كمپلكس هاي تك هسته اي و دو هسته اي رنيم ﴿I﴾ و كاربرد آنها به عنوان فتوكاتاليست هاي ويژه براي كاهش Co2 به ‍Co

چكيده انگليسي :

Mono and di nuclear Rhenium I Complexes and their Application as a Photocatalyst for Reduction of CO2 to CO Jamal Aldin Shakeri ja shakeriharandi@ch iut ac ir Date of Submission 2012 2 12 Department of Chemistry Isfahan University of Technology Isfahan 84156 83111 Iran Degree M S Language FarsiH Hadadzadeh Assoc Prof hadad@cc iut ac ir Abstract In this thesis two mononuclear complexes of Re I ReCl CO 3 py 2 and ReCl CO 3 phen dione and onedinuclear complex ReCl CO 3 tptzH Re CO 3 where tptz H is 2 4 6 tri pyridine 2 yl 2H 1 3 5 triazine 1 ide have been prepared and characterized by elemental analysis FT IR UV vis and NMR spectroscopies Solid statestructure of ReCl CO 3 tptzH Re CO 3 complex was determined by single crystal X ray crystallography Redcrystals of ReCl CO 3 tptzH Re CO 3 were grown by slow evaporation in chloroform and toluene This complexcrystallized in monoclinic crystal system with space group of P 21 c with the following unit cell parameters a 10 445 11 b 18 133 19 c 16 803 17 90 90 125 90 Z 4 andV 3 3182 6 In the dinuclear complex coordination geometry around each of Re I is distorted octahedral withbite angles of N 4 Re 2 N 5 75 N 2 Re 1 N 3 74 04 and N 2 Re 1 N 1 71 70 for the tptz H ligand Due to the configuration the pyridyl group on the sp3 hybridized C 1 is tilted to such an extent that it is almostperpendicular to both the central triazine ring 76 18 and the other pyridyl group 74 69 The partially saturated triazine ligand tptz H is coordinated as tridentate and bidentate chelate to each Re I Saturation of C 1 in tptz disturbs the aromaticity of triazine ring fllowed by two consecutive redox reactions Due to the activation of the dinuclear complexes in the presence of alumina an anation reaction occurs and onechloro ligand substiutes to one of Re I center The thermodynamic parameters 1H NMR 15N NMR 13C NMR IR and Raman spectra frontier orbitals FOs energy and modified structure of the unsaturated and partially saturated dinuclear complex were calculated by DFTmethod Photocatalytic activity of mono and dinuclear complexes for reduction of CO2 to CO in the presence of TEA TEOA and NHEt3Cl was also studied The results indicate a significant photocatalytic activity for each ofcomplexes Two catalytic cycles were proposed for reduction of CO2 to CO by these complexes In this catalyticcycles Under photochemical conditions the catalyst is initially excited with incident light which allows for ametal to ligand charge transfer Back electron transfer is prevented by excited state quenching with triethylamine TEA This results in the radical ion pair ReCl CO 3 tptzH Re CO 3 and Et3N which is the beginning of ourcatalytic cycle Both radical ions must undergo immediate reaction to continue the process Radical anion rheniumdissociates to a rhenium radical plus chloride while Et3N transfers a proton to a second molecule of TEA generating a neutral radical CH3C HNEt2 and the triethylammonium ion The two radicals then undergo adisproportionation reaction through TS1 to generate rhenium hydride and diethylvinylamine At this point insertionof CO2 into the Re H bond via TS2 yields rhenium complex with Re O bond This step forms the critical C H bond Dissociation of Re O bond yields formate rhenium cation The final step regenerates catalyst through reassociationof rhenium cation with chloride KeywordRhenium I complexes polypyridyl ligand redox reaction computational chemistry photocatalytic reaction reduction of CO2

شاكري، جمال الدين

كمپلكس هاي تك هسته اي و دو هسته اي رنيم ﴿I﴾ و كاربرد آنها به عنوان فتوكاتاليست هاي ويژه براي كاهش Co2 به ‍Co

ليگاندهاي پلي پيريديلي , واكنش ردوكس , شيمي محاسباتي