High-nuclearity metal-organic nanospheres: a Cd66 ball.

Reaction of H3L with Cd(NO3)2·4H2O in DMF at 150 °C for 3 days affords the metal–organic nanosphere [Cd66(μ3-OH)28(μ3-O)16(μ5-NO3-O,O,O′,O′,O″,O″)12(L)20(μ2-DMF)12⊂(DMF)9]. The cluster is composed of a spherical shell of 66 Cd(II) cations bridged by 28 μ3-hydroxide, 16 μ3-oxo, and five μ5-NO3– anions surrounded by a shell of 20 tripodal capping ligands (L) and 12 DMF ligands. The 66 Cd(II) cations and 12 NO3– anions form a polydeltahedron that has 78 vertices [Cd(II) or NO3–] (V), 228 edges (E), and 152 triangular faces (F), giving it an Euler characteristic (χ) of 2 (χ = V + F – E). Reaction of H3L with Cd(NO3)2·4H2O at lower temperatures or with CdCl2 affords coordination polymer frameworks instead of nanospheres.