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Issue 18, 1999
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Orientational isomerism in bridging 2-pyridyl complexes: orthometallation of (S )-nicotine and (R)-1-(4-pyridyl)ethanol in triosmium clusters

Abstract

Diastereomeric orthometallated products, formed by treating [Os3(CO)10(MeCN)2] with (S )-nicotine or (R )-1-(4-pyridyl)ethanol, have been partially separated by TLC but completely so by HPLC. The two diastereomers of [Os3(µ-H){µ-(R )-NC5H3CH(OH)Me-4}(CO)10] 1 and 2 and four isomers of [Os3(µ-H){µ-(S )-NC5H3C4H7NMe}(CO)10], 3 to 6, two diastereomers each for the products of metallation at the 2 and 6 positions respectively, have been separated and characterized by circular dichroism (CD) spectra to obtain their relative configurations. The CD spectra in the 230–500 nm wavelength range are totally characteristic of the configuration of the Os3CN group at atoms. A crystal structure determination for isomer 2 has allowed absolute configurations of all isomers to be established. There is little enantioselection in the orthometallation process and no detectable interconversion of isomers. The compound [Os3(µ-H)2{µ-(S )-NC5H3C4H7NMe}2(CO)8] was also obtained as a complex isomeric mixture which was not separated.

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Supplementary files


Article type: Paper
DOI: 10.1039/A902061F
J. Chem. Soc., Dalton Trans., 1999, 3289-3294

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    Orientational isomerism in bridging 2-pyridyl complexes: orthometallation of (S )-nicotine and (R)-1-(4-pyridyl)ethanol in triosmium clusters

    A. J. Deeming, M. J. Stchedroff, C. Whittaker, A. J. Arce, Y. De Sanctis and J. W. Steed, J. Chem. Soc., Dalton Trans., 1999, 3289
    DOI: 10.1039/A902061F

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