title: Ruthenium(II) bipyridine complexes bearing new keto-enol azoimine ligands: synthesis, structure, electrochemistry and DFT calculations.
abstract: The novel azoimine ligand, Ph-NH-N=C(COCH3)-NHPh(C≡CH) (H2L), was synthesized and its molecular structure was determined by X-ray crystallography. Catalytic hydration of the terminal acetylene of H2L in the presence of RuCl3·3H2O in ethanol at reflux temperature yielded a ketone (L1=Ph-N=N-C(COCH3)=N-Ph(COCH3) and an enol (L2=Ph-N=N-C(COCH3)=N-PhC(OH)=CH2) by Markovnikov addition of water. Two mixed-ligand ruthenium complexes having general formula, trans-[Ru(bpy)(Y)Cl2] (1-2) (where Y=L1 (1) and Y=L2 (2), bpy is 2.2'-bipyrdine) were achieved by the stepwise addition of equimolar amounts of (H2L) and bpy ligands to RuCl3·3H2O in absolute ethanol. Theses complexes were characterized by elemental analyses and spectroscopic (IR, UV-Vis, and NMR (1D (1)H NMR, (13)C NMR, (DEPT-135), (DEPT-90), 2D (1)H-(1)H and (13)C-(1)H correlation (HMQC) spectroscopy)). The two complexes exhibit a quasi-reversible one electron Ru(II)/Ru(III) oxidation couple at 604 mV vs. ferrocene/ferrocenium (Cp2Fe(0/+)) couple along with one electron ligand reduction at -1010 mV. The crystal structure of complex 1 showed that the bidentate ligand L1 coordinates to Ru(II) by the azo- and imine-nitrogen donor atoms. The complex adopts a distorted trans octahedral coordination geometry of chloride ligands. The electronic spectra of 1 and 1+ in dichloromethane have been modeled by time-dependent density functional theory (TD-DFT).
authors.affiliation: Department of Chemistry, Hashemite University, P.O. Box 150459, Zarqa 13115, Jordan. Electronic address: manoaimi@hu.edu.jo.
authors.forename: Mousa
authors.initials: M
authors.lastname: Al-Noaimi
authors.affiliation: Department of Chemistry, The University of Jordan, Amman 11942, Jordan.
authors.forename: Firas F
authors.initials: FF
authors.lastname: Awwadi
authors.affiliation: Department of Chemistry, Hashemite University, P.O. Box 150459, Zarqa 13115, Jordan.
authors.forename: Ahmad
authors.initials: A
authors.lastname: Mansi
authors.affiliation: Fachbereich Chemie der Universität Konstanz, Universitätstraße 10, D-78457 Konstanz, Germany.
authors.forename: Obadah S
authors.initials: OS
authors.lastname: Abdel-Rahman
authors.affiliation: Chemistry Department, Yarmouk University, P.O. Box 566, Irbid, Jordan.
authors.forename: Ayman
authors.initials: A
authors.lastname: Hammoudeh
authors.affiliation: Department of Chemistry, AN-Najah National University, Nablus, Occupied Palestinian Territory.
authors.forename: Ismail
authors.initials: I
authors.lastname: Warad
mesh_terms: D001391:Azo Compounds / Q000737:chemistry*; D002384:Catalysis; D056831:Coordination Complexes / Q000138:chemical synthesis / Q000737:chemistry; D018360:Crystallography, X-Ray; D004563:Electrochemistry; D004583:Electrons; D007097:Imines / Q000737:chemistry*; D008024:Ligands; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D008968:Molecular Conformation; D011789:Quantum Theory; D012428:Ruthenium / Q000737:chemistry*; D013056:Spectrophotometry, Ultraviolet; D017550:Spectroscopy, Fourier Transform Infrared; D013816:Thermodynamics
chemical_list: D001391:Azo Compounds; D056831:Coordination Complexes; D007097:Imines; D008024:Ligands; D012428:Ruthenium
keywords: Catalytic hydration; DFT calculation; Electrochemistry; Keto–enol tautomers; Ruthenium; Spectroelectrochemistry