Chlorination of Boron on a Ruthenium-Coordinated Hydridotris(pyrazolyl)borate (Tp) Ligand: A Caveat for the Use of TpRu(PPh 3 ) 2 Cl

A side-product that accompanies the synthesis of the widely utilized starting material TpRu(PPh 3) 2Cl (Tp = hydridotris(pyrazolyl)borate) has been identified as the complex clTpRu(PPh 3) 2H ( clTp - chlorotris(pyrazolyl)bo-rate), which provides a rare example of a boron-halogenated pyrazolylborate ligand. The reaction of clTpRu(PPh 3) 2H with dichloromethane or chloroform quantitatively produce clTpRu(PPh 3) 2Cl