Isomeric nitrophthalimides: sheets built from N-H center dot center dot center dot O and C-H center dot center dot center dot O hydrogen bonds

Molecules of 3- nitrophthalimide, C8H4N2O4, are linked into sheets by a combination of one N - H ... O hydrogen bond [ H ... O = 1.99 Angstrom, N ... O = 2.8043 ( 14) Angstrom and N - H ... O = 176degrees ] and two independent C - H ... O hydrogen bonds [ H ... O = 2.36 and 2.56 Angstrom, C ... O = 3.1639 ( 16) and 3.4386 ( 16) Angstrom, and C - H ... O = 142 and 153degrees], and these sheets are linked into pairs by a single pi - pi stacking interaction. Molecules of isomeric 4- nitrophthalimide are linked into sheets by a combination of one three- centre N - H ... ( O) (2) hydrogen bond [ H ... O = 2.14 and 2.55 Angstrom, N ... O = 2.974 ( 3) and 3.231 ( 3) Angstrom, N - H ... O = 151 and 131degrees, and O ... H ... O = 76degrees] and two independent two- centre C - H ... O hydrogen bonds [ H ... O = 2.38 and 2.54 Angstrom, C ... O = 3.257 ( 4) and 3.452 ( 4) Angstrom, and C - H ... O = 156 and 168degrees].