2,9-Di­chloro-5,12-di­hydro­quino­[2,3-b]­acridine-7,14-dione

The title compound, C₂₀H₁₀Cl₂N₂O₂, is an industrially important red pigment. The mol­ecule has inversion symmetry. The mol­ecule is not entirely planar, as shown by the dihedral angle of 176.7 (3)° between the planes of the benzene ring at the center and that at the extremity. The mol­ecules are stacked in a `hunter's fence' fashion (i.e. when viewed from the side, the mol­ecules cross one another with an angle of about 50° in a grid-like structure) along the a axis.

2,9-Dichloro­quino[2,3-b]acridine-7,14(5H,12H)-dithione dimethyl­formamide disolvate

The title compound, C₂₀H₁₀Cl₂N₂S₂·2C₃H₇NO, is a dimethyl­formamide (DMF) disolvate of DTQ-Cl, which is a thio­nated pigment derivative of 2,9-dichloro­quinacridone. The DTQ-Cl mol­ecule is centrosymmetric and entirely planar. Two DMF mol­ecules are hydrogen-bonded to DTQ-Cl, through the NH group of DTQ-Cl and the O atom of DMF. The mol­ecular plane of DMF is twisted with respect to the skeleton of DTQ-Cl by 21.4 (1)°.

The monoclinic form of 2,9-dichloro-5,12-dihydro­quino[2,3-b]acridine-7,14-dithione dimethyl­acetamide disolvate

The title compound, C₂₀H₁₀Cl₂N₂S₂·2C₄H₉NO, is a dimethyl­acetamide (DMA) disolvate of DTQ-Cl, which is a thio­nated derivative of a 2,9-dichloro­quinacridone pigment. The compound shows polymorphism and this paper reports the monoclinic form (space group P2₁/c, Z = 4). Two DMA mol­ecules are hydrogen bonded via their O atoms to the NH group of DTQ-Cl. The mol­ecular planes of the two DMA mol­ecules are asymmetrically twisted with respect to the DTQ-Cl skeleton by 11.65 (8) and 31.58 (9)°.

The triclinic form of 2,9-dichloro-5,12-dihydro­quino[2,3-b]acridine-7,14-dithione dimethyl­acetamide disolvate

The title compound, C₂₀H₁₀Cl₂N₂S₂·2C₄H₉NO, is a dimethyl­acetamide (DMA) disolvate of DTQ-Cl, which is a thio­nated derivative of a 2,9-dichloro­quinacridone pigment. The compound shows polymorphism and this paper reports the triclinic form (space group P, Z = 1). The DTQ-Cl mol­ecule is centrosymmetric and planar, while the DMA mol­ecule is orientationally disordered. Two symmetry-related DMA mol­ecules are hydrogen bonded via their O atoms to the NH groups of DTQ-Cl. The mol­ecular plane of DMA is twisted with respect to the DTQ-Cl skeleton by 73.6 (1)°.

2,9-Di­chloro-5,12-di­hydro­quino­[2,3-b]­acridine-7,14-dione (red phase)

The title compound, C₂₀H₁₀Cl₂N₂O₂, is one of the quinacridone derivatives known as a red pigment. The mol­ecule has inversion symmetry. The quinacridone molecules are connected by bifurcated N—H...O hydrogen bonds along [110] to form a two-dimensional hydrogen-bond network.