The development of efficient water oxidation catalysts(WOCs)is of key importance in order to drive sustainable reductive processes aimed at producing renewable fuels.Herein,two novel dinuclear complexes,[(Cp^*Ir)2(μ-...The development of efficient water oxidation catalysts(WOCs)is of key importance in order to drive sustainable reductive processes aimed at producing renewable fuels.Herein,two novel dinuclear complexes,[(Cp^*Ir)2(μ-κ^3-O,N,O-H4-EDTMP)](Ir-H4-EDTMP,H4-EDTMP^4-=ethylenediamine tetra(methylene phosphonate))and[(Cp^*Ir)2(μ-κ^3-O,N,O-EDTA)](Ir-EDTA,EDTA^4-=ethylenediaminetetraacetate),were synthesized and completely characterized in solution,by multinuclear and multidimensional NMR spectroscopy,and in the solid state,by single crystal X-Ray diffraction.They were supported onto rutile TiO2 nanocrystals obtaining Ir-H4-EDTMP@TiO2 and Ir-EDTA@TiO2 hybrid materials.Both molecular complexes and hybrid materials were found to be efficient catalysts for WO driven by NaIO4,providing almost quantitative yields,and TON values only limited by the amount of NaIO4 used.As for the molecular catalysts,Ir-H4-EDTMP(TOF up to 184 min^-1)exhibited much higher activity than Ir-EDTA(TOF up to 19 min^-1),likely owing to the higher propensity of the former to generate a coordination vacancy through the dissociation of a Ir–OP bond(2.123A,significantly longer than Ir–OC,2.0913A),which is a necessary step to activate these saturated complexes.Ir-H4-EDTMP@TiO2(up to 33 min^-1)and IrEDTA@TiO2(up to 41 min^-1)hybrid materials showed similar activity that was only marginally reduced in the second and third catalytic runs carried out after having separated the supernatant,which did not show any sign of activity,instead.The observed TOF values for hybrid materials are higher than those reported for analogous systems deriving from heterogenized mononuclear complexes.This suggests that supporting dinuclear molecular precursors could be a successful strategy to obtain efficient heterogenized water oxidation catalysts.展开更多
A new type of dinuclear titanocene was prepared by the reaction of bis(N,N-diethoxyl-aniline)-methane with pentamethylpentadienyl titanium trichloride in the presence of excessive triethylamine.The dinuclear titanocen...A new type of dinuclear titanocene was prepared by the reaction of bis(N,N-diethoxyl-aniline)-methane with pentamethylpentadienyl titanium trichloride in the presence of excessive triethylamine.The dinuclear titanocene displays catalytic activities towards the syndiospecific polymerization of styrene in the presence of modified methylaluminoxane(MMAO) as a cocatalyst,and produces higher molecular weight and syndiotacticity polystyrenes having bimodal molecular weight distribution than their mother complex Cp*TiCl3.Also,the study of polymerization behavior of dinuclear titanocene was carried out under the different polymerization temperature and Al/Ti molar ratio.展开更多
基金financially supported by PRIN 2015(20154X9ATP_004)University of Perugia and MIUR(AMIS,“Dipartimenti di Eccellenza–2018–2022”Program)+1 种基金INSTM and CIRCC for a post-doctoral grantUniversity of Perugia for hospitality and the Erasmus Programme for financial support。
文摘The development of efficient water oxidation catalysts(WOCs)is of key importance in order to drive sustainable reductive processes aimed at producing renewable fuels.Herein,two novel dinuclear complexes,[(Cp^*Ir)2(μ-κ^3-O,N,O-H4-EDTMP)](Ir-H4-EDTMP,H4-EDTMP^4-=ethylenediamine tetra(methylene phosphonate))and[(Cp^*Ir)2(μ-κ^3-O,N,O-EDTA)](Ir-EDTA,EDTA^4-=ethylenediaminetetraacetate),were synthesized and completely characterized in solution,by multinuclear and multidimensional NMR spectroscopy,and in the solid state,by single crystal X-Ray diffraction.They were supported onto rutile TiO2 nanocrystals obtaining Ir-H4-EDTMP@TiO2 and Ir-EDTA@TiO2 hybrid materials.Both molecular complexes and hybrid materials were found to be efficient catalysts for WO driven by NaIO4,providing almost quantitative yields,and TON values only limited by the amount of NaIO4 used.As for the molecular catalysts,Ir-H4-EDTMP(TOF up to 184 min^-1)exhibited much higher activity than Ir-EDTA(TOF up to 19 min^-1),likely owing to the higher propensity of the former to generate a coordination vacancy through the dissociation of a Ir–OP bond(2.123A,significantly longer than Ir–OC,2.0913A),which is a necessary step to activate these saturated complexes.Ir-H4-EDTMP@TiO2(up to 33 min^-1)and IrEDTA@TiO2(up to 41 min^-1)hybrid materials showed similar activity that was only marginally reduced in the second and third catalytic runs carried out after having separated the supernatant,which did not show any sign of activity,instead.The observed TOF values for hybrid materials are higher than those reported for analogous systems deriving from heterogenized mononuclear complexes.This suggests that supporting dinuclear molecular precursors could be a successful strategy to obtain efficient heterogenized water oxidation catalysts.
文摘A new type of dinuclear titanocene was prepared by the reaction of bis(N,N-diethoxyl-aniline)-methane with pentamethylpentadienyl titanium trichloride in the presence of excessive triethylamine.The dinuclear titanocene displays catalytic activities towards the syndiospecific polymerization of styrene in the presence of modified methylaluminoxane(MMAO) as a cocatalyst,and produces higher molecular weight and syndiotacticity polystyrenes having bimodal molecular weight distribution than their mother complex Cp*TiCl3.Also,the study of polymerization behavior of dinuclear titanocene was carried out under the different polymerization temperature and Al/Ti molar ratio.
