“…Ru II (Ariel et al, 1984), Ru III (James et al, 1984), Ru IV (Maeda et al, 2015) or Ru VI (Katsunori et al, 2012), and it is able to coordinate one or two small axial ligands, such as aqua, hydroxide, dinitrogen, nitrite, nitrosyl, carbonyl, methanol, ethanol, tetrahydrofuran, pyridine and many others, as can be found from a search in the Cambridge Structural Database (ConQuest, Version 1.18 with updates; Groom et al, 2016), which gave 225 hits. The structural diversity of ruthenium complexes, which can also form metal-metal bonds (Collman et al, 1984), offers an opportunity to use them in the design of multifunctional supramolecular assemblies (Mamardashvili et al, 2013).…”