The Heptacyanotungstate(IV) Anion: A New 5 d Transition-Metal Member of the Rare Heptacyanometallate Family of Anions.

The heptacyanotungstate(IV) anion was isolated in the salt (n-Bu4 N)3 [W(IV) (CN)7 ] (1) from the reduction of (n-Bu4 N)3 [W(V) (CN)8 ] with concomitant loss of one cyanide ligand. The anion in 1 adopts a slightly distorted pentagonal bipyramidal geometry with an average W-C distance of 2.169 Å. The spectroscopic and magnetic properties are described.