FIG. 1.

(Top) Crystal structure of benzophenone. The crystal has space group symmetry P2₁2₁2₁ with four molecules per unit cell. Molecules 1–4 are of the same unit cell represented by the rectangular parallelepiped. Molecules 2–4 are 180° rotated about the crystallographic a, b, and c axes, respectively, with respect to molecule 1. (Bottom) Molecular structures of benzophenone (left) and diphenylnitroxide (right) with oxygen atoms in red, nitrogen in blue, and carbon atoms in black. The figure was rendered in VESTA software.⁴⁴