Recently recognized as a water contaminant in the United States, perchlorate (ClO4−) has been added to the Environmental Protection Agency's “Contaminant Candidate List” (CCL) and “Unregulated Contaminants Monitoring Rule” (UCMR). Removal of perchlorate from water is difficult because of its high solubility and kinetic inertness. Oxorhenium(V) oxazoline complexes catalyze the reduction of perchlorate to chloride with organic sulfides [Eq. (1)] at exceptionally fast rates with no sign of deactivation. Tf=trifluoromethanesulfonyl, TON=turn‐over number.

The magnetic anisotropy associated with a pentagonal bipyramidal coordination sphere is examined on the basis of experimental and theoretical investigations; effects of crystal field, structural distortion, and second coordination sphere are discussed.