A supramolecular analog of cyclohexane sustained by aromatic C-H center dot center dot center dot pi interactions between ferrocene moieties: molecular packing of ferrocene-containing thiosemicarbazato metal complexes

Novel supramolecular cyclohexane-like structures, [NiL2] (1) and [ZnL2] (2) (HL=acetylferrocenyl thiosemicarbazone), have been constructed by self-ass embly of ferrocene moieties via aromatic C-H ...pi interactions. The nickel (ii) atom in 1 is coordinated in a distorted square-planar cis configuratio n with two ferrocene-containing ligands positioned on the same side. One of the ferrocene moieties interacts with symmetry-related species to form a s upramolecular arrangement that is topologically equivalent to cyclohexane, but in which edge-to-face C-H ...pi interactions between ferrocene moieties serve the same structural functions as the C-C bonds in cyclohexane. The z inc(ii) atom in 2 is coordinated in a tetrahedral geometry with two equival ent Zn-S and Zn-N bonds. Each ferrocene moiety interacts with symmetry-rela ted species using C-H ...pi interactions to form a two-dimensional cyclohex ane-like network. Powder X-ray diffraction analyses of complexes 1 and 2, t ogether with the palladium(ii) complex [PdL2] (3), copper(ii) complex [CuL2 ] (4), and cobalt(ii) complex [CoL2] (5) reveal that the supramolecular cyc lohexane-like aggregation is robust enough to be exchanged from one network to another. All the results indicate that although C-H ...pi interactions have energies only in the 2-20 kJ mol(-1) range, these interactions are dir ectional enough in combination that the orientation of molecules in the sol id can be predicted with a reasonable degree of accuracy.