NEW MACROCYCLIC LIGANDS .4. DIBENZO-SUBSTITUTED RINGS INCORPORATING 5DONOR ATOMS - X-RAY STRUCTURES OF AN N4O-DONOR MACROCYCLE, ITS PROTONATED FORM, AND ITS COMPLEX WITH BARIUM PERCHLORATE

The syntheses and characterization of four dibenzo-substituted macrocy cles incorporating N5-, N4O- or N4S-donor sets are reported. The new s ystems extend the range of related (potentially pentadentate) macrocyc lic systems of this general structure reported previously. For the 17- membered macrocycle incorporating an N4O-donor set, X-ray structure de terminations of the free ligand and its salt of type [LH]ClO4 confirm the structure of this compound predicted from physical measurements. T he diperchloratobarium complex of this macrocycle is shown to have the barium nine-coordinate; the coordination sphere is composed of the N4 O-donors of the macrocycle and four oxygen atoms derived from a monode ntate as well as a bidentate perchlorate group and an ethanol molecule .