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

Abstract

AbstractA 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)2X2] [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)2X2]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)][BPh4] (4) was prepared from the reaction of RuCl3 and BPM in refluxing DMF, or from the decarbonylation of [Ru(BPM)(CO)2Cl2] (1a) in the presence of BPM and NaBPh4. 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)