Packing considerations of bis-dimedone derivatives

We have determined the crystal structures of 2,2′-(4-fluoro­phenyl)­methyl­enebis(3-hydroxy-5,5-di­methyl-2-cyclo­hexen-1-one), C₂₃H₂₇FO₄, (I), 2,2′-(4-chloro­phenyl)­methyl­enebis(3-hy­droxy-5,5-dimethyl-2-cyclo­hexen-1-one), C₂₃H₂₇ClO₄, (II), 2,2′-(4-hydroxy­phenyl)­methyl­enebis(3-hydroxy-5,5-di­methyl-2-cyclo­hexen-1-one), C₂₃H₂₈O₅, (III), 2,2′-(4-methyl­phenyl)­methyl­enebis(3-hydroxy-5,5-di­methyl-2-cyclo­hexen-1-one), C₂₄H₃₀O₄, (IV), 2,2′-(4-methoxy­phenyl)­methyl­enebis(3-hy­droxy-5,5-di­methyl-2-cyclo­hexen-1-one), C₂₄H₃₀O₅, (V), and 2,2′-(4-N,N′-di­methyl­amino­phenyl)­methyl­enebis(3-hydroxy-5,5-di­methyl-2-cyclo­hexen-1-one), C₂₅H₃₃NO₄, (VI). Structures (III) to (VI) of these bis-dimedone derivatives show nearly the same packing pattern irrespective of the different substituent in the para position of the aromatic ring. However, (II) does not fit into this scheme, although the Cl atom is a substituent not too different from the others. The different packing of the fluoro compound, (I), can be explained by the fact that it crystallizes with two mol­ecules in the asymmetric unit, which show a different conformation of the dimedone ring. On the other hand, (I) shows a similar packing pattern to bis(2-hydroxy-4,4-di­methyl-6-oxo-1-cyclo­hexenyl)­phenyl­methane, a compound containing an aromatic ring without any substituent and with Z′ = 2.