Collect. Czech. Chem. Commun.
1989, 54, 3245-3252
https://doi.org/10.1135/cccc19893245
Configuration on the C=N double bond of monosubstituted amidines and amidoximes
Bernard Tinanta, Janine Dupont-Fenfaua, Jean-Paul Declercqa, Jaroslav Podlahab and Otto Exnerc
a Laboratoire de chimie physique et de cristallographie, Université Catholique de Louvain, 1348 Louvain la Neuve, Belgium
b Department of Organic Chemistry, Charles University, 128 40 Prague 2, Czechoslovakia
c Institute of Organic Chemistry and Biochemistry, Czechoslovak Academy of Sciences, 166 10 Prague 6, Czechoslovakia
Abstract
Configuration on the C=N double bond of amidines and amidoximes is controlled by steric effects on the second nitrogen atom but there is a difference in the case of N’-monosubstituted derivatives: amidines prefer E configuration (conformation around the C-N bond sp) and amidoximes Z configuration (conformation ap). This was confirmed by the X-ray structures of two analogous model compounds N,N’-dimethyl-4-nitrobenzamidine (monoclinic, P21c, a = 10.855(3), b = 11.043(3), c = 8.593(3) Å, β = 105.69(2)°, V = 991.8(5) Å3, Z = 4, Dx = 1.29 g cm-3, CuKα, λ = 1.5418 Å, μ = 7.91 cm-1, F(000) = 408, T = 291 K, R = 0.065 for 1 265 observed reflections) and N’-methyl-4-nitrobenzamidoxime (monoclinic, P21/a, a = 6.699(2), b = 24.178(9), c = 6.075(2) Å, β = 106.20(3)°, V = 944.9(6) Å3, Z = 4, Dx = 1.37 g cm-3, CuKα, λ = 1.5418 Å, μ =9.22 cm-1, F(000) = 408, T = 291 K, R = 0.079 for 1 278 observed reflections).
