Syntheses and structures of complexes of .alpha.,.beta.-unsaturated carbonyl compounds and the chiral rhenium fragment [(.eta.5-C5H5)Re(NO)(PPh3)]+: divergent kinetic and thermodynamic O:C/C:C and O:C/C.tplbond.C binding selectivities Academic Article uri icon

abstract

  • Reactions of the substitution-labile dichloromethane complex [(η5-C5H5)Re(NO)(PPh3)-(ClCH2C1)]+BF4- with α, β-unsaturated aldehydes and ketones are described. Acrolein gives a π OC complex, which cleanly isomerizes in the solid state (100 °C) to a π CC complex. Crotonaldehyde gives both π and σ OC complexes (52:48, CH2Cl2, room temperature), which convert at 80 °C to a π CC complex. Methyl vinyl ketone gives a σ OC complex, which is characterized by NMR at −25 °C. At room temperature, a π CC complex forms. Other acyclic vinyl ketones behave similarly. Cyclopentenone and cyclohexenone give σ OC complexes that only partially isomerize to π CC complexes at 60–90 °C. The acetylenic ketone 4-phenyl-3-butyn-2-one gives a σ OC complex at −25 °C. At room temperature, a π CC complex forms. The crystal structure of a π CC complex of trans-4-hexen-3-one is determined. The NMR, configurational, and conformational properties of the preceding complexes, all of which can exist in several isomeric forms, are analyzed in detail. These data show that, with respect to the rhenium fragment [(η5-C5H5)Re(NO)(PPh3)]+, the OC groups of α, β-unsaturated aldehydes and ketones are the kinetically preferred binding sites, but the CC or CC groups are generally the thermodynamically preferred binding sites. © 1993, American Chemical Society. All rights reserved.

author list (cited authors)

  • Wang, Y., Agbossou, F., Dalton, D. M., Liu, Y., Arif, A. M., & Gladysz, J. A.

citation count

  • 22

publication date

  • July 1993