The microwave-assisted Pd-catalyzed Kumada-type cross-coupling reaction of iodinated carba-closo-dodecaborate anions requires smaller amounts of Grignard reagent and catalyst and results in higher yields in much shorter reaction times in comparison to a reaction with conventional heat transfer. 12-Ph3P-closo-1-CB11H11 was identified as the side product of the cross-coupling reactions that use [PdCl2(PPh3)(2)]. The inner salt, which is the first example for a {closo-1-CB11} cluster with a B-P bond, was selectively synthesized via a related microwave-assisted cross-coupling protocol and characterized by NMR spectroscopy, elemental analysis, and single-crystal X-ray diffraction. In addition, the crystal structures of the tetraethyl ammonium salts of [12-Ph-closo-1-CB11H11](-), [12-(4-MeOC6H4)-closo-1-CB11H11](-), and [12-(H2C=(Me)CC C)-closo-1-CB11H11](-) are described.