[Ru(PPh3)3Cl2]-Mediated Transformation of –CH3 into =CHPHPh3 in Biacetylmonoxime Acetyl-/Aroylhydrazones: Ruthenium(III) Complexes with the Transformed Ligands
✍ Scribed by Raji Raveendran; Samudranil Pal
- Publisher
- John Wiley and Sons
- Year
- 2008
- Tongue
- English
- Weight
- 253 KB
- Volume
- 2008
- Category
- Article
- ISSN
- 1434-1948
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✦ Synopsis
Abstract
Ruthenium(III) complexes of general formula trans‐[Ru(^t^L)(PPh~3~)Cl~2~] have been isolated in 58–73 % yields from reactions between [Ru(PPh~3~)~3~Cl~2~] and tridentate Schiff bases (H~2~L) derived from biacetylmonoxime and acid hydrazides in methanol. The X‐ray structures of the complexes reveal unprecedented conversions of methyl groups in the biacetyl fragments of the Schiff bases into triphenyl‐vinyl‐λ^5^‐phosphane (=CHPHPh~3~) moieties in the transformed ligands (^t^L^–^). The metal centre in each complex is in a distorted octahedral N~2~OPCl~2~ coordination sphere made up of the meridionally spanning N,N,O‐donor ^t^L^–^, PPh~3~ and two mutually trans‐oriented chlorides. In their electronic spectra, the complexes each display four absorptions due to ligand‐to‐metal and ligand‐centred transitions in the 463–260 nm range. All the complexes are one‐electron paramagnetic (μ~eff.~ at 298 K = 1.81–2.06 μ~B~) and display rhombic EPR spectra in frozen (120 K) dichloromethane/toluene (1:1) solutions. Cyclic voltammograms of the complexes in dimethylformamide solutions show substituent‐sensitive, quasi‐reversible Ru^IV^/Ru^III^ and Ru^III^/Ru^II^ couples in the potential ranges of 0.46 to 0.54 V and –0.53 to –0.42 V (vs. Ag/AgCl), respectively.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)