Indirect synthesis of a pair of formal methane activation products at a phosphane/borane frustrated Lewis pair

Abstract

The regioisomeric formal Mes2PCH2CH2B(C6F5)2 FLP methane splitting products Mes2P(H)CH2CH2B(CH3)(C6F5)2 and Mes2P(CH3)CH2CH2B(H)(C6F5)2 were produced by indirect stepwise reactions. They were stable at 60 °C and were both characterized by X-ray diffraction. A DFT analysis revealed that their formation from the FLP and CH4 would be endergonic by +6.9 and +3.6 kcal mol−1, respectively, and it indicated that methane elimination from the zwitterionic products is kinetically hindered by barriers of 54.0 and 72.3 kcal mol−1, respectively.