HW Problem #81

[TiffanyL1G]

In the 6th Edition of the Chemical Principles book the textbook draws a Lewis Structure that gives Boron a double bond with Nitorgen when it does that doesn't it give Boron a -1 charge? But the initial molecule does not have a charge so shouldn't we just draw a lone pair on each Nitrogen? Does this then change the hybrid orbitals to sp3 instead of sp2?

[AdityaGuru1H]

The formal charge on all 3 of the Boron is -1 but the formal charge on all 3 of the Nitrogen is +1 so when you add up all of the formal charges to get the total charge of the molecule you get zero. As such there is no need for a lone pair on any of the molecules so for both N and B the hybridization is sp2 since the only have 3 regions of electron density.