Flavosemiquinone model systems. Part 3. Molecular and crystal structure of the cation radical salt 1,4,6,7-tetramethylquinoxalinium triiodide. Journal of the Chemical Society, Perkin Transactions 2: Physical Organic Chemistry, 3:343--345, 1993. [PUMA: crystal radical triiodide tetramethylquinoxalinium model triiodide;flavosemiquinone cation structure;mol structure]