Ruthenium complexes supported by 2,6-bis(pyrazol-1-yl)pyridines

Article abstract of DOI:10.1016/S0020-1693(02)01173-8

The synthesis and characterization of a series of ruthenium(II) complexes containing the planar tridentate ligands 2,6-bis(pyrazol-1-yl)pyridine (BPP) or 2,6-bis(3,5-dimethylpyrazol-1-yl)pyridine (Me₄BPP) are described. The reaction of BPP with RuCl₂(PPh₃)₃ yields both the cis (1a) and trans (1b) isomers of [RuCl(PPh₃)₂(BPP)]Cl. Complexes of the general formula trans-RuCl₂(L)(Me₄BPP) (L=PPh₃, 2; C₂H₄, 3a; CO, 3b; MeCN, 3c) are also reported, and were prepared from either RuCl₂(PPh₃)₃ and Me₄BPP (i.e. 2), Et₃N reductions of RuCl₃(Me₄BPP) in the presence of L (i.e. 2 and 3b,c), or from [RuCl₂(p-cymene)]₂, Me₄BPP and L (i.e. 3a). The neutral vinylidene complex cis-RuCl₂(=C=CHPh)(Me₄BPP) (4), was isolated from reactions of phenylacetylene with either 3a or mixtures of [RuCl₂(p-cymene)]₂ and Me₄BPP, while the cationic allenylidene complex [RuCl(PPh₃)(=C=C=CPh₂)(Me₄BPP)][BF ₄] (5), was prepared from 2, AgBF₄ and 1,1-diphenyl-2-propyn-1-ol. Complexes 1-5 were characterized by multinuclear NMR and IR spectroscopy.