Both buyer and seller knew that there could be no deal under their terms until the stockholders voted.
WB might be vulnerable to some smaller damages if they violated some valid agreements, such as maybe an agreement that WB would not use the Citi offer to shop for other offers....
But I doubt they can force their deal to go through.
The stockholders will kill that in the manner I described.
Link to the Wachovia/Citigroup exclusivity agreement.
http://media.charlotteobserver.com/smedia/2008/10/03/12/citipact.source.prod_affiliate.138.pdf