Versatile Coordination Modes of Multidentate Neutral Amine Ligands with Group 1 Metal Cations

This work comprehensively investigated the coordination chemistry of a hexa-dentate neutral amine ligand, namely, N,N',N"-tris-(2-N-diethylaminoethyl)-1,4,7-triaza-cyclononane (DETAN), with group-1 metal cations (Li⁺, Na⁺, K⁺, Rb⁺, Cs⁺). Versatile coordination modes were observed, from four-coordinate trigonal pyramidal to six-coordinate trigonal prismatic, depending on the metal ionic radii and metal's substituent. For comparison, the coordination chemistry of a tetra-dentate tris-[2-(dimethylamino)ethyl]amine (Me₆Tren) ligand was also studied. This work defines the available coordination modes of two multidentate amine ligands (DETAN and Me₆Tren), guiding future applications of these ligands for pursuing highly reactive and elusive s-block and rare-earth metal complexes.