Synthesis and Characterization of the Silylated Hexaphenyl Carbodiphosphorane [Me3SiC(PPh3)2][CF3SO3

Abstract

The addition of trimethylsilyl trifluoromethanesulfonate TMS-OTf (CF3SO3 = OTf, triflate) to hexaphenyl carbodiphosphorane PPh3=C=PPh3 (1) in toluene yields the silylated carbodiphosphorane [Me3SiC(PPh3)2][OTf] (2). Compound 2 represents the first silylated carbodiphosphorane characterized in solution and in the solid state. 2 is an air-sensitive compound but stable in solution and in the solid state in an inert atmosphere as shown by heteronuclear NMR experiments and also by X-ray diffraction analysis. Compound 2 crystallizes in the monoclinic space group P21/n with the cell dimensions a = 1161.7(1), b = 1714.4(1), c = 1903.3(1) pm; β = 102.74(1)° and Z = 4. Structure, frontier orbitals, and dissociation energies for 2 were determined by density functional theory-based computations highlighting the character of 2 as a Lewis acid adduct of a carbon(0) compound.