Simple Procedure for writing Lewis Structures for nitromethane CH3NO2 -#27

A simple procedure for writing Lewis structures is given in a previous article entitled “Lewis Structures and the Octet Rule”. Relevant worked examples were given in the following articles: Examples #1, #2, #3 , #4, #5, #6,  #7,  #8, #9, #10, #11, #12, #13, #14,  #15, #16, #17, #18, #19, #20, #21, #22,  #23,  #24, #25 and #26.

Let us consider the case of nitromethane CH₃NO₂

Nitromethane is the simplest organic nitro compound. It is used as a polar solvent in a variety of industrial applications such as extractions, as a reaction medium and as a cleaning solvent. Nitromethane is an efficient nitrogen donor which makes it a highly functional molecule for organic synthesis for the development and manufacture of products such as pharmaceuticals and agricultural chemicals. Nitromethane is used also as a racing fuel.

Step 1: Connect the atoms with single bonds. 

Fig. 1: Connect the atoms of nitromethane with single bonds

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

Where n in this case is 4 since  CH₃NO₂ consists of seven atoms but three of them are H atoms.

Where V = (1 + 1 +1 + 4 + 5 + 6 + 6 )  = 24  

Therefore, P = 6n + 2 – V = 6 *4 + 2 – 24 = 2    Therefore, there is one double bond.  The structure in Step 1  has one double bond.

Step 3 & 4: The Lewis structure for CH₃NO₂ is as follows:

Fig. 2: Two plausible resonance structures for nitromethane

Therefore, two Lewis electron dot resonance structures were derived for nitromethane using the above method.