Synthesis and crystal structure of the complex [Mg(H2O)2(dmf@CB[6])(bdc)]·DMF·4H2O and the inclusion compound [dmf@CB[6]]·8H2O

The complex [Mg(H2O)2(dmf@CB[6])(bdc)]·DMF·4H2O (1) and the inclusion compound [dmf@CB[6]]·8H2O (2) were obtained from a mixture of magnesium perchlorate and water (for compound 1) or magnesium oxide and H2SO4 (for compound 2), and cucurbit[6]uryl (CB[6]) in the presence of N,N-dimethylformamide (DMF) with the additives of terephthalic or fumaric acid, respectively. X-ray diffraction studies showed that magnesium cation in compound 1 coordinated two oxygen atoms of the CB[6] molecule, one oxygen atom of the terephthalate anion, two molecules of water, and a DMF molecule located inside the cucurbit[6]uryl cavity. When fumaric acid was used instead of terephthalic acid under similar conditions of synthesis, no coordination of magnesium cations to cucurbit[6]uryl molecules took place, rather an inclusion compound of DMF into the macrocyclic cavitand was formed. Compounds 1 and 2 were characterized by X-ray diffraction data, IR spectroscopy, and elemental analysis.