Lewis Electron- Dot Structure of boron fluoride BF molecule - #41 | Chemistry Net

Lewis Electron- Dot Structure of boron fluoride BF molecule - #41

A simple and general method for writing Dot Structures - 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, #26, #27, #28, #29, #30, #31, #32, #33, #34 , #35, #36#37,  #38,  #39 and #40



Let us consider the case of the BF molecule. Boron monofluoride is an unstable gas but forms stable ligands when combines with transition metals1, like the CO molecule. The experimental BF bond length has been found to be 1.263 Angstrom. The bond order for the BF bond has been calculated to be 1.4.2


Step 1: Connect the atoms with single bonds. 

Connct the atom of boron fluoride with single bonds

Fig. 1 : Connect the atoms of the BF molecule with single bonds.
 Step 2:  Calculate the # of electrons in π bonds (multiple bonds) using  formula (1)


Where n in this case is 2 since BF consists of two atoms.
Where V = (3 + 7) = 10 , V is the number of valence electrons of the ion.
Therefore, P = 6n + 2 – V = 6 * 2 + 2 – 10  = 4     So, there are 2 double or 1 triple bond.
Since there are only 2 atoms in the BF molecule there is no possibility that 2 double bonds will be present.    

Step 3 & 4: The  Lewis electron dot resonance structures of  BF   are as follows:
Plausible Lewis Resonance Structures of Boron Fluoride BF

Fig. 2 : Plausible Lewis Resonance Structures of boron fluoride
 
Resonance structure #3 is the most plausible since there is no charge separation. Lewis resonance structure #2 is more possible than #1 since there is less charge separation.

Quantum mechanical and theoretical studies have shown that the bond order in BF is ~1.4 – the bond between the B and the F atom is between a single and a double bond. 




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