Co-Crystal with Unusual High Z′ and Z′′ Values Derived from Hexamethylenetetramine and 4-fluorophenol (1/1)

The title co-crystal, 1,3,5,7-tetraazatricyclo[3.3.1.1 3,7]decane (HMTA, 1)–4-fluorophenol (4-FP) (1/1), C 6H 12N 4·C 6H 5FO, shows an unusual asymmetric unit that comprises eight independent molecules (Z′′ = 8), four for each component, with four formula units per asymmetric unit (Z′ = 4). In the molecular packing, each HMTA molecule bridges one 4-FP molecule via an O？H···N hydrogen bond to form a two-molecule aggregate. Differences can be observed between the bond lengths and angles of the independent HMTA and 4-FP molecules and those of the molecules in the aggregate. The C？N bonds exhibit different bond lengths in the tetrahedral cage-like structure of the HMTA molecules, but the largest differences between the molecular aggregates are in the bond lengths in the 4-fluorophenol ring. In the crystal, the HMTA and 4-FP molecules form two hydrogen-bonded (O？H···N, C？H···F and C？H···O) dimers of HMTA and 4-FP molecules, A···D and B···C inversion dimers, which generate enlarged R 8 8(34) ring motifs in both supramolecular structures. In both structures, the crystal packing also features additional C？H···F and C？H···O interactions. The A···D and B···C dimers are linked by additional C？H···F and C？H···O hydrogen bonds, forming columns along the a and b axes, respectively. The importance of the C？H···F interaction to the structure and crystal packing has been demonstrated. View Full-Tex