Flash Communication: Properties and Applications of a Pentavalent Bromoantimony Lewis Acid

High Resolution Image Download MS PowerPoint Slide While normally reluctant toward oxidation, SbBr 3 can be oxidized with 3,4,5,6-tetrachloro-1,2-benzoquinone ( o -chloranil) in the presence of a Lewis base like the bromide anion or triphenylphosphine oxide (PPh 3 O) to form the tetrachlorocatecholate (cat Cl ) derivatives [SbBr 4 (cat Cl )] − ([ 2 -Br] − ) and SbBr 3 (cat Cl )•OPPh 3 ( 2 •OPPh 3 ), respectively. Structural, spectroscopic, and computational data indicate that the SbBr 3 (cat Cl ) fragment is similarly, if slightly less, Lewis acidic than the previously reported SbCl 3 (cat Cl ) fragment. The SbBr 3 / o -chloranil system, as well as its previously reported counterpart SbCl 3 / o -chloranil, were tested as Lewis acid catalysts for C–O bond metathesis and polycarbonate depolymerization. These results identified SbX 3 / o -chloranil pairs (X = Cl, Br) as simple main-group platforms for C–O bond cleavage chemistry.