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[Ru(PPh 3 ) 3 Cl 2 ]‐Mediated Transformation of –CH 3 into =CHPHPh 3 in Biacetylmonoxime Acetyl‐/Aroylhydrazones: Ruthenium(III) Complexes with the Transformed Ligands
Author(s) -
Raveendran Raji,
Pal Samudranil
Publication year - 2008
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.200800765
Subject(s) - chemistry , ruthenium , ligand (biochemistry) , octahedron , dichloromethane , substituent , toluene , electron paramagnetic resonance , dimethylformamide , crystallography , transition metal , metal , coordination sphere , medicinal chemistry , stereochemistry , crystal structure , solvent , organic chemistry , catalysis , biochemistry , physics , receptor , nuclear magnetic resonance
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)