Chlorination of Boron on a Ruthenium-Coordinated Hydridotris(pyrazolyl)borate (Tp) Ligand: A Caveat for the Use of TpRu(PPh3)2Cl

A side-product that accompanies the synthesis of the widely utilized starting material TpRu(PPh3)(2)Cl (Tp = hydridotris(pyrazolyl)borate) has been identified as the complex (Cl)TpRu(PPh3)(2)H ((Cl)Tp = chlorotris(pyrazolyl)borate), which provides a rare example (if a boron-halogenated pyrazolylborate ligand. The reaction of (Cl)TpRu(PPh3)(2)H with dichloromethane or chloroform quantitatively produce (Cl)TpRu(PPh3)(2)Cl.