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- Title
Meisenheimer complex from picric acid and diisopropylcarbodiimide.
- Authors
Rabih O. Al-Kaysi; David Creed; Edward J. Valente
- 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 28° from the mean formerly aryl ring plane; in (5), nitro groups are twisted out of the aryl plane by 1162°. 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.
- Publication
Journal of Chemical Crystallography, 2004, Vol 34, Issue 10, p685
- ISSN
1074-1542
- Publication type
Article