Go toArchive
Browse byFacets
Bookbag ( 0 )
'Stereoisomers' in keywords
Results  10 Items
Sorted by   
Publication Year
1994 (2)
1992 (1)
1991 (2)
1987 (1)
1982 (1)
1981 (1)
1980 (2)
1Author    Reinhard Benn, Werner RiemerRequires cookie*
 Title    Two-Dimensional (2D-J) NMR Spectroscopy for Analysis of Isomers and Heterocouplings  
 Abstract    The use of two-dimensional NMR spectroscopy (2D-J) for the identification of isomers and heterocouplings is demonstrated. The routine application of this new method to practical NMR problems is discussed. 
  Reference    Z. Naturforsch. 36b, 488—491 (1981); received November 27 1980 
  Published    1981 
  Keywords    2-Dimensional NMR, Stereoisomers, Heterocouplings 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_B/36/ZNB-1981-36b-0488.pdf 
 Identifier    ZNB-1981-36b-0488 
 Volume    36 
2Author    W. Preetz, G. RimkusRequires cookie*
 Title    Darstellung und Schwingungsspektren von Chloro-Bromo-Platinaten(IV) einschließlich der Stereoisomeren Preparation and Vibrational Spectra of Chloro-Bromo-Platinates(IV) Including Stereoisomers  
 Abstract    The mixed chloro-bromo complexes [PtClnBr6-n] 2_ > n = 1-5, are separated by ion exchange chromatography on diethylaminoethylcellulose. The separation of corresponding stereoisomers for n — 2, 3, 4 is not possible. Due to the stronger trans-effect of Br compared with Cl, on treatment of [PtBrß] 2-with Cl -in the presence of Br2 nearly pure cis-isomers, and by reaction of [PtClsBr] 2-and cis-fPtC^Bro] 2-with Br~/Br2 completely pure trans-isomers are formed. The stereoselectivity of the successive ligand exchange reactions is better than in corresponding series of Re, Os and Ir. The highly resolved vibrational spectra allow the distinction of the mixed ligand complexes as well as the estimation of purity of the isomers. All allowed stretching frequencies are observed and assigned according to point groups D4h, C4V, C3V and C2V-Especially in the i>(Pt-Br) region it is possible to distinguish bands arising either from symmetric Br-Pt-Br or asymmetric Cl-Pt-Br axes. The UV/VIS spectra exhibit systematic hypsochromic shifts on the successive exchange of Br-ligands by Cl. A critical discussion of the literature concerning chloro-bromo-platinates-(IV) shows the importance of effective separation processes for the isolation of pure mixed ligand complexes. 
  Reference    Z. Naturforsch. 37b, 579—586 (1982); eingegangen am 21. Dezember 1981 
  Published    1982 
  Keywords    Chloro-Bromo-Platinates(IV), Stereoisomers, ^rans-Effect 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_B/37/ZNB-1982-37b-0579.pdf 
 Identifier    ZNB-1982-37b-0579 
 Volume    37 
3Author    Dierk Martin, Eckhard SchlimmeRequires cookie*
 Title    Preparation of Ureidonucleosides of the Threonine Isomers  
 Abstract    The hypermodified ureidonucleoside N6[((9-ß-D-ribofuranosyl-9H-purine-6-yl)amino)car-bonyl]-L-threonine (5) is a constituent of transfer ribonucleic acid (tR N A) and is secreted as a tR N A catabolite in body fluids such as blood, milk and urine. Compound 5 and the isomeric ureidonucleosides bearing D-threonine (9), L-allo-(7) and D-allo-threonine (11) as side chain moieties were synthesized on a preparative scale. The amido protons of 5 and 9 cause two separate 'H NM R signals whereas 7 and 11 cause multiplets. The ,3C NM R signals of all carbon atoms of the allo-amino acid side chains (7, 11) are shifted downfield of the corre­ sponding signals in compounds 5 and 9. The chemically protected intermediate compound adenosine urethane (3) is potentially of interest in the analysis of amino acids because it may be converted to nucleosides of the ureido type by reaction with amino acids in biological matrices. 
  Reference    Z. Naturforsch. 49c, 834—8 (1994); received April 15 1994 
  Published    1994 
  Keywords    Adenosine, 2-Amino-3-hydroxybutanoic Acid, Stereoisomers, Threonine, Ureidonucleosides 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_C/49/ZNC-1994-49c-0834.pdf 
 Identifier    ZNC-1994-49c-0834 
 Volume    49 
4Author    Hans Jürgen Nestler, Hermann BieringerRequires cookie*
 Title    Synthese und herbizide Wirksamkeit der D-und L-Enantiomeren des 2-[4-(2.4-Dichlorphenoxy)-phenoxy] -propionsäure-methylesters Synthesis and Herbicidal Activity of the D-and L-Methyl 2-[4-(2,4-Dichlorophenoxy)-phenoxy]-propionate Enantiomers  
 Abstract    The D-and L-enantiomers of the wild oat herbicide diclofop-methyl (title compound) were prepared utilizing resolution operations and by synthetic routes with optically active compounds as starting material. The dextro-rotatory product which the D(R)-configuration can be attributed to, was found to be the herbicidally active species. 
  Reference    Z. Naturforsch. 35b, 366—371 (1980); eingegangen am 5. November 1979 
  Published    1980 
  Keywords    Phenoxy-phenoxy-propionic Acid Ester, Diclofop-methyl, Stereoisomers, Grass Herbicide 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_B/35/ZNB-1980-35b-0366.pdf 
 Identifier    ZNB-1980-35b-0366 
 Volume    35 
5Author    Reinhard Benn, Borislay Bogdanović, Peter Göttsch, Klaus SchlichteRequires cookie*
 Title    ?/ 3 -Allyl-hydrogensulfidoiiickel(II)-Korapi exe ?y 3 -Allyl-hydrogensulfidonickel(II) Complexes  
  Reference    Z. Naturforsch. 35b, 200—206 (1980); eingegangen am 10. September 1979 
  Published    1980 
  Keywords    ?7 3 -Allyl-hydrogensulfidonickel(II) Complexes, Stereoisomers, Metal Sulfide Catalysts, NMR Spectra, Deuterium Labeling 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_B/35/ZNB-1980-35b-0200.pdf 
 Identifier    ZNB-1980-35b-0200 
 Volume    35 
6Author    W. Preetz, H.N V AllwördenRequires cookie*
 Title    Darstellung und Schwingungsspektren von Chloro-Bromo-Ruthenaten(IV) einschließlich der Stereoisomeren Preparation and Vibrational Spectra of Chloro-Bromo-Ruthenates(IV) Including Stereoisomers  
 Abstract    The mixed chloro-bromo complexes [RuCl"Br 6 _"] 2_ , n = 1—5, have been separated for the first time by ion exchange chromatography on diethylaminoethylcellulose. Due to the stronger trans-effect of Br compared with Cl, on treatment of [RuBr 6 ] 2 ~ with Cl" in the presence of Br 2 nearly pure ciy//ac-isomers,andbyreactionof [RuCl 6 ] 2 " withBr"/Br 2 nearlypurerran5/mer-isomersforn = 2,3,4 are formed. The vibrational spectra of the mixed ligand complexes are completely assigned according to point groups D 4h , C 4v , C 3v and C 2v , respectively. The bands are observed in the characteristic regions: v(RuCl): 340-270 > v(RuBr): 245-190 > <3(ClRuCl): 170-140 > ö(ClRuBr) > <3(BrRuBr): 125—90 > v L : < 100 cm" 1 . The lower stability of the hexahalogeno complexes of Ru(IV), 4d, compared with the homologous complexes of Os(IV), 5d, is confirmed by a decrease of the force field constants by approximately 15%. 
  Reference    Z. Naturforsch. 42b, 381—386 (1987); eingegangen am 18. Dezember 1986 
  Published    1987 
  Keywords    Chloro-Bromo-Ruthenates(IV), Stereoisomers, r/wis-Effect, IR Spectra, Raman Spectra 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_B/42/ZNB-1987-42b-0381.pdf 
 Identifier    ZNB-1987-42b-0381 
 Volume    42 
7Author    W. Preetz, A. WendtRequires cookie*
 Title    Darstellung, Schwingungsspektren und Normalkoordinatenanalyse der Chloro-Bromo-Technetate(IV), ITcCl^B^.J2-, n = 0 -6  
 Abstract    The mixed chloro-brom o-technetates(IV), [TcCl"Br6_J2_, n = 1 -5 , have been separated for the first time by ion exchange chromatography on diethylaminoethyl-cellulose. Due to the stronger trans-effect o f Br as compared to Cl, the ligand exchange reactions o f [TcBr6]2" with HC1 and o f [TcClJ2-with HBr proceed stereospecifically, to form either cis/fac-or trans/mer-species for n = 2, 3, 4, respectively. To avoid photoisom erization the com pounds have to be handled in the absence o f light. The IR and Raman spectra o f the ten chloro-bromo-techne-tates(IV), including the pure geometrical isomers, have been recorded at low temperature (80 K) and completely assigned to structures o f point groups O h, D 4h, C4v, C3v, and C2v, sup­ ported by normal coordinate analysis based on a general valence force field. Due to the differ­ ent /ra«s-influences C l< Br in asymmetric C l'-T c -B r ' axes, the T c -B r ' bonds are strength­ ened and the T c -C l' bonds are weakened, as indicated by valence force constants, for T c -Br' on average 6% higher and for T c -C l' 10% lower, as compared with the values calculated for symmetric Br—T c— Br and C l-T c —Cl axes, respectively. 
  Reference    Z. Naturforsch. 46b, 1496—1502 (1991); eingegangen am 15. Mai 1991 
  Published    1991 
  Keywords    Chloro-Bromo-Technetates(IV), Stereoisomers, /ra«s-Effect, /ra«5-Influence, Vibrational Spectra 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_B/46/ZNB-1991-46b-1496.pdf 
 Identifier    ZNB-1991-46b-1496 
 Volume    46 
8Author    W. Preetz, A. WendtRequires cookie*
 Title    Darstellung, Schwingungsspektren und Normalkoordinatenanalyse der Chloro-Bromo-Technetate(IV), ITcCl^B^.J2-, n = 0 -6  
 Abstract    The mixed chloro-brom o-technetates(IV), [TcCl"Br6_J2_, n = 1 -5 , have been separated for the first time by ion exchange chromatography on diethylaminoethyl-cellulose. Due to the stronger trans-effect o f Br as compared to Cl, the ligand exchange reactions o f [TcBr6]2" with HC1 and o f [TcClJ2-with HBr proceed stereospecifically, to form either cis/fac-or trans/mer-species for n = 2, 3, 4, respectively. To avoid photoisom erization the com pounds have to be handled in the absence o f light. The IR and Raman spectra o f the ten chloro-bromo-techne-tates(IV), including the pure geometrical isomers, have been recorded at low temperature (80 K) and completely assigned to structures o f point groups O h, D 4h, C4v, C3v, and C2v, sup­ ported by normal coordinate analysis based on a general valence force field. Due to the differ­ ent /ra«s-influences C l< Br in asymmetric C l'-T c -B r ' axes, the T c -B r ' bonds are strength­ ened and the T c -C l' bonds are weakened, as indicated by valence force constants, for T c -Br' on average 6% higher and for T c -C l' 10% lower, as compared with the values calculated for symmetric Br—T c— Br and C l-T c —Cl axes, respectively. 
  Reference    Z. Naturforsch. 46b, 14961—1502 (1991); eingegangen am 15. Mai 1991 
  Published    1991 
  Keywords    Chloro-Bromo-Technetates(IV), Stereoisomers, /ra«s-Effect, /ra«5-Influence, Vibrational Spectra 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_B/46/ZNB-1991-46b-1496_A1b.pdf 
 Identifier    ZNB-1991-46b-1496_A1b 
 Volume    46 
9Author    W. Preetz, M. M. AntheyRequires cookie*
 Title    Schwingungsspektren und Normalkoordinatenanalyse der Bromo-Iodo  
 Abstract    Osmate(IV), [O sB r ^ J 2-, n = 0 -6 V ibrational S pectra and N o rm al C oordinate A nalysis o f B rom o-Iodo-O sm ates(IV), [OsBr"I6_"]2-, n = 0 -6 The IR and Raman spectra o f the ten brom o-iodo-osm ates(IV) [OsBr"I6_n]2-, n = 0 -6 , in­ cluding the geometrical isomers for n = 2, 3, 4, have been recorded at low temperature. The vibrational spectra are completely assigned according to point groups Oh, D 4h, C4v, C3v, and C2v, as supported by normal coordinate analyses based on a general valence force field. D ue to the different mzns-influences B r < I in asymmetric axes B r '-O s -I ', the O s -I ' bonds are strengthened and the O s-B r' bonds are weakened, as indicated by valence force constants, for O s -I ' on average 4% higher and for O s-B r' 4% lower, as compared with the values calculat­ ed for symmetric I -O s -I and B r -O s —Br axes, respectively. 
  Reference    Z. Naturforsch. 47b, 1667—1672 (1992); eingegangen am 10. August 1992 
  Published    1992 
  Keywords    Brom o-Iodo-Osm ates(IV), Stereoisomers, mms-Influence, Vibrational Spectra, Norm al Coordinate Analysis 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_B/47/ZNB-1992-47b-1667.pdf 
 Identifier    ZNB-1992-47b-1667 
 Volume    47 
10Author    Bromo, P. Prillwitz, W. PreetzRequires cookie*
 Title    Darstellung, Schwingungsspektren und Normalkoordinatenanalyse der  
 Abstract    The IR and Raman spectra of the ten brom o-iodo-rhenates(IV) [ReBr"I6_"]2 -, n = 0 -6 , including the geometrical isomers for n -2,3,4, have been recorded at 80 K. The vibrational spectra are com pletely assigned according to point groups O h, D 4h, C4v, C3v, and C2v, as supported by normal coordinate analyses based on a general valence force field. Due to the different mms-influences Br < I in asymmetric axes B r '-R e -I ', the R e -I ' bonds are strengthened and the R e -B r ' bonds are weakened, as indicated by valence force constants, for R e -I ' on average 8,5% higher and for O s -B r ' 8,3% lower, as compared with the values calculated for symmetric I -R e -I and B r -R e -B r axes, respectively 
  Reference    Z. Naturforsch. 49b, 753—7 (1994); eingegangen am 7. März 1994 
  Published    1994 
  Keywords    -Iodo-Rhenate(IV), [ReBr, !^, ]2-, n = 0 -6 Brom o-Iodo-Rhenates(IV ), Stereoisomers, rra/is-Influence, Vibrational Spectra, Normal Coordinate Analysis 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_B/49/ZNB-1994-49b-0753.pdf 
 Identifier    ZNB-1994-49b-0753 
 Volume    49