Frustrated Lewis Pair Modification by 1,1-Carboboration: Disclosure of a Phosphine Oxide Triggered Nitrogen Monoxide Addition to an Intramolecular P/B Frustrated Lewis Pair

摘要

The vicinal frustrated Lewis pair (FLP) mes_2P-CH_2CH_2-B(C_6F_5)_2 reacts with phenyl(trimethylsilyl)-acetylene by 1,1-carboboration to give the extended C_3-bridged FLP 6 featuring a substituted vinylborane subunit. The FLP 6 actively cleaves dihydrogen. The FLP 3 also undergoes a 1,1-carboboration reaction with diphenylphosphino- (trimethylsilyl)acetylene to give the P/B/P FLP 11 that features a central unsaturated four-membered heterocyclic P/B FLP and a pendant CH_2CH_2-Pmes_2 functional group. Compound 11 reacts with nitric oxide (NO) by oxidation of the pendant Pmes_2 unit to the P(O)mes_2 phosphine oxide and N,N-addition of the P/B FLP unit to NO to yield the persistent P/B/PO FLPNO aminoxyl radical 14. This reaction is initiated by P(O)mes_2 formation and opening of the central Ph_2P…B(C_6F_5)_2 linkage triggered by the pendant CH_2CH_2-P(O)mes_2 group.