Ruthenium tris(pyrazolyl)borate complexes .1. Synthesis and reactivity of Ru(HB(pz)(3))(COD)X (X=Cl, Br) and Ru(HB(pz)(3))(L(2))Cl (L=nitrogen and phosphorus donor ligands)

The synthesis and catalytic reactivity of a variety of new ruthenium complexes of the tris(pyrazolyl)borate ligand (HB(pz)(3)) are reported in this paper. From the parent-complex Ru(HB(pz)(3))(COD)X (X = Cl, Br) the cationic derivatives [Ru(HB(pz)(3))(COD)L](+) (L = H2O, CH3CN, pyridine, dmso) have been obtained by treatment with 1 equiv of AgCF3SO3 in CH2Cl2 solutions of L. Displacement of COD from these latter complexes has been accomplished in boiling dmf solutions of ligands L(2) = Ph(2)PCH(2)PPh(2) (dppm), Ph(2)PCH(2)CH(2)NMe(2) (pn), and Me(2)NCH(2)CH(2)NMe(2) (tmeda) as well as L = pyridine and 3-methylpyridine to give Ru(HB(pz)(3))(L(2))Cl and Ru(HB(pz)(3))(L)(2)Cl, respectively, each in high yield. From some of these complexes, in turn, the chloride ion has been abstracted with either AgCF3SO3, TICF3SO3, or NaBPh(4) in CH3CN as the solvent. In this way we obtained [Ru(HB(pz)(3))(dppm)(CH3CN)]CF3SO3, [Ru(HB(pz)(3))(pn)(CH3CN)]BPh(4), and [Ru(HB(pz)(3))(tmeda)(CH3CN)]BPh(4). Selected X-ray structures are included. Some of the complexes synthesized are efficient catalysts for the formation of selectively C-O-coupled products from the reaction of phenylacetylene with either benzoic acid or allyl alcohols.