Facile carboxylate ligand variation of heterotrimetallic 12-metallacrown-4 complexes

Abstract

Single crystal X-ray structures are presented for three 12-metallacrown-4 complexes, ErIIINa(L)4[11-MCMnIII(N)shi-4], where L is trimethylacetate (OTMA), benzoate (OBen), or salicylate (OSal), MC is metallacrown, and shi3− is salicylhydroximate: ErIIINa(OTMA)4[12-MCMnIII(N)shi-4](H2O)3.73(DMF)0.27·7.45DMF·1.47H2O, 1, ErIIINa(OBen)4[12-MCMnIII(N)shi-3](H2O)4·4DMF·0.87H2O, 2, and ErIIINa(OSal)4[12-MCMnIII(N)shi-4](H2O)3.54(DMF)0.73·4DMF·0.24H2O, 3, where DMF is N,N-dimethylformamide. Compounds 1–3 demonstrate the facile ligand variation of a self-assembled supramolecular coordination complex containing three different metal types. In all three structures, the monoanion carboxylate ligands serve as bridges between the central ErIII ion and the ring MnIII ions. The structures of 1–3 are all domed towards the side of the central Na+ ion, and the 12-MC-4 frameworks of 1–3 are very similar regardless of the monoanion carboxylate bridge, as the metallacrown cavity radii of 1–3 are 0.55Å, 0.54Å, and 0.55Å, respectively. In addition, the cross cavity measurements indicate that the metallacrown frameworks are not significantly altered by the presence of different monoanion carboxylate ligands as the MnIII–MnIII cross cavity distances for 1–3 are 6.52Å, 6.51Å, and 6.49Å, respectively, and the oxime oxygen–oxime oxygen cross cavity distances for 1–3 are 3.71Å, 3.68Å, and 3.69Å, respectively. The conservation of the 12-MC-4 framework among the different structures will be important when assessing the physical and chemical properties of this class of molecules.