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

LnCl(THF) (Ln = Y, La ÷ Nd, Sm ÷ Lu) readily react with the tridentate 1,3,5-trimethyl-1,3,5-triazacyclohexane (Metach) 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(Metach)], (Ln = Y, La ÷ Ho) or binuclear complexes [LnCl(Metach)], or [LnCl(Metach)(THF)] (Ln = Sm, Tb). Detailed analysis of the NMR data of [LnCl(Metach)] complexes with paramagnetic lanthanide ions showed that their structures remained unchanged in the toluene solution. A series of isomorphous complexes [LnCl(Metach)(Py)] (Ln = La, Sm, Tb, Er, Lu; Py = pyridine) have been obtained by the recrystallization of either mononuclear or binuclear complexes from pyridine.