The Versatile Ruthenium(ii/iii) Tetraazamacrocycle Complexes and Their Nitrosyl Derivatives

Macrocyclic ligands are relevant because of the properties they impart to transition metal complexes, such as enhanced thermodynamic stability and slowed substitution kinetic behavior. Here, we address issues not previously reviewed, revisit others, present new results, and review and discuss the results obtained in the last decade for ruthenium(II/III) complexes with tetraazamacrocycles (mac) such as cyclam (1,4,8,11-tetraazacyclotetradecane), [RuL1L2(mac)]q+ with emphasis on nitrosyls. Topics include synthesis, macrocycle functionalization, structure, spectroscopy, photochemistry, reactivity, density functional theory calculations, and biological properties. [RuL1L2(mac)]q+ complexes exhibit a rich chemistry, sometimes unusual, which depends on macrocycle ring size, the presence of N- or C-pendant groups, metal oxidation state, electronic structure, and the nature of L1 and L2. These same features can be used to tune the properties of the complexes leading to potential applications in diverse fields.