10-(4-Fluorophenyl)-3,3,6,6,9-penta-methyl-3,4,6,7,9,10-hexahydro-acridine-1,8(2H,5H)-dione and 10-(4-fluorophenyl)-3,3,6,6-tetra-methyl-9-propyl-3,4,6,7,9,10-hexa-hydroacridine-1,8(2H,5H)-dione

10-(4-Fluorophenyl)-3,3,6,6,9-pentamethyl-3,4,6,7,9,10-hexa- hydroacridine- 1,8(2H,5H)-dione, C24H28FNO2, (I), crystallizes with two crystallographical ly independent molecules (which differ slightly in conformation), while 10- (4-fluorophenyl)-9-propyl-3,3,6,6-tetramethyl-3,4,6,7,9,10-hexahydro- acrid ine-1,8(2H,5H)-dione, C26H32FNO2, (II), crystallizes with one molecule per asymmetric unit. In both structures, the central ring in the acridine moiet y is in a sofa conformation, while the outer rings adopt intermediate half- chair/sofa conformations. The central pyridine ring is orthogonal to the su bstituted phenyl ring. In both structures, the packing of the crystal is st abilized by C-H . . .O intermolecular hydrogen bonds.