Ferrocene-1,1'-dicarboxylic acid as a building block in supramolecular chemistry: supramolecular structures in one, two and three dimensions.
The supramolecular structures have been determined for nine adducts formed between organic diamines and ferrocene-1,1'-dicarboxylic acid. In the salt-like 1:1 adduct (1) formed with methylamine, the supramolecular structure is one-dimensional, whereas in the 1:1 adducts formed with 1,4-diazabicyclo[2.2.2]octane, (2), and 4,4'-bipyridyl, (4), and in the hydrated 2:1 adduct (3) formed with morpholine, the hard hydrogen bonds form one-dimensional structures, which are expanded to two dimensions by soft C-H...O hydrogen bonds. The hard hydrogen bonds generate two-dimensional structures in the 2:1 adduct (5) formed with octylamine, where the ferrocene component lies across a centre of inversion, in the 1:1 adduct (6) formed with piperidine and in the tetrahydrofuran-solvated 1:1 adduct (7) formed with di(cyclohexyl)amine. In the 2:3 adduct (8) formed by tris-(2-aminoethyl)amine, and in the 2:1 adduct (9) formed with 2-(4'-hydroxyphenyl)ethylamine (tyramine), where Z' = 1.5 in space group P-1, the hard hydrogen bonds generate three-dimensional structures. No H transfer from O to N occurs in (4) and only partial transfer of H occurs in (2); in (1), (6) and (7), one H is transferred to N from each acid molecule, and in (3), (5), (8) and (9), two H are transferred from each acid molecule.