Isolable Silicon-Based Polycations with Lewis Superacidity.

Isolable Silicon-Based Polycations with Lewis Superacidity.
Angew Chem Int Ed Engl. 2020 Sep 16;:
Authors: Driess M, Hermannsdorfer A
Abstract
Molecular silicon polycations of the types R 2 Si 2+ and RSi 3+ (R = H, organic groups) are elusive Lewis superacids and currently unknown in the condensed phase. Here, we report the synthesis of a series of isolable terpyridine-stabilized R 2 Si 2+ and RSi 3+ complexes, [R 2 Si(terpy)] 2+ (R = Ph 1 2+ ; R 2 = C 12 H 8 2 2+ , (CH 2 ) 3 3 2+ ) and [RSi(terpy)] 3+ (R = Ph 4 3+ , cyclohexyl 5 3+ , m-xylyl 6 3+ ), in form of their triflate salts. The stabilization of the latter is achieved through higher coordination and to the expense of reduced fluoride ion affinities, but a significant level of Lewis superacidity is nonetheless retained as verified by theory and experiment. The complexes activate C(sp 3 )-F bonds, as showcased by stoichiometric fluoride abstraction from 1-fluoroadamantane (AdF) and the catalytic hydrodefluorination of AdF. The formation of the crystalline adducts [ 2 (F)] + and [ 5 (H)] 2+ documents in particular the high reactivity towards fluoride and hydride donors .
PMID: 32935903 [PubMed - as supplied by publisher]

Source: Angewandte Chemie - September 15, 2020 Category: Chemistry Authors: Driess M, Hermannsdorfer A Tags: Angew Chem Int Ed Engl Source Type: research