Topochemistry. Part XIII. The crystal structure of 2,3,5,6-tetramethyl-1,4-benzoquinone (duroquinone)

Abstract

The crystal structure of 2,3,5,6-tetramethyl-1,4-benzoquinone has been analysed from full three-dimensional Cu Kα counter data. The triclinic structure consists of two sets of symmetry-unrelated planar molecules centred at (000) and (½00), whose bond lengths, after correction for thermal vibration, agree to within their e.s.d.: CC, 1·341 Å; C–CMe, 1·492 Å; C–CH₃, 1·514 Å; CO, 1·232 Å. Bond lengths determined here agree well with those measured in other p-benzoquinones, except for the [graphic omitted] bond, which is significantly longer by ca. 0·02 Å than the corresponding bond substituted by hydrogen or chlorine.

The two sets of molecules form a single stack along [100] which is nearly normal to the molecular planes. Successive molecules along the stack, separated by a/2 = 3·47 Å, are rotated by 86·5 and 93·5° about the [100] direction.