Air-stable aryl derivatives of pentafluoroorthotellurate

Abstract

We report on two different sets of air-stable derivatives of the pentafluoroothotellurate containing fluorinated and non-fluorinated aryl groups. The acid cis-PhTeF4OH was obtained in gram scale and further transformed to...

A Highly Sterically Encumbered Boron Lewis Acid Enabled by an Organotellurium‐Based Ligand

“…In the solid state, there is a negligible interaction between the ions, and the anion shows a slightly distorted octahedral geometry at the Te centre (Figure 1). This is in contrast to the previously reported K[OTeF 3 (C 6 F 5 ) 2 ] ⋅ MeCN, in which the cation‐anion interaction is considerably stronger [17] …”

“…This is in contrast to the previously reported K[OTeF 3 (C 6 F 5 ) 2 ] • MeCN, in which the cationanion interaction is considerably stronger. [17] With this reactivity in hand, we explored the possibility of transferring the OTeF 3 (C 6 F 5 ) 2 ligand to a boron centre in a similar fashion in order to prepare a Lewis acid. In fact, the reaction of BCl 3 with three equivalents of 1 in dichloromethane at À 78 °C yields the Lewis acid B[OTeF 3 (C 6 F 5 ) 2 ] 3 (3) quantitatively under formation of three equivalents of HCl (Figure 2a).…”

“…The recently reported synthesis of the acid HOTeF 3 (C 6 F 5 ) 2 ( 1 ) requires the use of anhydrous HF in the final protonation step of the protocol, [17] which made us seek for a more convenient alternative. Gratifyingly, when the starting material trans ‐(C 6 F 5 ) 2 TeF 4 is stirred overnight at room temperature in an acetonitrile/water mixture (15 % v/v H 2 O in MeCN), a selective hydrolysis of one Te−F bond can be achieved and HOTeF 3 (C 6 F 5 ) 2 ( 1 ) can be isolated in very good yield (86 %).…”

“…[16] We have recently designed and synthesized teflate derivatives containing aryl groups, namely [cis-PhTeF 4 O] À and [trans-(C 6 F 5 ) 2 TeF 3 O] À (from now on simplified as À OTeF 3 (C 6 F 5 ) 2 ). [17] These groups are stable to moisture and air, contrary to the teflate ligand, and might additionally provide a huge steric shielding to the acidic centre to which they are bonded due to the presence of the aryl groups. The outstanding properties of the pentafluorophenyl derivative, which comprise a higher Brønsted acidity and robustness against fluoride abstraction compared to the phenyl analogue, prompted us to employ it for the synthesis of Lewis acids.…”

“…We have recently designed and synthesized teflate derivatives containing aryl groups, namely [ cis ‐PhTeF 4 O] − and [ trans ‐(C 6 F 5 ) 2 TeF 3 O] − (from now on simplified as −OTeF 3 (C 6 F 5 ) 2 ) [17] . These groups are stable to moisture and air, contrary to the teflate ligand, and might additionally provide a huge steric shielding to the acidic centre to which they are bonded due to the presence of the aryl groups.…”