Abstract The rigid cyclic Lewis acids [(C 6 F 5) B (CH 2)(C 6 F 4) P (tBu) 2]+([1]+),[(C 6 F 5) B (CH 2)(C 6 F 3 H) P (tBu) 2]+([2]+), and [(C 6 H 5) B (CH 2)(C 6 F 4) P (tBu) 2]+([3]+), possess Gutmann acceptor numbers of AN= 87.3, 85.7, and 85.7, respectively, which are among the highest for organoboranes. Starting from (1) OTf, adducts [(1) Do][OTf](Do= OPEt 3, pyridine, H 2 O) have been prepared and fully characterized. In all three cases, X-ray ...
