Crystal and molecular structures of butan-2-one p-nitrophenylhydrazone (1), propanal 2,4-dinitrophenylhydrazone (2), dimethyl 2-oxo-propanedioate phenylhydrazone (3), and dimethyl 2-oxopropanedioate 2,4-dinitrophenylhydrazone (4): hydrogen bonding and bond order in phenylhydrazones

Abstract

Crystals of the title compound (1), C10H13N3O2, are monoclinic, a= 4.119(11), b= 18.992(12), c= 13.992(10)Å, β= 96.0(1)°, space group P21/c, Z= 4. Compound (2), C9H10N4O4, is monoclinic a= 5.333(7), b= 11.488(8), c= 17.713(10)Å, β= 95.0(1)°, space group P21/c, Z= 4. Compound (3), C11H12N2O4, is monoclinic, a= 21.331(14), b= 4.153(10), c= 13.640(12)Å, β= 102.8(1)°, space group P21/a, Z= 4. Compound (4), C11H10N4O8, is monoclinic, a= 11.198(8), b= 14.779(9), c= 8.443(7)Å, β= 92.4(1)°, space group P21/a, Z= 4. All four structures were solved by the statistical method using the SHEL-X-76 system of programs, and refined using full matrix least squares. The numbers of reflexions used in refinement and the final R values are (1) 330, 0.103; (2) 611, 0.059; (3) 863, 0.061; and (4) 1 274, 0.070, respectively. In all cases the (NO2)–Ar–NH–N C–(C O) fragment is essentially planar. The NO2 HN and C O HN separations suggest that there is substantial intramolecular hydrogen bonding. In addition in compound (2) there is evidence for intermolecular as well as intramolecular NO2 H–N bonding in the crystal. In phenylhydrazones whose structures are known, there is an inverse relationship between Ar–NH and N–N bond lengths, and a direct relationship between Ar–N(H) and N C bond lengths.