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Isolable Silicon-Based Polycations with Lewis Superacidity.

ABSTRACT: Molecular silicon polycations of the types R₂ Si²⁺ and RSi³⁺ (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 R₂ Si²⁺ and RSi³⁺ complexes, [R₂ Si(terpy)]²⁺ (R=Ph 1²⁺ ; R₂ =C₁₂ H₈ 2²⁺ , (CH₂ )₃ 3²⁺ ) and [RSi(terpy)]³⁺ (R=Ph 4³⁺ , cyclohexyl 5³⁺ , m-xylyl 6³⁺ ), 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(sp³ )-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.

SUBMITTER: Hermannsdorfer A

PROVIDER: S-EPMC7756528 | biostudies-literature | 2020 Dec

REPOSITORIES: biostudies-literature

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Isolable Silicon-Based Polycations with Lewis Superacidity.

Hermannsdorfer André A Driess Matthias M

Angewandte Chemie (International ed. in English) 20201015 51

Molecular silicon polycations of the types R2 Si2+ and RSi3+ (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 R2 Si2+ and RSi3+ complexes, [R2 Si(terpy)]2+ (R=Ph 12+ ; R2 =C12 H8 22+ , (CH2 )3 32+ ) ...[more]

PMID: 32935903

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