New, Highly Efficient Catalyst Precursors for Kharasch Additions − [RuCl(Cp*)(PPh3)2] and [RuCl(Ind)(PPh3)2]

[RuCl(Cp*)(PPh3)2] and [RuCl(Ind)(PPh3)2] are excellent catalyst precursors for promoting the Kharasch addition of CCl4 and CHCl3 across olefins under mild reaction conditions (at temperatures as low as 40 °C with CCl4). The effect of the substituents on the cyclopentadienyl ring has been investigated. In terms of efficiency and activity, [RuCl(Cp*)(PPh3)2] and [RuCl(Ind)(PPh3)2] surpass the best ruthenium systems reported so far. A two-step mechanism, in which the extrusion of a phosphane ligand occurs prior to the activation of the halogenated compound by the unsaturated ruthenium center, is suggested.