Crystal and molecular structure of N-phenyl substituted 1,2-, 2,3- and 1,8-naphthalimides

Abstract

The three structures were solved by direct methods and refined by full-matrix least-squares procedure. 2-phenyl-1 H-benz[f]isoindole-1,3(2H)-dione, (compound 1): orthorhombic, space group Pcab, a = 7.618(1) Å, b = 11.717(2) Å, c = 28.540(4) Å, V = 2547.4(7) ų, Z = 8 and d = 1.425 Mg m⁻³, R = 0.038 (R_w = 0.038) for 190 parameters and 820 observations with I > 2.5σ(I). 2-phenyl-1H-benz[e]isoindole-1,3(2 H)-dione (compound 2): orthorhombic, space group Pc2₁ b, a = 6.7042(9) Å, b = 7.4589(9) Å, c = 26.441(7) Å, V = 1322.4(4) ų, Z = 4 and d = 1.373 Mg m⁻³, R = 0.037 (Rw = 0.032) for 190 parameters and 1186 observations with I > 3σ(I). 2-phenyl-1H-benz[de]isoquinoline-1,3(2H)-dione (compound 3): monoclinic, space group C2/c, a = 13.501(3) Å, b = 13.212(4) Å, c = 8.305(2) Å, β = 116.24(2)°, V = 1329(9) ų, Z = 4, and d = 1.366 Mg m⁻³, R = 0.038 (Rw = 0.033) for 71 parameters and 754 observations with I > 3σ(I). The plane of the N-phenyl substituent has an axis which lies in the plane of the naphthalimide part and passes by the carbon atom bound to the nitrogen atom and by the carbon in para position. It makes a dihedral angle with the plane of the naphthalimide moiety of 59.2°, 46.5° and 69.4° for the compounds 1,2 and 3 respectively. This difference in geometry between the three molecules brings new insights into their spectroscopic properties.