Microwave-Assisted Kumada-Type Cross-Coupling Reactions of Iodinated Carba-closo-dodecaborate Anions

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.