Trimethyltriazacyclohexane coordination chemistry of simple rare-earth metal salts.

Reactions of 1,3,5-trimethyl-triazacyclohexane (Metach) with common rare-earth metal iodide, chloride, and triflate salts were examined to determine the capacity of this inexpensive chelate to provide alternative precursors for THF-free reactions. The reaction of LaI(THF) and CeI(THF) with 1,3,5-trimethyl-triazacyclohexane in THF generated toluene soluble (Metach)LnI, 1-Ln, in which the Ln center has a tri-capped trigonal prismatic geometry with two eclipsed Metach rings. Reaction with NdI(THF) forms the analogous 1-Nd, but a different structure with one outer sphere iodide, [(Metach)NdI][I], 2-Nd, is also accessible and has a structure reminiscent of bent metallocenes. The reaction of LaCl and Metach forms the less soluble (Metach)LaCl, which has a structure analogous to 1-Ln with eclipsed Metach rings. The mono-ring yttrium complex, (Metach)YCl(THF), could be isolated from the reaction of YCl with Metach. Reactions of La(OTf) with Metach were sensitive to the presence of residual proton sources as exemplified by the isolation of {(Metach)La(μ-OH)(μ-OTf)}, 5-La, and [HMetach][(Metach)La-(OTf)], 6-La. SmI reacts with Metach to produce the Sm(II) complex, (Metach)SmI(THF), 7-Sm, but 2-Sm can also form in this reaction. Complexes of the larger 1,4,7-trimethyltriazacyclononane (Metacn) ligand, namely (Metacn)LaI(THF), (Metacn)YCl, and (Metacn)SmI(THF) were synthesized for comparison. Several examples of the protonated ligands with simple counteranions, [HMetach][X] (X = Cl, Br, I) and [HMetacn][OTf], were identified in the course of these studies.