N-macrocyclic complexes of ruthenium(II) and ruthenium(III)

Article abstract of DOI:10.1021/ic50223a019

The following new macrocycle ligand complexes of ruthenium have been synthesized: [Ru(mac)Cl₂]Cl (mac = 2,3-dimethyl-1,4,8,11-tetraazacyclotetradecane (I), 1,4,8,12-tetraazacyclopentadecane (II), and 1,5,9,13-tetraazacyclohexadecane (III)). Compounds II and III, along with the previously reported [Ru([14]aneN₄)Cl₂]Cl ([14]aneN₄ = 1,4,8,11-tetraazacyclotetradecane) comprise a series differing in the ring size of the macrocycle. Changes in ring size do not appreciably affect the charge-transfer electronic spectra or the Ru-Cl infrared stretching vibration. A small cathodic shift in the formal potential of the Ru(mac)Cl₂^+/0 couple and a decrease in the chloride affinity of the Ru(II) is observed as the ring size is increased. The structure of [Ru([14]aneN₄)Cl₂]Br was determined from three-dimensional X-ray diffraction analysis, and the trans geometry of the chloro ligands was verified. Revealed in the structure are nonbonded interactions within the cation between the chloro ligands and the nitrogen-bound hydrogen atoms, which affect the charge-transfer spectra of the Ru(III) form.