Molecular and crystal structure of 4',5'-dibromobenzo-15-crown-5

The crystal structure of 4',5'-dibromo-B15C5 was studied by X-ray diffraction. The crystallographic parameters of the single crystal are a=16.687(3), b=8.145(2), and c=23.623(4) A; V=2235.0 A3; ρcalc=1.68 g/cm3; Z=8; sp. gr. Pbca. The structure was solved by the direct method and refined by the least-squares procedure to R=0.094. The conformation of the macrocycle in 4',5'-dibromo-B15C5 is characterized by the following sequence of torsion angles: a-a-g-a-g-g-a-a-g(bar sign)-g(bar sign)-a-g-a-a-s. Specific Br···Br interactions observed in the structure connect the 4',5'-dibromo-B15C5 molecules into layers parallel to the xy plane