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Journal of Chemical Crystallography

, Volume 34, Issue 10, pp 685–692 | Cite as

Meisenheimer complex from picric acid and diisopropylcarbodiimide

  • Rabih O. Al-Kaysi
  • David Creed
  • Edward J. Valente
Article

Abstract

Reaction of picric acid with diisopropylcarbodiimide produces a pale yellow 1:1 adduct N-(2′,4′,6′-trinitrophenyl)-N,N′-di(isopropyl)urea (5) and a 1:2 adduct fluorescent red zwitterionic Meisenheimer complex (6) as approximately N′,N”,N′”-tri(isopropyl)-4-oxo-6-(isopropyliminio)-2-s-(2H)triazinespiro-1′-2′,4′,6′-trinitro cyclohexadienylide. Crystals of (5) are triclinic, P-1 (#2), with a = 10.444(13) Å, b = 15.47(2) Å, c = 17.74(2) Å, α = 110.43(9)°, β = 99.85(10)°, γ = 92.78(10)°, V = 2629(6) Å3 for Z = 6 (three molecules per asymmetric unit). Crystals of (6) are orthorhombic, Pna21 (#33), with a = 24.12(4), b = 9.011(19) Å, c = 10.87(2) Å, V = 2362(8) Å3 for Z = 4. Nitro groups in the Meisenheimer complex are twisted 2–8° from the mean formerly aryl ring plane; in (5), nitro groups are twisted out of the aryl plane by 11–62°. In the Meisenheimer complex, cationic charge is distributed over an iminium/guanidinium group; anion charge is distributed over the cyclohexadienide ring and attached nitro groups.

Meisenheimer zwitterion picric acid 

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Copyright information

© Springer Science+Business Media, Inc. 2004

Authors and Affiliations

  • Rabih O. Al-Kaysi
    • 1
  • David Creed
    • 1
  • Edward J. Valente
    • 1
  1. 1.Department of Chemistry and BiochemistryThe University of Southern MississippiHattiesburg

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