 (1)
1975 (1)
1Author    Requires cookie*
 Abstract    nE-Verbindungen (E = P, As) von Elementen der IV. Hauptgruppe (CF3)wE Compounds (E = P, A s) o f Main Group I V Elements S a l m a n A n s a r i und J o s e p h G r o b e Transphosphination reactions of (Me3 M)3 P and Me3 M PH 2 compounds (M = Si, Ge, Sn; Me = CH3) using HE(CF3)2 or H 2 ECF3 (E = P, As) yield derivatives of the types Me3 ME(CF3)2, Me3 ME(H)CF3, and (Me3 M)2 ECF3, respectively. The reactivity of the different systems depends on M (Si < Ge < Sn), E (P < As), and the phosphine [Me3 M PH 2 < (Me3 M)2 PH < (Me3 M)3 P]. Me3 M E(H)CF3 compounds undergo dismutation forming (Me3 M)2 ECF3 and H 2 ECF3. Reactions of the new derivatives with polar com­ pounds (HBr, H 2 E'CF3, Me3 M'Br) result in cleavage of the M -E bond. Decomposition of the CF3 E derivatives occurs by /^-elimination of fluorine yielding Me3 MF besides polymers of unknown structure. 
  Reference    (Z. Naturforsch. 30b, 523—530 [1975]; eingegangen am 25. März/25. April 1975) 
  Published    1975 
  Keywords    Trifluoromethyl Element Compounds, Silylphosphines, Germylphosphines, Stannyl-phosphines, NM R 
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 TEI-XML for    default:Reihe_B/30/ZNB-1975-30b-0523.pdf 
 Identifier    ZNB-1975-30b-0523 
 Volume    30 
2Author    H. Hauer, H.-D Lüdemann, R. JaenickeRequires cookie*
 Title    Free Activation Energies and Activation Volumes for the Amide Rotation in Some Peptides Studied by High Pressure 'H-High Resolution NMR  
 Abstract    From the pressure dependence o f !H high resolution N M R spectra o f two dipeptides (glycylsarcosine and N-acetyl-L-proline-NH-methylamide in the range 0.1 MPa <.p< . 150 MPa the activation volumes A V* for the am ide rotation are derived. This conform ational transition is characterized for glycylsarcosine by A V* = 4 ± 1 cm3 • m ol-1 and for. the proline derivative by AV* = 1 .5 ± 1 cm3 • m ol-1. From the given results the m axim um contribution o f proline cis ^ trans isomerisation to the pressure dependence o f the rate o f reactivation of proteins can be estimated to ~ — 30% per M Pa and proline present. 
  Reference    Z. Naturforsch. 37c, 51—56 (1982); received Septem ber 221981 
  Published    1982 
  Keywords    Activation Volume, High Pressure, NM R, Peptides, Proline-Isom erization 
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 TEI-XML for    default:Reihe_C/37/ZNC-1982-37c-0051.pdf 
 Identifier    ZNC-1982-37c-0051 
 Volume    37