CRYSTAL-STRUCTURES AND HYDROGEN-BONDING IN ONE-DIMENSIONAL CHAINS OF 4,5-DICYANOIMIDAZOLE AND 4,5-DICHLOROIMIDAZOLE

The crystal structure of 4,5-dicyanoimidazole ((CN)(2)Imd) was determi ned by an X-ray diffraction at room temperature; monoclinic, P2(1)/a, a=7.259(2), b=7.529(1), c=10.0972(9) Angstrom, beta=102.74(1)degrees, V=538.2(2) Angstrom(3), Z=4, R=0.043, and R(w)=0.066 for 1090 observed reflections. Crystal structure of 4,5-dichloroimidazole (Cl(2)Imd) wa s redetermined; tetragonal, P4(1)2(1)2, a=6.843(4), c=24.236(7) Angstr om, V=1134(1) Angstrom(3), Z=8, R=0.043, and R(w)=0.058 for 427 observ ed reflections. Molecules in Cl(2)Imd and in (CN)(2)Imd are linked by intermolecular N-H ... N hydrogen bonds to form one-dimensional chains . The hydrogen bonds in Cl(2)Imd are formed between the ring nitrogen atoms, while those in (CN)(2)Imd are between the ring and the cyano ni trogens. The hydrogen bond distance (3.051(2) Angstrom) of N ... N in (CN)(2)Imd is long, compared with that (2.800(6) Angstrom) in Cl(2)Imd . The weak hydrogen bond in (CN)(2)Imd was also indicated by IR and N- 15 CP/MASNMR spectra.