Donor-Stabilised [SbF4 ]+ : SbF5 as a Fluoride-Ion Donor

Fluoride-Ion Donor Properties of AsF5

Arsenic pentafluoride undergoes ligand-induced autoionization in the presence of 1,10-phenanthroline (phen) in a SO2ClF solution to form the donor-stabilized [AsF4(phen)][AsF6] salt. Reacting [AsF4(phen)][AsF6] with the strong Lewis acid SbF5·SO2 yields the mixed arsenic-antimony salt [AsF4(phen)][Sb2F11]. These salts are the first examples of crystallographically characterized donor-stabilized [AsF4]+ cations. The analogous reaction of AsF5 and 2,2'-bipyridine (bipy) does not result in autoionization but leads to the formation of the neutral 2:1 adduct (AsF5)2·bipy. The gas-phase and solution fluoride-ion affinities of [AsF4]+ and [SbF4]+ were calculated, revealing them to be incredibly strong Lewis acids. Density functional theory calculations and natural bond orbital analysis show that significant electron-pair donation from phen to the As center in [AsF4(phen)]+ occurs and quenches the extreme electrophilicity of the [AsF4]+ cation.

SO2ClF: A Reagent for Controllable Chlorination and Chlorooxidation of Simple Unprotected Indoles

Sulfuryl chlorofluoride was first employed as a versatile reagent for controllable chlorination and chlorooxidation of simple unprotected indoles. Three types of products including 3-chloro-indoles, 3-chloro-2-oxindoles, and 3,3-dichloro-2-oxindoles could be selectively obtained in good to excellent yields by switching the reaction solvents. The present method features easy-to-operate, broad substrate scope, and mild reaction conditions.

Insights on the Lewis Superacid Al(OTeF5 )3 : Solvent Adducts, Characterization and Properties

Preparation and characterization of the dimeric Lewis superacid [Al(OTeF5 )3 ]2 and various solvent adducts is presented. The latter range from thermally stable adducts to highly reactive, weakly bound species. DFT calculations on the ligand affinity of these Lewis acids were performed in order to rank their remaining Lewis acidity. An experimental proof of the Lewis acidity is provided by the reaction of solvent-adducts of Al(OTeF5 )3 with [PPh4 ][SbF6 ] and OPEt3 , respectively. Furthermore, their reactivity towards chloride and pentafluoroorthotellurate salts as well as (CH3 )3 SiCl and (CH3 )3 SiF is shown. This includes the formation of the dianion [Al(OTeF5 )5 ]2- .