Crystal structure of the solid state photoreactive 2,2′,4,4′,6, 6′-hexaisopropylbenzil

2,2′,4,4′,6,6′-Hexaisopropylbenzil undergoes an intramolecular solid state photochemical cyclization initiated by hydrogen abstraction by a carbonyl oxygen. The crystal structure of the diketone has been determined by X-ray diffraction methods and the molecular geometry was found to possess an inversion centre. There are three hydrogen atoms (and another three are related by the inversion centre) in close contact (2.68, 2.86 and 2.99 Å) with an oxygen atom, which suggests the feasibility of both γ- and δ-hydrogen abstraction. The molecular conformation and geometry at the central diketone moiety are compared with those of other diaryl diketones.