Tridentate Nitrogen Ligand as a Tool for the Construction of Well-Defined Rare Earth Trichloride Complexes.

LnCl 3 (THF) 3 (Ln = Y, La ÷ Nd, Sm ÷ Lu) readily react with the tridentate 1,3,5-trimethyl-1,3,5-triazacyclohexane (Me 3 tach) ligand to form mono- or binuclear lanthanide trichloride complexes, depending on the stoichiometry of the reaction and the ionic radius of the metal: mononuclear pseudosandwich [LnCl 3 (Me 3 tach) 2 ], (Ln = Y, La ÷ Ho) or binuclear complexes [Ln 2 Cl 6 (Me 3 tach) 3 ], or [LnCl 3 (Me 3 tach)(THF)] 2 (Ln = Sm, Tb). Detailed analysis of the NMR data of [LnCl 3 (Me 3 tach) 2 ] complexes with paramagnetic lanthanide ions showed that their structures remained unchanged in the toluene solution. A series of isomorphous complexes [LnCl 3 (Me 3 tach)(Py) 2 ] (Ln = La, Sm, Tb, Er, Lu; Py = pyridine) have been obtained by the recrystallization of either mononuclear or binuclear complexes from pyridine. Complexes of terbium and europium ions with the Me 3 tach ligand exhibit relatively high quantum yields of metal-centered luminescence (0.39 and 0.32, respectively).