Canonical Structures|Lewis Dot Structure of OCN-

Canonical Lewis Structures of OCN^-

A simple procedure for writing canonical Lewis Structures was given in a previous post entitled “Lewis Structures and the Octet Rule”. Several worked examples relevant to this procedure were given in previous posts please see the Sitemap - Table of Contents (Lewis Electron Dot Structures).

Let us consider the case of the cyanate ion OCN^- . The cyanate ion is an ambidentate and a bridging ligand. The Lewis structures of the cyanate ion are drawn in 4 steps using the above method.

Step 1: Connect the atoms with single bonds.

 

Step 2: Calculate the # of electrons in pi bonds (multiple bonds) using formula (1):

Where n in this case is 3. Where V = (6 + 4 + 5) – (-1) = 16 , V is the number of valence electrons of the molecule.

Therefore, P = 6n + 2 – V = 6 * 3 + 2 – 16 = 4 So, there are : 2 double bonds or a triple bond.

Step 3 & 4: The resonance structures of OCN^- are as follows:

 

Structures #1 and #3 are more stable due to less charge separation comparing to #2. Structure #3 is more plausible than #1 since the more electronegative O atom has the negative charge. Therefore stability decreases: #3 > #1 > #2

The most plausible Lewis structure is #3 and the least plausible #2.

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Relevant Posts

Lewis Structures|Octet Rule: A Simple Method to write Lewis Structures

Lewis Dot Structure of thiocyanate (SCN-)

Lewis Structures - How to draw Lewis Structure - NCN^-2

 

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References

1. G.N. Lewis, J.A.C.S, 38, 762-785, (1916)
2. E. C. McGoran, J. Chem. Educ., 68, 19-23 (1991)
3. A.B.P. Lever, J. Chem. Educ., 49, 819-821, (1972)

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Key Terms

resonance structures of cyanate ion OCN-, Lewis electron structures of cyanate ion, chemical formula of cyanate ion, simple procedure for drawing Lewis structures of cyanate ion,

 

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