| Title
| - Synthesis, Structure, and Spectroscopic, Photochemical, Redox, andCatalytic Properties of Ruthenium(II) Isomeric Complexes ContainingDimethyl Sulfoxide, Chloro, and the Dinucleating Bis(2-pyridyl)pyrazoleLigands
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| Abstract
| - New isomeric mononuclear Ru(II) complexes containing the dinucleating Hbpp ligand and the dmso and chloro ligands of general formula [RuCl2(Hbpp)(dmso)2] have been prepared and their chemical and physical properties thoroughly investigated. The structures of those complexes have been characterized in the solid state by X-ray diffraction analysis and in solution through 1D and 2D NMR spectroscopy. Those two isomeric complexes display distinctive electrochemical properties with regard to their capacity to undergo linkage isomerization reactions. Finally, those two isomers also show a markedly different activity with regard to their ability to catalyze hydrogen-transfer reactions.
- Two isomeric Ru(II) complexes containing the dinucleating Hbpp (3,5-bis(2-pyridyl)pyrazole) ligand together with Cland dmso ligands have been prepared and their structural, spectroscopic, electrochemical, photochemical, andcatalytic properties studied. The crystal structures of trans,cis-[RuIICl2(Hbpp)(dmso)2], 2a, and cis(out),cis-[RuIICl2(Hbpp)(dmso)2], 2b, have been solved by means of single-crystal X-ray diffraction analysis showing a distortedoctahedral geometry for the metal center where the dmso ligands coordinate through their S atom. 1D and 2DNMR spectroscopy corroborates a similar structure in solution for both isomers. Exposure of either 2a or 2b inacetonitrile solution under UV light produces a substitution of one dmso ligand by a solvent molecule generatingthe same product namely, cis(out)-[RuIICl2(Hbpp)(MeCN)(dmso)], 4. While the 1 e- oxidation of 2b or cis(out),cis-[RuIICl2(bpp)(dmso)2]+, 3b, generates a stable product, the same process for 2a or trans,cis-[RuIICl2(bpp)(dmso)2]+,3a, produces the interesting linkage isomerization phenomenon where the dmso ligand switches its bond fromRu−S to Ru−O (KIIIO→S = 0.25 ± 0.025, kIIIO→S = 0.017 s-1, and kIIIS→O = 0.065 s-1; KIIO→S = 6.45 × 109, kIIO→S= 0.132 s-1, kIIS→O = 2.1 × 10-11 s-1). Finally complex 3a presents a relatively high activity as hydrogen transfercatalyst, with regard to its ability to transform acetophenone into 2-phenylethyl alcohol using 2-propanol as thesource of hydrogen atoms.
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