A new crystal structure of catena-(bis((µ4-cubane-1,4-dicarboxylato)-(N-methyl-2-pyrrolidone)-zinc(II)) N-methyl-2-pyrrolidone solvate) (1) was prepared by solvothermal method. The crystal structure of the compound was analyzed by single-crystal X-ray diffraction. It has a P1 space group, with lattice parameters a = 10.7190(4) Å, b = 10.8245(5) Å, c = 10.8403(8) Å, α = 80.291(5)°, β = 70.0015(5)°, γ = 77.531(4)°, V = 1147.97(12) Å3. The secondary building units of 1 consist of 2 central Zn ions, coordinated by 4 carboxylate groups in a bis-monodentate way, forming a square planar configuration of Zn2(CO2)4, known as paddle-wheel units. The paddle-wheels are connected by cubane-1,4-dicarboxylic acid linkers at the edges, resulting in a two-dimensional coordination polymer with a square lattice (sql) underlying network topology. The axial sites of the zinc atoms are occupied by N-methyl-2-pyrrolidone molecules. In this new crystal structure the two-dimensional polymer planes are interstacked by weak dispersion bonds. The axial N-methyl-2-pyrrolidone solvent molecules determine the distances of planar polymer planes. The thermal properties of this new structure were studied by thermogravimetry/mass spectrometry in inert atmosphere. It was found, that the organic linkers in the framework structure do not decompose below 200 °C. The stochiometry of the activated compound is Zn2[C8H6(COO)2]2(C5H9NO)2, as determined by thermogravimetry in oxidative atmosphere.

The limited success in the prediction of structure is one of the most serious problems in the engineering of molecular crystals. Here we show that the packing of high-symmetry molecules such as ball-shaped rotating fullerenes, cube-shaped cubane, and octahedral-shaped mesitylene dimers give rise to the formation of cubic cocrystals with easily predictable lattice parameters. We present the synthesis and structure determination of Sc 3 N@C 80 -I h cocrystals with cubane (C 8 H 8 ) and mesitylene (C 9 H 12 ) and compare the new materials with related C 60 -and C 70 -based structures. In this family of materials, most atom-to-atom interactions are averaged out by the symmetry, and the crystal structures can be described in terms of classical molecule-to-molecule interactions. Size-dependent homoand heteromolecular contacts control the stability of the ball-cube and ball-octahedron systems creating several host−guest and recognition-controlled regions. The analysis of the global phase diagrams explains not only the stability of the observed materials, but also the instability of a missing derivative.