Triggering Electron Transfer in Co(I) Dimers: Computational Evidences for a Reversible Disproportionation Mechanism

An inner‐sphere disproportionation mechanism of the Co(I) precursor CoCl(PPh3)3 is described through a Density Functional Theory study. The essential role of oleylamine in this process is unravelled. A detailed analysis of the electronic structure of Cobalt dimers of the general formula Co2Cl2Ln (L=NH3 and PH3) demonstrates that electron transfer is triggered by asymetric coordination of amine and phosphine to stabilize a mixed‐valence Co(II)−Co(0) dimer. This is consistent with the HSAB statement that both amine and phosphine ligands are required to stabilize the reaction products, respectively Co(II) and Co(0) centers. We propose a quasi‐athermic multi‐step disproportionation mechanism with low activation barriers where the electron transfer goes through simple ligand exchanges between Co. Inner‐sphere electron transfer in dimers of Co(I) precursor CoCl(PPh3)3 is triggered by simple ligand exchanges between the Co centers, leading an asymetric coordination of amines and phosphines to stabilize, according to HSAB principles, a mixed‐valence Co(II)−Co(0) dimer.