Molecular and Crystal Structure of the α and β Forms of 9,10 -Phenanthrenequinone

Abstract

9,10-Phenanthrenequinone was found to have at least two modifications. One of the forms, (α), belongs to the space group P2/c with α = 16.450(2), b = 7.988(1), c = 7.738(1)Å, β = 103.60(2)°, Z = 4 and has been refined to an R factor of 0.069 on 391 non-zero reflections. Another form (β), belongs to the space group P1 with α = 15.170(2), b = 15.540(1), c = 8.346(1)Å, α = 83.51(1), β = 76.57(1), ø = 31.21(1)°, Z = 4 and has been refined to an R factor of 0.092 on 2604 non-zero reflections. It was found that molecules in the β form were paired by approaching their carbonyl groups to each other at smaller distances than the sums of the van der Waals radii, while molecules in the α form were parallel to and separated at a distance of 3.60Å from each other in columns. There is some evidence for existence of other modifications in addition to the above two.

Key Words:

• Keywords: phenanthrenequinone, quinone, crystal structure, polymorphism, polymorphore