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

The inclusion of LnIII 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 LnIIIMI(OAc)4[12-MCMnIII(N)shi-4]­(H2O)4·6DMF complex, where OAc– is acetate, shi3‑ is salicylhydroximate, and DMF is N,N-dimethylformamide. Compounds 1–12 have MI as NaI, and LnIII can be PrIII (1), NdIII (2), SmIII (3), EuIII (4), GdIII (5), TbIII (6), DyIII (7), HoIII (8), ErIII (9), TmIII (10), YbIII (11), and YIII (12). An example with MI = KI and LnIII = DyIII is also reported (DyIIIK­(OAc)4[12-MCMnIII(N)shi-4]­(DMF)4·DMF (14)). When LaIII, CeIII, or LuIII is used as the LnIII ions to prepare the LnIIINaI(OAc)4[12-MCMnIII(N)shi-4] complex, the compound Na2(OAc)2[12-MCMnIII(N)shi-4]­(DMF)6·2DMF·1.60H2O (13) results. For compounds 1–12, the identity of the LnIII ion affects the 12-MCMnIII(N)shi-4 framework as the largest LnIII, PrIII, causes an expansion of the 12-MCMnIII(N)shi-4 framework as demonstrated by the largest metallacrown cavity radius (0.58 Å for 1 to 0.54 Å for 11), and the PrIII causes the 12-MCMnIII(N)shi-4 framework to be the most domed structure as evident in the largest average angle about the axial coordination of the ring MnIII ions (103.95° for 1 to 101.69° for 11). For 14, the substitution of KI for NaI does not significantly affect the 12-MCMnIII(N)shi-4 framework as many of the structural parameters such as the metallacrown cavity radius (0.56 Å) fall within the range of compounds 1–12. However, the use of the larger KI ion does cause the 12-MCMnIII(N)shi-4 framework to become more planar as evident in a smaller average angle about the axial coordination of the ring MnIII ions (101.35°) compared to the analogous DyIII/NaI (7) complex (102.40°). 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.