Synthesis, Properties and Molecular Structure of [Ru(tpm)(bpy)(CH3CN)](PF6)2 (tpm= tris(1-pyrazolyl)methane, bpy= 2,2?-bipyridine). Another example of Nitrile Hydrolysis Catalyzed by Ruthenium(II)

KATZ, NÉSTOR E.; FAGALDE, FLORENCIA; LIS DE KATZ, NOEMÍ D.; MELLACE, MARÍA G.; ROMERO, ISABEL; LLOBET, ANTONI; BENET-BUCHHOLZ, JORDI

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY

Wiley

Lugar: Alemania; Año: 2005 vol. 15 p. 3019 - 3023

1434-1948

Abstract The synthesis and isolation of [Ru(tpm)(bpy)(CH3CN)](PF6)2 (tpm = tris(1-pyrazolyl)methane; bpy = 2,2´-bipyridine) in good yield, is described. This new Ru(II) complex has been spectroscopically (IR, UV-Vis, Emission) and electrochemically (cyclic voltammetry) characterized. Its solid state structure has been solved by means of X-ray diffraction analysis showing a distorted octahedral geometry where as expected the tpm ligand acts in a facial mode, the bpy in a chelate manner and finally the CH3CN ligand saturates the coordination sphere of the Ru metal center. Electrochemical and spectroscopic results indicate that the CH3CN ligand acts as a moderately strong p-acceptor. The capacity of the coordinated CH3CN ligand to undergo basic hydrolysis is also described. A second-order rate constant kobs = 1.3 x 10-3 M-1s-1 (T = 25°C) has been obtained following the UV-Vis absorption changes over time; the activation parameters obtained over the temperature range 17.0-40.0 oC are: DH# = (74 ± 4) kJ/mol and DS# = (-54 ± 12) J/mol K. These results are compared and discussed with regard to related complexes described in the literature that are also capable of carrying out this reaction. The results presented here allow to further characterize and understand how the electronic and steric factors influence the basic hydrolysis of the coordinated CH3CN ligand.