1,4,7-Triazacyclononane Ligands Bearing Tertiary Alkyl Nitrogen Substituents

The first synthesis of 1,4,7-tri-tert-butyl-1,4,7-triazacyclononane ( t Bu3tacn) and its adamantyl analog Ad3tacn are described. CrII, MnII, FeII, CoII, NiII, and CuI compounds of t Bu3tacn are reported: the steric properties of this ligand enforce four-coordinate geometries except in the case of five-coordinate CrII, enabling design of pseudotetrahedral compounds bearing this tridentate redox-inert ancillary ligand.