DIETHYL 2-BENZIMIDAZOL-1-YLSUCCINATE-PICRIC ACID-(1 1) - AN INCLUSIONMOLECULAR-COMPLEX/

The crystal structure of the diethyl 2-benzimidatol-1-ylsuccinate-picr ic acid (1/1) molecular complex has been determined by X-ray diffracti on analysis. Diethyl 2-benzimidazol-1-ylsuccinate molecules form chann els along the a axis, in which the picric acid molecules are located. The benzimidazole moiety and the phenol group are held together by hyd rogen bonding between the hydrogen of the phenol and the N3 atom of be nzimidazole. Additionally, this hydrogen forms an intramolecular hydro gen bond with one O atom of the ortho-nitro group, thus producing a bi furcated hydrogen bond. H-1 NMR spectra in DMSO-d(6) solution and CP/M AS solid C-13 NMR studies of this 2-benzimidazol-1-ylsuccinate-picric acid (1/1) molecular complex, as well as those of dimethyl, diethyl, d i-n-butyl and 1-n-butyl-4-ethyl 2-imidazol-1-ylsuccinates, diethyl 2-p yrazol-1-ylsuccinate, ethyl imidazol-1-ylacetate, ethyl pyrazol-1-ylac etate and ethyl pyrazol-1-ylsuccinate, suggest that the picric acid li nkage depends on the nature of the azole. Actual proton transfer is de duced for the imidazole derivatives, but only weak hydrogen bonding co uld be inferred for pyrazole derivatives.