RUTHENIUM TRIS(PYRAZOLYL)BORATE COMPLEXES - FORMATION AND CHARACTERIZATION OF ACETONE, DIMETHYLFORMAMIDE AND VINYLIDENE COMPLEXES CONTAINING N,N-DONOR CO-LIGANDS

Chloride abstraction from [Ru{HB(pz)(3)}(tmen)Cl] (pz = pyrazolyl, tme n = Me(2)NCH(2)CH(2)NMe(2)) with NaBPh(4) 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 phenylacetyle ne, these are easily transformed into the first example of a ruthenium HB(pz)(3) vinylidene complex. Extended-Huckel molecular-orbital calcu lations have been performed to establish the nature of the bonding inv olved. From [Ru{HB(pz)(3)}(py)(2)Cl] (py = pyridine) the corresponding vinylidene complex could be prepared in the same way, although the in termediate solvent complexes could not be isolated. Selected crystal s tructures were determined.