Synthesis, Structure and Reactivity of Ruthenium( II ) Carbonyl Complexes Containing Bis(pyrazol‐1‐yl)methane and Bis( N ‐methylimidazol‐2‐yl)methane

A series of ruthenium( II ) complexes with the pyrazolylalkane ligands bis(pyrazol‐1‐yl)methane (BPM) ( I ) and bis(3,5‐dimethylpyrazol‐1‐yl)methane (dmBPM) ( II ), and the imidazolylalkane ligand bis( N ‐methylimidazol‐2‐yl)methane (BIM) ( III ) have been synthesised and characterised. The complexes [Ru(N‐N)(CO) 2 X 2 ] [N‐N = BPM, X = Cl ( 1a ), Br ( 1b ); N‐N = dmBPM, X = Cl ( 2 ); N‐N = BIM, X = Cl ( 3 )] were prepared from the stoichiometric reaction of [Ru(CO) 2 X 2 ] n and the bidentate N‐donor ligand in refluxing methanol. The crystal structure of 2 showed the complex to have octahedral geometry about the ruthenium centre, with the carbonyl and chloride ligands being coordinated cis and trans , respectively. The complex [Ru(BPM) 2 (CO)(Cl)][BPh 4 ] ( 4 ) was prepared from the reaction of RuCl 3 and BPM in refluxing DMF, or from the decarbonylation of [Ru(BPM)(CO) 2 Cl 2 ] ( 1a ) in the presence of BPM and NaBPh 4 . The NMR spectra of 4 were fully assigned from 2D NMR experiments. The NOESY showed a cis coordination of the chloride and carbonyl ligands, and this was confirmed by single crystal X‐ray diffraction studies. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)