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Zirconium Complexes (zirconium + complex)
Selected AbstractsChemInform Abstract: A Zwitterionic Zirconium Complex that Catalyzes Hydroamination of Aminoalkenes at Room Temperature.CHEMINFORM, Issue 19 2010Kuntal Manna Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Storable, Powdered Chiral Zirconium Complex for Asymmetric Aldol and Hetero Diels,Alder Reactions.CHEMINFORM, Issue 38 2007Kazutaka Seki Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] Silica-Supported Zirconium Complexes and their Polyoligosilsesquioxane Analogues in the Transesterification of Acrylates: Part 1.ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 13 2009Characterization, Synthesis Abstract Various silica-supported acetylacetonate and alkoxy zirconium(IV) complexes have been prepared and characterized by quantitative chemical measurements of the surface reaction products, quantitative surface microanalysis of the surface complexes, in situ infrared spectroscopy, CP-MAS 13C,NMR spectroscopy and EXAFS. The complex (SiO)Zr(acac)3 (acac=acetylacetonate ligand) (1) can be obtained by reaction of zirconium tetraacetylacetonate [Zr(acac)4] with a silica surface previously dehydroxylated at 500,°C. The complexes (SiO)3Zr(acac) (2) and (SiO)3Zr(O- n- Bu) (n- Bu=butyl ligand) (3) can be synthesized by reaction of (SiO)3ZrH with, respectively, acetylacetone and n -butanol at room temperature. The spectroscopic data, including EXAFS spectroscopy, confirm that in compound 1 the zirconium is linked to the surface by only one SiOZr bond whereas in the case of compounds 2 and 3 the zirconium is linked to 3 surface oxygen atoms which are sigma bonded. EXAFS data indicate also that the acetylacetonate ligands behave as chelating ligands leading to a hepta-coordination around the zirconium atom in 1 and a penta-coordination in 2. In order to provide a molecular analogue of 1, the synthesis of the following polyoligosilsesquioxane derivative (c -C5H9)7Si8O12(CH3)2Zr(acac)3 (1,) was achieved. The compound 1, is obtained by reacting (c -C5H9)7Si8O11(CH3)2(OH), 4, with an equimolecular amount of Zr(acac)4. In the same manner, syntheses of complexes (c -C5H9)7Si7O12Zr(acac) (2,) and of (c-C5H9)7Si7O12Zr(O- n- Bu) (3,) were achieved by reaction of the unmodified trisilanol, (c -C5H9)7Si7O9(OH)3, with respectively Zr(acac)4 and Zr(O- n- Bu)4 at 60,°C in tetrahydrofuran. Compounds 1,, 2, and 3, can be considered as good models of 1, 2 and 3 since their spectroscopic properties are comparable with those of the surface complexes. The synthetic results obtained will permit us to study the catalytic properties of these surface complexes and of their molecular analogues with the ultimate goal of delineating clear structure-activity relationships. [source] Silica-Supported Zirconium Complexes and their Polyoligosilsesquioxane Analogues in the Transesterification of Acrylates: Part 2.ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 13 2009Activity, Recycling, Regeneration Abstract The catalytic activity of both supported and soluble molecular zirconium complexes was studied in the transesterification reaction of ethyl acrylate by butanol. Two series of catalysts were employed: three well defined silica-supported acetylacetonate and n -butoxy zirconium(IV) complexes linked to the surface by one or three siloxane bonds, (SiO)Zr(acac)3 (1) (SiO)3Zr(acac) (2) and (SiO)3Zr(O- n -Bu) (3), and their soluble polyoligosilsesquioxy analogues (c -C5H9)7Si8O12(CH3)2Zr(acac)3 (1,), (c -C5H9)7Si7O12Zr(acac) (2,), and (c -C5H9)7Si7O12Zr(O- n -Bu) (3,). The reactivity of these complexes were compared to relevant molecular catalysts [zirconium tetraacetylacetonate, Zr(acac)4 and zirconium tetra- n -butoxide, Zr(O- n- Bu)4]. Strong activity relationships between the silica-supported complexes and their polyoligosilsesquioxane analogues were established. Acetylacetonate complexes were found to be far superior to alkoxide complexes. The monopodal complexes 1 and 1, were found to be the most active in their respective series. Studies on the recycling of the heterogeneous catalysts showed significant degradation of activity for the acetylacetonate complexes (1 and 2) but not for the less active tripodal alkoxide catalyst, 3. Two factors are thought to contribute to the deactivation of catalyst: the lixivation of zirconium by cleavage of surface siloxide bonds and exchange reactions between acetylacetonate ligands and alcohols in the substrate/product solution. It was shown that the addition of acetylacetone to the low activity catalyst Zr(O- n- Bu)4 produced a system that was as active as Zr(acac)4. The applicability of ligand addition to heterogeneous systems was then studied. The addition of acetylacetone to the low activity solid catalyst 3 produced a highly active catalyst and the addition of a stoichiometric quantity of acetylacetone at each successive batch catalytic run greatly reduced catalyst deactivation for the highly active catalyst 1. [source] ChemInform Abstract: Titanium and Zirconium Complexes with Helical Bis(phenolato) Ligands as Hydroamination Catalysts.CHEMINFORM, Issue 8 2008Klaudia Marcsekova Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Facile Cyclometalation Reactions of Cp,Zirconium Complexes with Weakly Lewis Acidic Pendent Boron FunctionalitiesCHEMISTRY - A EUROPEAN JOURNAL, Issue 33 2009Marion Emmert Dipl.-Chem. Intramolecular hydroboration: Representative examples of Group,4 metallocene methyl complexes, including their synthesis, structure, and reactivity are discussed. The figure shows the thermolysis of the tethered bifunctional Zr/B compound 1, which results in the formation of "tucked-in" complex 2 with loss of MeBBN. [source] Chiral Fluorous Dialkoxy-Diamino Zirconium Complexes: Synthesis and Use in Stereospecific Polymerization of 1-HexeneCHEMISTRY - A EUROPEAN JOURNAL, Issue 3 2007Evgueni Kirillov Dr. Abstract New catalysts for the isospecific polymerization of 1-hexene based on cationic zirconium complexes incorporating the tetradentate fluorous dialkoxy-diamino ligands [OC(CF3)2CH2N(Me)(CH2)2N(Me)CH2C(CF3)2O]2, [(ON2NO)2,] and [OC(CF3)2CH2N(Me)(1R,2R -C6H10)N(Me)CH2C(CF3)2O]2, [(ONCyNO)2,] have been developed. The chiral fluorous diamino-diol [(ONCyNO)H2, 2] was prepared by ring-opening of the fluorinated oxirane (CF3)2COCH2 with (R,R)- N,N, -dimethyl-1,2-cyclohexanediamine. Proligand 2 reacts cleanly with [Zr(CH2Ph)4] and [Ti(OiPr)4] precursors to give the corresponding dialkoxy complexes [Zr(CH2Ph)2(ONCyNO)] (3) and [Ti(OiPr)2(ONCyNO)] (4), respectively. An X-ray diffraction study revealed that 3 crystallizes as a 1:1 mixture of two diastereomers (,- 3 and ,- 3), both of which adopt a distorted octahedral structure with trans -O, cis -N, and cis -CH2Ph ligands. The two diastereomers ,- 3 and ,- 3 adopt a C2 -symmetric structure in toluene solution, as established by NMR spectroscopy. Cationic complexes [Zr(CH2Ph)(ON2NO)(THF)n]+ (n=0, anion=[B(C6F5)4],, 5; n=1, anion=[PhCH2B(C6F5)3],, 6) and [Zr(CH2Ph)(ONCyNO)(THF)]+[PhCH2B(C6F5)3], (7) were generated from the neutral parent precursors [Zr(CH2Ph)2(ON2NO)] (H) and [Zr(CH2Ph)2(ONCyNO)] (3), and their possible structures were determined on the basis of 1H, 19F, and 13C NMR spectroscopy and DFT methods. The neutral zirconium complexes H and 3 (,- 3/,- 3 mixture), when activated with B(C6F5)3 or [Ph3C]+[B(C6F5)4],, catalyze the polymerization of 1-hexene with overall activities of up to 4500,kg,PH,mol,Zr,1,h,1, to yield isotactic-enriched (up to 74,% mmmm) polymers with low-to-moderate molecular weights (Mw=4800,47,200) and monodisperse molecular-weight distributions (Mw/Mn=1.17,1.79). [source] Copolymerization of Ethylene/1-hexene and Polymerization of Propylene with Cp-indenyl Zirconium ComplexesCHINESE JOURNAL OF CHEMISTRY, Issue 8 2005Zhang Yong Abstract Complexes (R1Cp)(R2Ind)ZrCl2, the catalysts previously reported active for ethylene polymerization showed high activity in ethylene/1-hexene copolymerization and propylene polymerization in the presence of MAO. The content of 1-hexene in copolymers ranged from 1.2% to 3.2%. In propylene polymerization the complex 1 showed the highest activity, up to 1.2×106 g of polypropylene per mol of catalyst per hour. Based on the analysis of NMR spectral data, the relationships between complex structures and polymerization results were explored. [source] Synthesis of a new zirconium catalyst for ethylene polymerizationJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 11 2008Fabiana De C. Fim Abstract A novel complex dichlorobis(2-ethyl-3-hydroxy-4-pyrone)zirconium(IV) (ZrCl2(ethylpyrone)2) was synthesized. Complexation of the pyrone ligand to the zirconium was confirmed by UV, 1H and 13C-NMR, and electrochemical studies. NMR showed the presence of four isomers and density functional theory calculations indicated that the main isomer had a cis configuration. The catalyst was shown to be active in ethylene polymerization in the presence of the cocatalyst methylaluminoxane. The highest catalyst activity for the zirconium complex was achieved at Al/Zr = 2500, 70 °C and when a small concentration of catalyst was used (1 ,mol). © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 3830,3841, 2008 [source] A novel titanium,,-O,zirconium complex: bis(,-methyliminodiethanolato-1,3O,N,O,;1:2,2O)(methyliminodiethanolato-2,3O,N,O,)dipropanolato-1,O,2,O -titanium(IV)zirconium(IV)ACTA CRYSTALLOGRAPHICA SECTION C, Issue 10 2002Graeme J. Gainsford The title compound, [TiZr(C5H11NO2)3(C3H7O)2], contains three methyliminodiethanolate ligands, two in different ,-oxo bridging coordination modes and one bound only to the Ti atom. The Ti and Zr atoms have distorted octahedral and pentagonal,bipyramidal coordinations, respectively, which share edges. As well as some conformational disorder in the carbon chains, there is chemical disorder at one Ti site, with a mix of n - and isopropanolate ligands. [source] Preparation of Diamidochloro(cyclopentadienyl)titanium Derivatives as Pre-Catalysts for Olefin Polymerization , X-ray Molecular Structure of [Ti(,5 -C5H5){1,2-C6H4(NCH2CH2CH3)2}Cl] and [Ti{,5 -C5H4(SiMe3)}{1,2-C6H4(NCH2CH2CH3)2}Cl]EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 15 2004Vanessa Tabernero Abstract The synthesis of N,N,-alkyl 1,2-phenylenediamines 1,2-C6H4(NHR)2 [R = CH2CH2CH3 (nPr), CH2tBu (Np)] was carried out in three steps by lithiation of the primary 1,2-phenylenediamine, reaction with the appropriate acyl chloride and reduction with LiAlH4. The addition of nBuLi to a stirred solution of N,N,-alkyl diamines in cold hexane resulted in the immediate deposition of the corresponding lithium salts, which react with [MCpR,Cl3] to give the diamidochloro(,5 -cyclopentadienyl)titanium and -zirconium complexes [MCpR,{1,2-C6H4(NR)2}Cl] (4,10) [M = Ti, Zr; CpR, = ,5 -C5H5, ,5 -C5(CH3)5, ,5 -C5H4(SiMe3); R = nPr, Np]. The compound [Ti(,5 -C5H5){1,2-C6H4(NnPr)2}Cl] (3) was obtained by treatment of [Ti(,5 -C5H5)Cl3] with 1,2-C6H4(NHnPr)2 in the presence of NEt3 in toluene. All the reported compounds were characterized by the usual analytical and NMR spectroscopic methods. The molecular structures of 3 and 7 were determined by single-crystal X-ray crystallography. The compounds described here were further investigated as potential olefin polymerization catalysts. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source] Silica-Supported Zirconium Complexes and their Polyoligosilsesquioxane Analogues in the Transesterification of Acrylates: Part 2.ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 13 2009Activity, Recycling, Regeneration Abstract The catalytic activity of both supported and soluble molecular zirconium complexes was studied in the transesterification reaction of ethyl acrylate by butanol. Two series of catalysts were employed: three well defined silica-supported acetylacetonate and n -butoxy zirconium(IV) complexes linked to the surface by one or three siloxane bonds, (SiO)Zr(acac)3 (1) (SiO)3Zr(acac) (2) and (SiO)3Zr(O- n -Bu) (3), and their soluble polyoligosilsesquioxy analogues (c -C5H9)7Si8O12(CH3)2Zr(acac)3 (1,), (c -C5H9)7Si7O12Zr(acac) (2,), and (c -C5H9)7Si7O12Zr(O- n -Bu) (3,). The reactivity of these complexes were compared to relevant molecular catalysts [zirconium tetraacetylacetonate, Zr(acac)4 and zirconium tetra- n -butoxide, Zr(O- n- Bu)4]. Strong activity relationships between the silica-supported complexes and their polyoligosilsesquioxane analogues were established. Acetylacetonate complexes were found to be far superior to alkoxide complexes. The monopodal complexes 1 and 1, were found to be the most active in their respective series. Studies on the recycling of the heterogeneous catalysts showed significant degradation of activity for the acetylacetonate complexes (1 and 2) but not for the less active tripodal alkoxide catalyst, 3. Two factors are thought to contribute to the deactivation of catalyst: the lixivation of zirconium by cleavage of surface siloxide bonds and exchange reactions between acetylacetonate ligands and alcohols in the substrate/product solution. It was shown that the addition of acetylacetone to the low activity catalyst Zr(O- n- Bu)4 produced a system that was as active as Zr(acac)4. The applicability of ligand addition to heterogeneous systems was then studied. The addition of acetylacetone to the low activity solid catalyst 3 produced a highly active catalyst and the addition of a stoichiometric quantity of acetylacetone at each successive batch catalytic run greatly reduced catalyst deactivation for the highly active catalyst 1. [source] Titanium and zirconium complexes containing modified TREN ligands for the polymerization of 1-alkenes,A comparative studyJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 23 2007Padmanabhan Sudhakar Abstract The titanium and zirconium complexes in C3 and Cs symmetric forms synthesized from corresponding aminotriols in combination with MAO polymerized 1-hexene in a controlled manner. When the polymerization temperature was lowered, they gave high molecular weight monodisperse polyhexene with narrow polydispersities indicating quazi-living systems. The isotactic polyhexene obtained from C3 titanium catalyst has the molecular weight of around 46,500 with PDI of 1.3 and the hemi-isotactic polymer from Cs titanium catalyst has the molecular weight of around 617,000 with PDI of 1.3. The analogues zirconium complexes upon activation with MAO polymerize hexene to give polyhexene having molecular weight of 53,000 (C3) and 626,000 (pseudo-Cs) with PDI ranging from 1.2 to 1.4. The MIX-titanium catalyst prepared from the 50:50 mixture of aminotriols was also able to polymerize 1-hexene and the GPC traces of the polyhexene suggests that even though the catalyst was formed from the mixture of aminotriols, the C3 and Cs symmetry of the catalysts retain its originality avoiding the formation of aggregates or polymeric forms. When one of the arms of aminotriol was methylated yield C2 and meso aminodiol ligands and their corresponding titanium and zirconium complexes gave higher molecular weight polyhexenes with lower PDI (C2 -Zr- Mn: 260,000; PDI: 1.05,1.10; mesoZr- Mn: 220,000; PDI: 1.05,1.10) possibly suggesting that these systems are close to living systems. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 5470,5479, 2007 [source] Highly active copolymerization of ethylene with 10-undecen-1-ol using phenoxy-based zirconium/methylaluminoxane catalystsJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 23 2005Xiaofan Zhang Abstract Activated with methylaluminoxane (MAO), phenoxy-based zirconium complexes bis[(3- tBu-C6H3 -2-O)-CHNC6H5]ZrCl2, bis[(3,5-di- tBu-C6H2 -2-O)-PhCNC6H5] ZrCl2, and bis[(3,5-di- tBu-C6H2 -2-O)-PhCN(2-F-C6H4)]ZrCl2 for the first time have been used for the copolymerization of ethylene with 10-undecen-1-ol. In comparison with the conventional metallocene, the phenoxy-based zirconium complexes exhibit much higher catalytic activities [>107 g of polymer (mol of catalyst),1 h,1]. The incorporation of 10-undecen-1-ol into the copolymers and the properties of the copolymers are strongly affected by the catalyst structure. Among the three catalysts, complex c is the most favorable for preparing higher molecular weight functionalized polyethylene containing a higher content of hydroxyl groups. Studies on the polymerization conditions indicate that the incorporated commoner content in the copolymers mainly depends on the comonomer concentration in the feed. The catalytic activity is slightly affected by the Al(MAO)/Zr molar ratio but decreases greatly with an increase in the polymerization temperature. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 5944,5952, 2005 [source] Chiral Fluorous Dialkoxy-Diamino Zirconium Complexes: Synthesis and Use in Stereospecific Polymerization of 1-HexeneCHEMISTRY - A EUROPEAN JOURNAL, Issue 3 2007Evgueni Kirillov Dr. Abstract New catalysts for the isospecific polymerization of 1-hexene based on cationic zirconium complexes incorporating the tetradentate fluorous dialkoxy-diamino ligands [OC(CF3)2CH2N(Me)(CH2)2N(Me)CH2C(CF3)2O]2, [(ON2NO)2,] and [OC(CF3)2CH2N(Me)(1R,2R -C6H10)N(Me)CH2C(CF3)2O]2, [(ONCyNO)2,] have been developed. The chiral fluorous diamino-diol [(ONCyNO)H2, 2] was prepared by ring-opening of the fluorinated oxirane (CF3)2COCH2 with (R,R)- N,N, -dimethyl-1,2-cyclohexanediamine. Proligand 2 reacts cleanly with [Zr(CH2Ph)4] and [Ti(OiPr)4] precursors to give the corresponding dialkoxy complexes [Zr(CH2Ph)2(ONCyNO)] (3) and [Ti(OiPr)2(ONCyNO)] (4), respectively. An X-ray diffraction study revealed that 3 crystallizes as a 1:1 mixture of two diastereomers (,- 3 and ,- 3), both of which adopt a distorted octahedral structure with trans -O, cis -N, and cis -CH2Ph ligands. The two diastereomers ,- 3 and ,- 3 adopt a C2 -symmetric structure in toluene solution, as established by NMR spectroscopy. Cationic complexes [Zr(CH2Ph)(ON2NO)(THF)n]+ (n=0, anion=[B(C6F5)4],, 5; n=1, anion=[PhCH2B(C6F5)3],, 6) and [Zr(CH2Ph)(ONCyNO)(THF)]+[PhCH2B(C6F5)3], (7) were generated from the neutral parent precursors [Zr(CH2Ph)2(ON2NO)] (H) and [Zr(CH2Ph)2(ONCyNO)] (3), and their possible structures were determined on the basis of 1H, 19F, and 13C NMR spectroscopy and DFT methods. The neutral zirconium complexes H and 3 (,- 3/,- 3 mixture), when activated with B(C6F5)3 or [Ph3C]+[B(C6F5)4],, catalyze the polymerization of 1-hexene with overall activities of up to 4500,kg,PH,mol,Zr,1,h,1, to yield isotactic-enriched (up to 74,% mmmm) polymers with low-to-moderate molecular weights (Mw=4800,47,200) and monodisperse molecular-weight distributions (Mw/Mn=1.17,1.79). [source] | ||||||||||||||||||||||