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  • 1
    Electronic Resource
    Electronic Resource
    Diastereoselective Synthesis of Chiral (Triazolinylidene)rhodium Complexes Containing an Axis of Chirality (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 913-919 
    Details
    ISSN: 1434-1948
    Keywords: Chiral carbenes ; Carbene complexes ; Rhodium complexes ; Axial chirality ; Asymmetric hydrosilylation ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Deprotonation of chiral triazolium salts 1 and reaction of the resulting nucleophilic carbenes with [(COD)RhCl]2 or [(NBD)RhCl]2 afforded square-planar complexes 2-6 in yields of 65-95%. The complexes contain an axis of chirality and a diastereomeric excess of up to 97% was achieved. The relative and absolute configurations of these complexes were determined by NMR spectroscopic investigations and X-ray structure analysis. The application of the rhodium(COD) complexes as catalysts in an asymmetric hydrosilylation reaction has been examined, resulting in enantiomeric excesses of up to 44%. Similar results were achieved for aromatic and aliphatic ketones and a nonlinear temperature effect (principle of isoinversion) was observed.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
  • 2
    Electronic Resource
    Electronic Resource
    Diastereoselective Synthesis of the First Enantiomerically Pure (Triazolinylidene)ruthenium(ii) and -rhodium(iii) Chelate Complexes (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 1253-1260 
    Details
    ISSN: 0009-2940
    Keywords: Chiral carbenes ; (Carbene)ruthenium complexes ; (Carbene)rhodium complexes ; Chelate Complexes ; Chirality ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The chloro bridges of the dinuclear complexes [(.65-cymene)-RuCl2]2 and [(.5-C5Me5)RhCl2]2 can be cleaved by reaction wht an N-phenyltriazolium perchlorate (1) and a base, resulting in the formation of (carbene)metal complexes. In this manner, abstraction of one ortho-proton of the phenyl group and elimination of HCl leads to pseudo-tetrahedral ruthenium (2) and rhodium (3) complexes, thereby creating a stereogenic center at the transition metal. By using enantiomerically pure triazolium perchlorates, the diastereoselective synthesis of these complexes with diastereomeric excesses of up to 95% can be achieved, with the possibility of separating the two diastereomers by column chromatography. The relative, and therefore also the absolute configuration of the ruthenium complex (RRu)-2b could be determined by X-ray structure analysis. A stereospecific substitution of chlorine by iodine or acetonitrile to form the diastereomerically pure complexes 4, 5 and 6 (the latter as cationic ruthenium complexes) allows a further variation of the ligands.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971300913
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  • 3
    Electronic Resource
    Electronic Resource
    Synthesis and Stereochemistry of the First Chiral (Imidazolinylidene)- and (Triazolinylidene)palladium(ii) Complexes (1996)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 129 (1996), S. 1483-1488 
    Details
    ISSN: 0009-2940
    Keywords: Chiral carbenes ; (Carbene)palladium complexes ; Axial chirality ; Nomenclature ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction of three equiv. of a chiral imidazolium or triazolium perchlorate with one equiv. of Pd(OAc)2, an excess of NaI and a base leads to the corresponding chiral dicarbenediiodopalladium(II) complexes in chemical yields up to 98% and with the trans isomer as the major product (1, 2). If only one equiv. of the imidazolium or triazolium perchlorate is used, then dinuclear complexes with bridging iodine atoms are formed (3, 4, chemical yield 92 - 94%). The latter can add Lewis basic ligands, e.g. amines, phosphanes or other carbenes, to give mononuclear complexes with one carbene ligand coordinated to the PdI2 fragment (5, 6). Preliminary test experiments with these Pd(II) complexes as catalysts for an enantioselective Heck-type reaction have been carried out.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19961291213
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    Paper (German National Licenses)
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