Reactivity of cyano- and isothiocyanatoborylenes: metal coordination, one-electron oxidation and boron-centred Bronsted basicity.

ABSTRACT: Doubly base-stabilised cyano- and isothiocyanatoborylenes of the form LL'BY (L = CAAC = cyclic alkyl(amino)carbene; L' = NHC = N-heterocyclic carbene; Y = CN, NCS) coordinate to group 6 carbonyl complexes via the terminal donor of the pseudohalide substituent and undergo facile and fully reversible one-electron oxidation to the corresponding boryl radical cations [LL'BY]˙⁺. Furthermore, calculations show that the borylenes have very similar proton affinities, both to each other and to NHC superbases. However, while the protonation of LL'B(CN) with PhSH yielding [LL'BH(CN)⁺][PhS^-] is fully reversible, that of LL'B(NCS) is rendered irreversible by a subsequent B-to-C_CAAC hydrogen shift and nucleophilic attack of PhS^- at boron.

SUBMITTER: Hagspiel S 

PROVIDER: S-EPMC8188585 | biostudies-literature | 2021 May

REPOSITORIES: biostudies-literature