The Thioether-Methyleneborane (PhSCH2B(C6F5)2)2: Synthesis and Reactivity with Donors and Alkynes

2-Bromothioanisole, or thioanisole, was lithiated and subsequently reacted with ClB(C6F5)(2) to yield a new compound with the empirical formulation PhSCH2B(C6F5)(2), 1. NMR data at low temperature as well as X-ray crystallographic data confirmed this species to be the dimer (PhSCH2B(C6F5)(2))(2), although an equilibrium governs the interconversion of monomer to dimer at room temperature. Compound 1 reacts with PtBu3 or OPEt3 to form adducts PhSCH2B(C6F5)(2)(L) (L = PtBu3 2, OPEt3 3) in 85% and 87% yield, respectively. Compound 1 also reacts with alkynes, namely, PhCCH, C4H9CCH, PhCCC4H9, C2H5CCC2H5, and PhCCPh, to give the species (PhSCH2B(C6F5)(2))(R'C=CR) (R = H, R' = Ph 4, C4H9 5, R = Ph, R' = C4H9 6, R = R' = C2H5 7, Ph 8) in yields in the range 70-92%. X-ray crystallographic analysis of 8 confirmed the five-membered zwitterionic heterocyclic formulation.