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'Coupling Sign Determination' in keywords
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1998 (1)
1994 (1)
1Author    Z. NaturforschRequires cookie*
 Abstract    C om plexes of the types R3 P b -F e (C O)2Cp [R = Me (la), Et (lb), 'Pr (lc), 'Bu (Id)]. R2 Pb[Fe(CO)2 Cp] 2 [R = Me (2a), Et (2b)], 'Pr2 (B r)P b -F e(C O)2Cp (3c) and [R2 PbFe(CO) 4 ] 2 [R = Me (4a), Et (4b), 'Pr (4c)], as well as the spiro-complexes Pb[Fe(C O)4 PbR2 ] 2 [R = Me (5a), Et (5b), 'Pr (5c)] and Pb[Fe(CO) 4 ] 4 (6) were studied by multinuclear magnetic reso­ 
  Reference    Z. Naturforsch. 49b, 1781—1788 (1994); received July 28 1994 
  Published    1994 
  Keywords    Carbonyliron-Lead Complexes, NM R Spectra, Coupling Sign Determination, X-Ray 
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 TEI-XML for    default:Reihe_B/49/ZNB-1994-49b-1781.pdf 
 Identifier    ZNB-1994-49b-1781 
 Volume    49 
2Author    Bernd Wrackmeyer3, Jürgen Weidinger3, Heinrich Nöthb, Wolfgang Storchb, Thomas Seifertb, Martina VosteenbRequires cookie*
 Title    Determination of Coupling Signs 17 (119Sn, 15N ) and 2/ ( 119Sn, 117Sn) in Trimethylstannylamines  
 Abstract    The l5N-labelled trimethylstannylamines 1 -3 [(M e3Sn)3N, (M e3Sn)2NPh, (M e3Sn)2N-BCgHi4 (BCgHi4 = 9-borabicyclo[3.3.0]nonyn and the non-labelled 4, Me3 Sn-N(BC8Hi4)2 , were prepared and studied by 1H, 1 C, l5N and l9Sn NMR. The l5N ultrahigh resolution NMR spectra of 1 revealed otherwise unobserved parameters such as 2/ (15N ,S n ,'C) and the isotope induced chemical shift 2 zAl2/l3C (l5N). ll9Sn NM R spectra of 1, recorded under similar con­ ditions, also show new parameters such as V (' |ySn,N,Sn,l3C) which are not resolved in the non-labelled derivative. By using various types o f two-dimensional heteronuclear shift corre­ lations, absolute coupling signs o f l7 (l l9 Sn,15N) (all < 0) in 1 -3 were determined. By the same techniques it proved possible to confirm the negative sign o f :7(Sn,Sn) (-195.4 Hz) in 1. In contrast, the coupling constants 27(Sn,Sn) for 2 (+71.7) and 3 (+62.0) possess a positive sign. This sign inversion, observed here for the first time for apparently similar compounds, demonstrates the enormous influence o f substituents on the nature o f the lone pair o f electrons at the nitrogen atom. It also shows that these experiments for sign determinations o f coupling constants are necessary in order to interpret these data correctly. 
  Reference    Z. Naturforsch. 53b, 1494—1500 (1998); received July 30 1998 
  Published    1998 
  Keywords    Tin, Amines, NM R Data, Ultrahigh Resolution, Coupling Sign Determination 
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 TEI-XML for    default:Reihe_B/53/ZNB-1998-53b-1494.pdf 
 Identifier    ZNB-1998-53b-1494 
 Volume    53