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Synthesis, Properties and Molecular Structure of [Ru(tpm)(bpy)(CH 3 CN)](PF 6 ) 2 (tpm = tris(1‐pyrazolyl)methane, bpy = 2,2'‐bipyridine) — Another Example of Nitrile Hydrolysis Promoted by Ruthenium( II )
Author(s) -
Katz Néstor E.,
Fagalde Florencia,
Lis de Katz Noemí D.,
Mellace María G.,
Romero Isabel,
Llobet Antoni,
BenetBuchholz Jordi
Publication year - 2005
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.200500160
Subject(s) - chemistry , ligand (biochemistry) , steric effects , bipyridine , ruthenium , crystallography , cyclic voltammetry , reaction rate constant , coordination sphere , 2,2' bipyridine , electrochemistry , stereochemistry , crystal structure , kinetics , catalysis , organic chemistry , biochemistry , receptor , physics , electrode , quantum mechanics
The synthesis and isolation of [Ru(tpm)(bpy)(CH 3 CN)](PF 6 ) 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 and shows a distorted octahedral geometry where, as expected, the tpm ligand occupies three facial coordination sites, the bpy ligand chelates two further sites, and the CH 3 CN ligand saturates the coordination sphere of the Ru metal center. Electrochemical and spectroscopic results indicate that the CH 3 CN ligand acts as a moderately strong π‐acceptor. The capacity of the coordinated CH 3 CN ligand to undergo basic hydrolysis is also described. A second‐order rate constant k obs = 1.3 × 10 –3 M –1 s –1 ( T = 25 °C) has been obtained by following the UV/Vis absorption changes over time; the activation parameters obtained over the temperature range 17.0–40.0 °C are: Δ H ‡ = 74 ± 4 kJ mol –1 and Δ S ‡ =–54 ± 12 J mol –1 K –1 . 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 make it possible to characterize the electronic and steric factors further and understand how they influence the basic hydrolysis of the coordinated CH 3 CN ligand. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)