Heterodimetallic Compounds Assembled from Ferrocenedicarboxylato and Ferrocenecarboxylato Ligands

Heteropolynuclear organometallic compounds have been constructed by using two kinds of ferrocene-based ligands,
1,1‘-ferrocenedicarboxylic acid (H2L1) and ferrocenecarboxylic acid (HL2). Reactions the ligand H2L1 with copper(II)
and nickel(II) salts, in the presence of pyridine, give a tetranuclear Cu2Fe2 mixed-metallic box Cu2L12(Py)2(DMF)2(H2O)2 (1) and a tetranuclear heterobimetallic helix Ni2L12(Py)4(H2O) (2), respectively. In these complexes, the
ferrocene moieties show cisoid conformations which lead to the formation of the finite coordination geometry, i.e.
to molecular complexes. Interactions of the ligand H2L1 with lanthanide ions afford two-dimensional networks
[La2L13(CH3OH)4]∞ (3), [Eu2L13(H2O)5]∞ (4), and [Gd2L13(CH3OH)2(H2O)3]∞ (5), respectively, in which transoid
conformations of the ferrocene moiety provide opportunities to form infinite 2-D networks. It is suggested that the
conformational freedom of the ferrocene moiety makes the ligand L1 display different conformations and coordination
modes in these complexes. In addition, the π···π interactions related to the ferrocene moieties were also found
to stabilize the supramolecular architectures in the solid state. As a comparison, reaction of lanthanide ions with
the ligand HL2 resulted in three isostructural heterodinuclear windmill-shaped compounds Ln2L26(CH3OH)2(H2O)5
[Ln = La (6), Eu (7), and Gd (8)] by simply diffusing the solutions of lanthanide ions into the mixture of HL2 and
NaOH, respectively. Electrochemical properties of the ferrocene-containing complexes 1−8 are also investigated in
the solution or solid state.