PLANARITY OF NITROSUBSTITUTED PHENOTHIAZINES

The structures of three nitro-substituted phenothiazines [1,3,4-triflu oro-2-nitrophenothiazine, -chlorobutyl)-1,3,4-trifluoro-2-nitrophenoth iazine and 10-(4-chlorobuthyl)-3-nitrophenothiazine] have been determi ned. The first of these red compounds forms infinite stacks in the sol id state, in which donor and acceptor regions of the approximately pla nar molecules alternate. The molecules of the other two compounds, whi ch have folded, or 'butterfly', conformations in the solid state, do n ot form stacks, presumably the bulky chlorobutyl substituents cannot b e accommodated. The very dark color of solid 3-nitrophenothiazine sugg ests the presence of extended molecular stacks, but crystals suitable for a structure determination could not be obtained.