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Figure 5
The two types of stacks of semi­quinone radicals. (a) A Peierls-distorted stack of radical dimers (alternating longer and shorter interplanar distances). (b) A stack of equidistant radicals. Interplanar separations are indicated as A (short, <3.2 Å), B (long, >3.5 Å) and C (intermediate, <3.3 Å). The radicals displayed are tetra­chloro­semi­quinone anions, and the stacks were observed in two polymorphs of the salt with the N-methyl­pyridinium cation (Molčanov et al., 2016BB68).

IUCrJ
Volume 6| Part 2| March 2019| Pages 156-166
ISSN: 2052-2525
https://doi.org/10.1107/S2052252519000186