Dean Jones says:

"That IS the very best offer I'm prepared to make at this time...

Look, perhaps there is nothing I can do that will satisfy your concerns.  Perhaps we had best end this negotiation and each pursue other options.  Regardless, I wish you well with your job search."

Critique:

Obviously you did not reach an agreement.  The Dean probably didn't believe that you actually had another offer in hand.  Or perhaps he felt that you would use his offer to get the other school to raise their bid.

You may wish to try again to see if you can have a more satisfactory outcome.