Ruthenium tris(pyrazolyl)borate complexes. Formation and characterization of acetone, dimethylformamide and vinylidene complexes containing N,N-donor co-ligands

Abstract

Chloride abstraction from [Ru{HB(pz)₃}(tmen)Cl](pz = pyrazolyl, tmen = Me₂NCH₂CH₂NMe₂) with NaBPh₄ in the solvents acetone and dimethylformamide led to the formation of the respective cationic [Ru{HB(pz)₃}(tmen)(solv)]⁺ complexes. In the presence of phenylacetylene, these are easily transformed into the first example of a ruthenium HB(pz)₃ vinylidene complex. Extended-Hückel molecular-orbital calculations have been performed to establish the nature of the bonding involved. From [Ru{HB(pz)₃}(py)₂Cl](py = pyridine) the corresponding vinylidene complex could be prepared in the same way, although the intermediate solvent complexes could not be isolated. Selected crystal structures were determined.