Stimulation of Redox-Induced Electron Transfer by Interligand Hydrogen Bonding in a Cobalt Complex with Redox-Active Guanidine Ligand.

ABSTRACT: Octahedrally coordinated cobalt(II) complexes with a redox-active bisguanidine ligand and acac co-ligands were synthesized and their redox chemistry analysed in detail. The N-H functions in a bisguanidine ligand with partially alkylated guanidino groups form N-H⋅⋅⋅O hydrogen bonds with the acac co-ligands, thereby massively influencing the redox chemistry. For all complexes, the first one-electron oxidation is metal-centred, leading to Co^III complexes with neutral bisguanidine ligand units. Further one-electron oxidation is ligand-centred in the case of Co-bisguanidine complexes with fully alkylated guanidino groups, giving Co^III complexes with radical monocationic bisguanidine ligands. On the other hand, the hydrogen-bond strengthening upon oxidation of the Co-bisguanidine complex with partially alkylated guanidino groups initiates metal reduction (Co^III →Co^II ) and two-electron oxidation of the guanidine ligand, providing the first example for the stimulation of redox-induced electron transfer by interligand hydrogen bonding.

SUBMITTER: Lohmeyer L 

PROVIDER: S-EPMC8252010 | biostudies-literature | 2021 Apr

REPOSITORIES: biostudies-literature