Experimental evidence for the amino-group non-planarity in nitroanilines: neutron diffraction study of 2-methyl-5-nitroaniline at 100 K.
An appreciable degree of pyramidalization of the amine N atom is observed in the title compound. The existence of polar chains, induced by N-H.O synthons, is confirmed. C-H.O interactions, not noted in a previous X-ray study, were found to stabilize further the known head-to-tail assembling of the chains. The structure can be described as non-polar (101) layers, embodying chains interlinked by centrosymmetric dimers, connected by C(aryl)-H.pi interactions. The latter are not present in m-nitroaniline, 2-methyl-4-nitroaniline and other related compounds with chains built from similar N-H.O synthons and assembled head-to-head. This finding implies that an obvious relationship between molecular recognition patterns and crystal structures should not be assumed.
PROFIMO and LANADI, Departamento de Física, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, CC 67 (1900) La Plata, Argentina.
J
Ellena
AE
Goeta
JA
Howard
CC
Wilson
JC
Autino
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Punte