Effects of Solvents on Reaction Products: Synthesis of Endohedral Metallofullerene Oxazoline and Epoxide.

Herein, we performed the reactions of M3N@Ih-C80 (M = Sc and Lu) with the methanol (CH3OH) solution of TBAOH (note that both CH3O- and OH- are nucleophiles) in benzonitrile (PhCN) and dimethylformamide, respectively. It is found that OH- ions rather than CH3O- ions selectively attacked the fullerene cage to form the M3N@C80--O- intermediate. Although the fullerene cage is initially attacked by OH- in both PhCN and DMF solvents, the products are quite different. In PhCN, two isomeric Sc3N@Ih-C80 fullerooxazoline heterocyclic products (1 and 2) were synthesized. Whereas, in DMF, an epoxide of Lu3N@Ih-C80 (3) was obtained. The preference for fullerooxazoline formation over that of fullerene epoxy in PhCN is well explained by density functional theory calculations. Plausible reaction mechanisms for the formation of metallofullerene oxazoline and epoxide were proposed based on the experimental and theoretical results.

Diversity of Metal-Fullerene Framework Structures Regulated by Metal Salts.

Taking into account the diversity of fullerene ligands and metal salts, metal-fullerene frameworks (MFFs) present a variety of structures. Currently, the structural control of MFFs mainly relies on the design and synthesis of fullerene ligands, while the influence of metal building units on the structures has been rarely studied. The present work represents a systematical investigation of fullerene-linked supramolecular architectures incorporating different metal salts. Treatment of a bidentate N,N-donors fullerene ligand (L1) with six metal salts ([Zn(NO3)2·6H2O, Cd(NO3)2·4H2O, Cu(NO3)2·3H2O, Cu(OAc)2·H2O, FeCl2·4H2O and FeCl3·6H2O]) produced six one-dimensional MFFs, i.e., ZnL1(NO3)2(H2O)2 (1), CdL1(NO3)2 (2), Cu(L1)(H2O)2(NO3)2 (3), CuL1(OAc)(CH3O) (4), FeL1Cl2 (5) and FeL1Cl2(FeCl4) (6). Compounds 1-3, built with nitrates with different metal centers (M(NO3)2, M = Zn, Cd, Cu), present a 1D stair-like, 1D zigzag, and 1D linear chain structure, respectively. Compound 4, synthesized with another Cu(II) salt, Cu(OAc)2, displays a dinuclear Cu-Cu connected 1D stair-like chain structure, rather than the single Cu linked 1D linear chain obtained from Cu(NO3)2. Compounds 5 and 6, assembled from iron chloride of different oxidation states (Fe(II)Cl2 and Fe(III)Cl3) reveal a 1D zigzag and a 1D stair-like chain structure, respectively. The results demonstrate the significant influences of metal salts on the structures of metal-fullerene frameworks.