A Homologous Series of Cobalt, Rhodium, and Iridium Metalloradicals

We herein present a series of d7 trimethylphosphine complexes of group 9 metals that are chelated by the tripodal tetradentate tris­(phosphino)­silyl ligand [SiPiPr3]H ([SiPiPr3] = (2-iPr2PC6H4)3Si–). Both electron paramagnetic resonance (EPR) simulations and density functional theory (DFT) calculations indicate largely metalloradical character. These complexes provide a rare opportunity to compare the properties between the low-valent metalloradicals of the second- and third-row transition metals with the corresponding first-row analogues.