Carba-closo-dodecaborates with one or two alkynyl substituents bonded to boron

Salts of the carba-closo-dodecaborate anion with one or two phenyl- or trimethylsilylalkynyl substituents were synthesized by Pd-catalyzed Kumada-type cross-coupling reactions of the corresponding iodinated clusters with alkynyl Grignard reagents. Selective monofunctionalization in the 7- and 12-position of the {closo-CB(11)} cluster was achieved, resulting in salts of the anions: 1-R-12-R'Ctriple bond]C-closo-CB(11)H(10)](-) (R = H, Ph; R' = Ph, Me(3)Si (1-4)), 12-Hal-7-PhCtriple bond]C-closo-CB(11)H(10)](-) (Hal = F (5), Cl (6), Br (7)), and 12-F-7-Me(3)SiCtriple bond]C-closo-CB(11)H(10)](-) (8). Furthermore, the disubstituted derivatives 7,12-(RCtriple bond]C)(2)-closo-CB(11)H(10)](-) (R = Ph (9), Me(3)Si (10)) are described. All salts were characterized by multi-NMR, IR, and Raman spectroscopy as well as by mass spectrometry (MALDI). The crystal structures of Cs(+)1 and Et(4)N](+)6 were determined by single-crystal X-ray diffraction. The spectroscopic and structural properties are compared to values derived from DFT calculations and to data of related boron species with alkynyl groups.