For simplicity reasons, only one topological isomer of this system was considered, bearing the coordinated olefin, a CO ligand and the carbene fragment in the equatorial plane. Secondly, we adopted a tridentate pincer-type carbene system with a benzene backbone (2-Mn) as devised by Solans-Monfort and coworkers. The latter work concluded that Fe=CH 2 fragments and metallacyclobutanes are ideally stabilized in the singlet state utilizing ECE pincer ligands (E = NHC, PR 2 ) with a strong σ-donor present in the central position.