Carbon–carbon activation by rhodium in solution; sp 2 –sp 3 is preferred over sp 3 –sp 3 bond cleavage

Reaction of the ethyl-aromatic phosphine 1 with PhRh(PPh3)3 results in C–H activation, yielding complex 2, which upon treatment with H2 undergoes selective cleavage of the sp2–sp3 hybridized C–C bond forming ethane and complex 3; Ar–C cleavage is also observed upon reaction of 1 with H2 and [RhCl(C8H14)2]2.