This compound was reacted with buckminster·fullerene to produce the first crystal structure of a buckyball. To dispose of extremely hazardous two-percent solutions of this compound, SDSs recommend neutralizing it with twice the volume of corn oil until it stops turning black. Aqueous sulfurous acid knocks this catalyst off a five-membered ring in a syn addition in which it is regenerated by a sacrificial oxide of morpholine. This inorganic reagent is supplied to reactions by AD-mix. An imidazole (“ih-MID-ah-zahl”) buffer of this compound acts as both a negative lipid stain [emphasize] and a fixative in transmission electron microscopy. This compound would convert propylene (“PRO-pill-een”) into syn-propylene glycol. Barry Sharpless won his first Nobel Prize for an a·symmetric di·hydroxylation catalyzed by the +8 (“plus eight”) oxidation state of this compound’s metal. For 10 points, name this square planar compound that contains the densest element. ■END■ (10[1])