Linkage and Geometrical Isomers of Dichloridobis(triphenylphosphine)ruthenium(II) Complexes with Quinoline‐2‐carbaldehyde (Pyridine‐2‐carbonyl)hydrazone: Their Molecular Structures and Electrochemical and Spectroscopic Properties. Issue 1 (2nd December 2013)

• Record Type: Journal Article
• Authors: Mori, Asami; Suzuki, Takayoshi; Sunatsuki, Yukinari; Kobayashi, Atsushi; Kato, Masako; Kojima, Masaaki; Nakajima, Kiyohiko
• Is Part Of: European journal of inorganic chemistry. Issue 1(2014)
• Page Start: 186
• Page End: 197
• Publication Date: 2013-12-02
• Subjects: Hydrazones -- Isomers -- Isomerization -- Ruthenium -- Solvatochromism; Chemistry, Inorganic -- Periodicals; Organometallic chemistry -- Periodicals; Bioinorganic chemistry -- Periodicals; Solid state chemistry -- Periodicals; 546
• DOI: 10.1002/ejic.201301150
• Languages: English
• ISSNs: 1434-1948

Abstract

Abstract: The reactions of quinoline‐2‐carbaldehyde (pyridine‐2‐carbonyl)hydrazone (HL) and [RuCl2 (PPh3 )3 ] in various solvents at different temperatures gave the three geometrical isomers trans(Cl, Cl) ‐, cis(Cl, Cl), trans(P, N) ‐, and trans(P, P) ‐[RuCl2 (PPh3 )2 {HL‐κ O (amide), κ N (imine)}] (1, 2, and3, respectively) as well as a linkage isomer trans(P, P) ‐[RuCl2 (PPh3 )2 {HL‐κ N (imine), κ N (quin)}] (4 ). The molecular and crystal structures of1 –4, together with both E and Z configurational isomers (with respect to the C=N double bond) of the free ligand HL, were determined by X‐ray analysis. The ligand HL adopted a Z form and acted as a κ O (amide), κ N (imine) bidentate ligand in1 –3, whereas it was an E isomer with a κ N (imine), κ N (quin) coordination mode in4 . The gradual thermal conversions of1 to2 and of2 to3 were observed in dichloromethane and ethanol, respectively, but an interconversion between3 and4 was not detected. In dichloromethane, all complexes have a reversible Ru III/II redox couple in the range 110–412 mV (vs. Ag/Ag + ), and the redox potential was largely dependent on the coordination mode of HL and on the mutual configuration of the two PPh3 ligands. Such a potential shift can be interpreted as a combination of Cl – /amide O π‐donor and PPh3 /quinoline N π‐acceptor orbital contributions to the Ru II dπ orbitals [highest occupied molecular orbitals (HOMOs)]. Complexes3 and4 in acetonitrile showed a gradual spectral change, probably because of the substitution of the Cl – ligand by the acetonitrile solvent. In addition, 2 –4 showed solvatochromic behavior even in noncoordinating solvents that resulted from a blueshift of the metal‐to‐ligand charge‐transfer (MLCT) transition band in polar solvents. These electrochemical and spectroscopic properties are also supported by DFT and time‐dependent DFT (TD‐DFT) calculations. Abstract : A new series of geometrical and linkage isomers of ruthenium(II) complexes with a multidentate hydrazone ligand are prepared. The kinetically formed complex1 gradually converts into the isomer2 in CH2 Cl2, and in EtOH, 2 isomerizes to the thermodynamically most stable isomer3 . The linkage isomer4 is also obtained by using 1, 2‐dichloroethane as the reaction solvent.