Synthesis of a large organometallic macrocycle comprising four Ga-Ga bonds and four bridging ferrocene dicarboxylato ligands

The reaction of tetrakis[bis(trimethylsilyl)methyl]digallane(4), 1, with 1,1'-ferrocenedicarboxylic acid afforded orange-red crystals of the macrocyclic compound 2 in a yield of 84%. 2 contains a large 32-atom heteracycle, which comprises four Ga-Ga single bands bridged by four 1,1'-ferroeenedicarboxylato ligands. The largest diameter of the molecule is about 2.5 nm. The redox-active Ga-Ga sites and ferrocene iron centers are all oxidized irreversibly within a narrow potential range.