[gloinddark]

I have a dilemma on the partial charges found on nitrogen and boron in borazine. Most sources show that the borons have a negative charge and the nitrogens a positive charge; which doesn't make much sense to me, as nitrogen is more electronegative than boron, I suppose.
I saw this 'mistake' also in Housecroft's Inorganic Chemistry. My question is, is it really a mistake, or am I missing something?

Thanks a lot.

[BluePill]

It's not a mistake. You're just missing something. Try drawing a resonance of it. Hint: It looks like benzene. 

[gloinddark]

Thanks for your quick reply!

So the nitrogens do have a positive charge (since they are contributing more electrons), but the pi-electrons can delocalise onto the nitrogen... so that justifies why nucleophilic addition occurs on the boron not the nitrogens. Correct?

I got the resonance structures and info from http://web.tock.com/kalee/chem32/org/17s.html

[BluePill]

Let's iron things out:

1.) Resonance is the reason why nitrogen and boron would appear to have positive and negative charge respectively.
2.) Electrophilic attack is possible because nitrogen has a lone pair that it can use.
3.) Nucleophilic attack on boron can be explained using the octet rule. It can accept a pair of electron from another atom to have a noble gas configuration.

I think the resonance explanation would contradict the nucleophile-electrophile scenario. I think they are mutually exclusive. But then again, I'm willing to be corrected.