Synthesis and crystal structure of supramolecular adducts of macrocyclic cavitand cucurbituril with chromium(III) and nickel(II) aqua complexes

Supramolecular compounds ([Cr(H2O)(6)](C36H36N24O12))(NO3)(3) (.) 13H(2)O (I) and ([Ni(H2O)(6)](2)(C36H36N24O12))(SO4)(2) (.) 16H(2)O (II) were obtained from aqueous solutions of chromium nitrate or nickel sulfate and the macrocyclic cavitand cucurbituril. According to X-ray diffraction analysis data, the cucurbituril molecule is closed from both sides by metal aqua complexes due to the formation of hydrogen bonding between the cucurbituril CO groups and aqua ligands. Compound I has a chain structure, while the structure of compound II is layered. Modes of cucurbituril coordination, depending on the size and charge of the metal cation, are discussed.