Synthesis, electronic structure and catalytic activity of ruthenium- iodo-carbonyl complexes with thioether containing NNS donor ligand Subrata Jana, Mahendra Sekhar Jana, Sujan Biswas, Chittaranjan Sinha ⇑ , Tapan Kumar Mondal ⇑ Inorganic Chemistry Section, Department of Chemistry, Jadavpur University, Kolkata 700032, India highlights  The ruthenium carbonyl complexes with redox noninnocent NNS donor ligand.  Cyclic voltammetric study.  Catalytic activity for the oxidation of alcohols to aldehydes/ketones.  DFT, NBO and TDDFT calculations. graphical abstract The ruthenium carbonyl complexes 1 and 2 with redox noninnocent NNS donor ligand have been synthe- sized and characterized by various analytical and spectroscopic techniques. Catalytic activity of the com- pounds has been investigated to the oxidation of primary and secondary alcohols to the corresponding adehyde and ketones respectively using N-methylmorpholine-N-oxide (NMO) as oxidant. The catalytic efficiency of 2 is greater than complex 1 and well correlate with the metal oxidation potential of the com- plexes. DFT, NBO and TDDFT calculations are employed to interpret the structural and electronic features of the complexes. article info Article history: Received 7 November 2013 Received in revised form 11 February 2014 Accepted 11 February 2014 Available online 24 February 2014 Keywords: Ruthenium carbonyl complex X-ray structure Electrochemistry Catalytic activity DFT method abstract The ruthenium carbonyl complexes 1 and 2 with redox noninnocent NNS donor ligand, 1-methyl-2- {(o-thiomethyl)phenylazo}imidazole (L) have been synthesized and characterized by various analytical and spectroscopic (IR, UV–Vis and 1 H NMR) techniques. The complexes exhibit a quasi-reversible one electron Ru(II)/Ru(III) oxidation couple at 1.11 V for 1 and 0.76 V for 2 along with two successive one electron ligand reductions. Catalytic activity of the compounds has been investigated to the oxidation of PhCH 2 OH to PhCHO, 2-butanol (C 4 H 9 OH) to 2-butanone, 1-phenylethanol (PhC 2 H 4 OH) to acetophe- none, cyclopentanol (C 5 H 9 OH) to cyclopentanone, cyclohexanol to cyclohexanone, cycloheptanol to cycloheptanone and cycloctanol to cycloctanone using N-methylmorpholine-N-oxide (NMO) as oxidant. The catalytic efficiency of 2 is greater than complex 1 and well correlate with the metal oxidation potential. DFT, NBO and TDDFT calculations in DFT/B3LYP/6-31G(d)/lanL2TZ(f) method are employed to interpret the structural and electronic features of the complexes. Ó 2014 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.molstruc.2014.02.029 0022-2860/Ó 2014 Elsevier B.V. All rights reserved. ⇑ Corresponding authors. Tel.: +91 03324146666; fax: +91 033 24146584. E-mail addresses: c_r_sinha@yahoo.com (C. Sinha), tkmondal@chemistry.jdvu. ac.in (T.K. Mondal). Journal of Molecular Structure 1065-1066 (2014) 52–60 Contents lists available at ScienceDirect Journal of Molecular Structure journal homepage: www.elsevier.com/locate/molstruc