B. E. Douglas, D. H. McDaniel, J. J. Alexander, Concepts and Models of Inorganic Chemistry, 3rd edition, John Wiley & Sons, New York, 1994, page 102.
 
 

Problem 2.2

Assign formal charges and oxidation numbers, and evaluate the relative importance of three Lewis structures of OCN-, the cyanate ion. Compare these to the Lewis structures of the fulminate ion, CNO- (encountered in explosive compounds).
 
 

Answer:

cyanate ion:


 
 

fulminate ion


 

The two lowest energy structures are a close call.