The Insertion of Ruthenium into Porphyrins Revisited and Improved: Proof of Concept Results with a Ruthenium(II) Monocarbonyl Compound, and the Spectacular Effect of Propionic Acid

This contribution, that readdresses the insertion of the Ru II –CO fragment into model porphyrins (i.e. ruthenation), has a Janus character, with one speculative and one practical side. As a proof of concept we demonstrate that ruthenation of a porphyrin can be performed under relatively mild conditions using the Ru II monocarbonyl complex [Ru(CO)(dmso) 5 ][PF 6 ] 2 that – besides CO – features exclusively labile dmso ligands. Even though this finding might seem trivial, it is only the second example that uses a Ru II carbonyl for porphyrin ruthenation, the first one having been reported almost 50 years ago and then neglected. From a practical point of view, we show the spectacular effect of propionic acid as solvent for performing the ruthenation of neutral and anionic model porphyrins with Ru 3 (CO) 12 ( 1 ). This process turned out to be extremely efficient and advantageous in terms of both reaction rates and yields (e.g. 100 % ruthenation of TPP in 30 min at 140 °C) compared to the procedures described in the literature.