When this polyatomic ligand is bonded to a trimethylsilyl group, but not a similar tert-butyl group, it rapidly interconverts which of its atoms is bonded to the group. A compound of cobalt(II) and this ligand is a cubic lattice with another cobalt atom inside half of the cubes, giving a zeolite-like structure. Compounds of transition metals with this ligand form the widest variety of, and best studied, coordination (*) polymers, as this ligand is the simplest to have two atoms that both readily bond to metal centers. The most common method of gold refining forms a complex of gold (10[1])with this ligand that is water-soluble. (-5[1])Iron(II) complexed to six instances of this ligand is a component of Prussian blue. (10[1])For 10 points, name this toxic anion made of a triple-bonded carbon and nitrogen. ■END■ (10[1])