Two-electron (2e-) transfer reactions for mono-metallic complexes of first-row transition metals are uncommon due to the tendency of these metals to proceed through sequential one-electron (1e-) transfer pathways. For this chemistry to be observed, structural changes upon electron transfer are often needed to shift the 1e- redox potentials to a condition of potential inversion where 2e- transfer becomes favorable. Nickel(II) dithiocarbamate complexes take advantage of these conditions to drive 2e- oxidation from NiII to NiIV. Here, we present electrochemical studies of NiII(dtc)2, where dtc- is N,N-diethyldithiocarbamate, as a function of solvent and addition of Lewis acids and bases. These studies have revealed mechanistic information about how four-coordinate NiII(dtc)2 undergoes 2e- oxidation to [NiIV(dtc)3]+ and vice versa. Solvent dependence shows that coordination of the solvent to intermediate [NiIII(dtc)2]+ species is greatly important in facilitating the conversion from NiII(dtc)2 to [NiIV(dtc)3]+. This is shown even more clearly with the addition of derivatized pyridines to control the coordination strength of pyridine to [NiIII(dtc)2]+, which in turn affects the lifetime of the intermediate oxidation state before proceeding to [NiIV(dtc)3]+. Two-electron reduction of [NiIV(dtc)3]+ to NiII(dtc)2 usually proceeds through two 1e- transfer steps due to the stability of the NiIII(dtc)3 species, however, we show that the addition of simple Lewis acids such as ZnII results in a remarkable 2e- concerted reduction. We believe that ZnII ions are able to coordinate to dtc- ligands in the secondary sphere whereby they assist in the removal of these ligands which is required for reduction of [NiIV(dtc)3]+ to NiII(dtc)2. Overall, these studies provide insight into how we may be able to control 1e- versus 2e- redox chemistry using coordination environment around a first-row transition metal.

Mechanistic insights into two-electron transfer reactions with first-row transition metal complexes

Macromolecular Chemistry: The Second Century

[Author Benefits](https://scimeetings.acs.org/?utm_source=pubs_content_marketing&utm_medium=website&utm_campaign=0320_MCF_NPI_Launch_Spring_Homepage&ref=pubs_content_marketing)

[How to use SciMeetings](https://storage.googleapis.com/dl.morressier.com/acs/SciMeetings-ACSSpring2020-HowToGuide_M3020-Final.pdf)

[Frequently Asked Questions](https://storage.googleapis.com/dl.morressier.com/acs/SciMtng_ACSNMSp2020_FAQ_M3120_Final.pdf)

ACS Spring 2020 National Meeting & Expo

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.