Controllable Formation of Heterotrimetallic Coordination Compounds: Systematically Incorporating Lanthanide and Alkali Metal Ions into the Manganese 12-Metallacrown-4 Framework

The inclusion of Ln(III) ions into the 12-MC-4 framework generates the first heterotrimetallic complexes of this molecular class. The controllable and deliberate preparations of these compounds are demonstrated through 12 crystal structures of the Ln(III)M(I)(OAc)(4)[12-MCMn(N)shiIII-4](H2O)(4)center dot 6DMF complex, where OAc is acetate, shi(3-) is salicylhydroximate, and DMF is N,N-dimethylformamide. Compounds 112 have M-I as Na-I, and Ln(III) can be Pr-III (1), Nd-III (2), Sm-III (3), Eu-III (4), Gd-III (5), Tb-III (6), Dy-III (7), Ho-III (8), Er-III (9), Tm-III (10), Yb-III (11), and Y-III (12). An example with M-I = K-I and Ln(III) = Dy-III is also reported ((DyK)-K-III(OAc)(4)[12-MCMn(N)shiIII-4](DMF)(4)center dot DMF (14)). When La-III, Ce-III, or Lu-III is used as the Ln(III) ions to prepare the Ln(III)Na(I)(OAc)(4)[12-MCMn(N)shiIII-4] complex, the compound Na-2(OAc)(2)[12-MCMn(N)shiIII-4](DMF)(6)center dot 2DMF center dot 1.60H(2)O (13) results. For compounds 112, the identity of the Ln(III) ion affects the 12-MCMn(N)shiIII-4 framework as the largest Ln(III), Pr-III, causes an expansion of the 12-MCMn(N)shiIII-4 framework as demonstrated by the largest metallacrown cavity radius (0.58 angstrom for 1 to 0.54 angstrom for 11), and the Pr-III causes the 12-MCMn(N)shiIII-4 framework to be the most domed structure as evident in the largest average angle about the axial coordination of the ring Mn-III ions (103.95 degrees for 1 to 101.69 degrees for 11). For 14, the substitution of K-I for Na-I does not significantly affect the 12-MCMn(N)shiIII-4 framework as many of the structural parameters such as the metallacrown cavity radius (0.56 angstrom) fall within the range of compounds 1-12. However, the use of the larger K-I ion does cause the 12-MCMn(N)shiIII-4 framework to become more planar as evident in a smaller average angle about the axial coordination of the ring Mn-III ions (101.35 degrees) compared to the analogous Dy-III/Na-I (7) complex (102.40 degrees). In addition to broadening the range of structures available through the metallacrown analogy, these complexes allow for the mixing and matching of a diverse range of metals that might permit the fine-tuning of molecular properties where one day they may be exploited as magnetic materials or luminescent agents.