organic compounds
Crystal structures are reported for three substituted 1H-imidazole-4,5-dicarbonitrile compounds used as catalysts for the coupling reaction of nucleoside methyl phosphonamidites, namely 2-(3′,5′-dimethylbiphenyl-2-yl)-1H-imidazole-4,5-dicarbonitrile, C19H14N4, (I), 2-(2′,4′,6′-trimethylbiphenyl-2-yl)-1H-imidazole-4,5-dicarbonitrile, C20H16N4, (II), and 2-[8-(3,5-dimethylphenyl)naphthalen-1-yl]-1H-imidazole-4,5-dicarbonitrile, C23H16N4, (III). The asymmetric unit of (I) contains two independent molecules with similar conformations. There is steric repulsion between the imidazole group and the terminal phenyl group in all three compounds, resulting in the nonplanarity of the molecules. The naphthalene group of (III) shows significant deviation from planarity. The C—N bond lengths in the imidazole rings range from 1.325 (2) to 1.377 (2) Å. The molecules are connected into zigzag chains by intermolecular N—HNimidazole [for (I)] or N—H·Ncyano [for (II) and (III)] hydrogen bonds.
organic compounds
The conformations of the anilino(phenyl)methyl groups are similar in four related diethyl [(arylamino)(4-ethynylphenyl)methyl]phosphonates. In each compound, the P—C bond has an approximate staggered conformation, with the aniline and ethynylphenyl groups in gauche positions with respect to the P=O double bond, and the two six-membered rings are almost perpendicular.