Synthesis and Structure of 2,5-Bis[N-(2,6-mesityl)iminomethyl]pyrrolylcobalt(II): Evidence for One-Electron-Oxidized, Redox Noninnocent Ligand Behavior.

The title complex Co(Mes2pyr)Cl2 is prepared from CoCl2 and (Mes2pyr)H. Instead of the expected (Mes2pyr)CoCl complex, a complex with formula (Mes2pyr)CoCl2 is isolated wherein the angle strain of the Mes2pyr ligand results in metal ligation by only two of the three ligand donor atoms. Careful examination of structural, spectroscopic, and magnetic features indicates this compound is best described as a complex of high-spin Co(II) with a neutral radical ligand.