Air-Stable Dinuclear Complexes of Four-Coordinate Zn and Ni Ions with a Radical Bridge: A Detailed Look at Redox Activity and Antiferromagnetic Coupling.

Air-stable dinuclear complexes [(bmsab)Ni(tmsab)Ni(bmsab)] and [(bmsab)Zn(tmsab)Zn(bmsab)] (bmsab = bis(methanesulfoneamido)benzene, tmsab = tetra(methanesulfonamido)benzene) were prepared via a synthetic route based on heteroleptic precursor complexes. The new complexes combine a distorted tetrahedral coordination environment with an open-shell bridging ligand. The Zn species was subjected to a detailed investigation of the (spectro-)electrochemical processes. The Ni species is a rare example of a complex that combines strong exchange coupling ( > 440 cm) with pronounced positive zero-field splitting ( = +72 cm). Combining SQUID magnetometry and (HF)EPR spectroscopy with ab initio calculations allowed for accurate quantification of the exchange interaction.