A file containing both of these molecules is in the library. To load this file select Load a Molecule from Library on the Build Options dialog and OK.
open the inorganics directory
select the bf3_nh3 file and Open.
You should now have
Reacting BF3 + NH3
A file containing both of these molecules is in the library. To load this file select Load
a Molecule from Library on the Build Options
dialog and OK.
open the inorganics directory
select the bf3_nh3 file and Open.
You should now have
Run Mopac to optimize the structure. Rotate the result it should be clear that the
boron is no longer planar. You can examine the geometry in build mode.
Click 
to start the geometry calculation
function. Click the N and B atoms and the information N B 1.785
Cov.Sum 1.57 should be on the status line. The N-B distance indicates a long bond
since it is 0.2 Angst longer than the sum of the covalent radii (this is normal
for dative or coordinate bonds). The F-B-F
angles are just over 113º
which is a lot less than the 120º
of a planar structure. If you would like to have a bond between the N and B
atoms then use the Mk.CONN command in build mode to add a temporary bond
or connection. These may be removed using the Rm.CONN command.
In build mode use the Rm.CONN command first and then Del.MOL to delete the ammonia
molecule and optimize the BF3 again when it should return to planar
geometry.
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