10.1002/anie.201209107
The research focuses on the synthesis and application of perhalogenated carba-closo-dodecaborate anions as ligand substituents in gold catalysis. The study explores the use of HCB11Cl11? anion (1) as a super-bulky, inert, and charged ligand substituent due to its large van der Waals volume and weakly coordinating properties. The researchers synthesized a phosphine ligand, iPr2P(CB11Cl11)Li? (2), and demonstrated its utility by preparing unique single-component AuI catalysts with unprecedented activity for the hydroamination of alkynes with primary amines. The experiments involved the treatment of the trimethylammonium salt of anion 1 with nBuLi and subsequent quenching with iPr2PCl to afford 2, which was then combined with chloro(tetrahydrothiophene)gold(I) to form the zwitterionic Au complex 3(THT). The catalytic properties of 3 were evaluated in the hydroamination of primary amines with alkynes, showing high activity even at ultra-low catalyst loadings, with the highest reported TON reaching 92000. The study utilized techniques such as 1H and 31P NMR spectroscopy to monitor reactions and X-ray diffraction to confirm the structures of the synthesized compounds.