Packing considerations of bis-dimedone derivatives

We have determined the crystal structures of 2,2'-(4-fluorophenyl)methylene bis(3-hydroxy-5,5-dimethyl-2-cyclohexen-1-one), C23H27FO4, (I), 2,2'-(4-chl orophenyl)methylenebis-(3hydroxy-5,5-dimethyl-2-cyclohexen-1-one), C23H27Cl O4, (II), 2,2'-(4-hydroxyphenyl)methylenebis(3-hydroxy-5,5-dimethyl-2-cyclo hexen-1-one), C23H28O5, (III), 2,2'-(4-methylphenyl)methylenebis(3-hydroxy- 5,5-dimethyl-2-cyclohexen-1-one), C24H30O4, (IV), 2,2'-(4-methoxyphenyl)met hylenebis(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-cycloh exen-1-one), C25H33NO4, (VI). Structures (III) to (VI) of these bis-dimedon e derivatives show nearly the same packing pattern irrespective of the diff erent substituent in the para position of the aromatic ring. However, (II) does not rt 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 r ing. On the other hand, (I) shows a similar packing pattern to bis(2-hydrox y-4,4-dimethyl-6-oxo-1-cyclohexenyl)phenylmethane, a compound containing an aromatic ring without any substituent and with Z' = 2.