Synthesis and structural characterization of binuclear half-sandwich iridium, rhodium and ruthenium complexes containing 4,4'-dipyridyldisulfide (4DPDS) ligands.

Reactions of half-sandwich iridium and rhodium complexes [CpMCl2]2 (1a: M = Ir, 1b: M = Rh) and the half-sandwich ruthenium complex [(p-cymene)RuCl2]2 (1c) with 4DPDS gave the corresponding binuclear complexes [{CpMCl2]2}(m-4DPDS) (2a: M = Ir, 2b: M = Rh) and [{(p-cymene)RuCl2]2}(m-4DPDS) (2c), which can be converted into binuclear metallamacrocycles. The metallamacrocycles [Cp*M(m-4DPDS)Cl]2(2+) (3a: M = Ir, 3b: M = Rh) and [(p-cymene)Ru(m-4DPDS)Cl]2(2+) (3c) are composed of two half-sandwich units and two 4DPDS ligands with the same chirality. The macrocycle 3c is chiral and changes its shape slightly depending on the guests accommodated above and below the cavities.