The charges in the structural formula of BF3 + NH3 on Wikipedia < http://commons.wikimedia.org/wiki/File:NH3-BF3-adduct-bond-lengthening-2D.png > look strange to me. I've asked on the discussion page there < http://commons.wikimedia.org/wiki/File_talk:NH3-BF3-adduct-bond-lengthening-2D.png > if it is correct. I think the charges should be written as ⊕ and ⊖ because they are formal charges, but I am not sure. So far I did not get a reply.
Could you please comment on that? What would be the best way to draw that structural formula? What is the actual charge on boron and nitrogen?
Thank you!