title: Electron transfer reaction of oxo(salen)chromium(V) ion with anilines.
abstract: The kinetics of oxidation of 16 meta-, ortho-, and para-substituted anilines with nine oxo(salen)chromium(V) ions have been studied by spectrophotometric, ESIMS, and EPR techniques. During the course of the reaction, two new peaks with lambda(max) at 470 and 730 nm appear in the absorption spectrum, and these peaks are due to the formation of emeraldine forms of oligomers of aniline supported by the ESIMS peaks with m/z values 274 and 365 (for the trimer and tetramer of aniline). The rate of the reaction is highly sensitive to the change of substituents in the aryl moiety of aniline and in the salen ligand of chromium(V) complexes. Application of the Hammett equation to analyze kinetic data yields a rho value of -3.8 for the substituent variation in aniline and +2.2 for the substituent variation in the salen ligand of the metal complex. On the basis of the spectral, kinetic, and product analysis studies, a mechanism involving an electron transfer from the nitrogen of aniline to the metal complex in the rate controlling step has been proposed. The Marcus equation has been successfully applied to this system, and the calculated values are compliant with the measured values.
authors.affiliation: Department of Chemistry, The American College, Madurai-625 002, India.
authors.forename: Sundarsingh
authors.initials: S
authors.lastname: Premsingh
authors.forename: Natarajan Sathiyamoorthy
authors.initials: NS
authors.lastname: Venkataramanan
authors.forename: Seenivasan
authors.initials: S
authors.lastname: Rajagopal
authors.forename: Shama P
authors.initials: SP
authors.lastname: Mirza
authors.forename: Mariappanadar
authors.initials: M
authors.lastname: Vairamani
authors.forename: P Sambasiva
authors.initials: PS
authors.lastname: Rao
authors.forename: K
authors.initials: K
authors.lastname: Velavan
mesh_terms: D000181:Acrylonitrile / Q000737:chemistry; D000814:Aniline Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D002857:Chromium / Q000737:chemistry*; D004563:Electrochemistry; D004583:Electrons; D007700:Kinetics; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D010084:Oxidation-Reduction; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods
chemical_list: D000814:Aniline Compounds; D009942:Organometallic Compounds; D002857:Chromium; D000181:Acrylonitrile