Synthesis and Reactivity of Rare Earth Metals [metal] Complexes with a Nitrogen Donor Ligand - read free eBook in online reader or directly download on the web page. Select files or add your book in reader. Download and read online ebook Synthesis and Reactivity of Rare Earth Metals [metal] Complexes with a Nitrogen Donor Ligand write by Ana-Mirela Neculai. This book was released on 2003. Synthesis and Reactivity of Rare Earth Metals [metal] Complexes with a Nitrogen Donor Ligand available in PDF, EPUB and Kindle.
Nitrogen Donor Ligands in the Coordination Chemistry of the Rare Earth and Alkaline Earth Metals
Nitrogen Donor Ligands in the Coordination Chemistry of the Rare Earth and Alkaline Earth Metals - read free eBook in online reader or directly download on the web page. Select files or add your book in reader. Download and read online ebook Nitrogen Donor Ligands in the Coordination Chemistry of the Rare Earth and Alkaline Earth Metals write by Jelena Jenter. This book was released on 2010-05-27. Nitrogen Donor Ligands in the Coordination Chemistry of the Rare Earth and Alkaline Earth Metals available in PDF, EPUB and Kindle. Bis(phosphinimino)methanide rare earth metal bisborohydrides, as illustrated in Scheme I, were successfully synthesized by salt metathesis reactions of [K{CH(PPh2NSiMe3)2}] with [Ln(BH4)3(THF)n] (Ln = Sc (n = 2); Ln = La, Nd, Lu (n = 3)) or in the case of yttrium by the reaction of [{(Me3SiNPPh2)2CH}YCl2]2 with NaBH4. Interestingly, the BH4- anions are ?3-coordinated in the solid state structures of 3, 4, 6 and 7, while for the scandium complex 5 two different conformational polymorphs were identified, in which either both BH4- groups are ?3-coordinated or one BH4- anion shows an ?2-coordination mode. Furthermore, complexes 3, 6 and 7 showed high activities in the ring-opening polymerization (ROP) of e-caprolactone (CL). At 0 °C, the molar mass distribution reached the narrowest values ever obtained for the ROP of CL initiated by a rare earth metal borohydride species. In collaboration with N. Meyer, rare earth metal chlorides and borohydrides of the 2,5-bis{N-(2,6-diisopropylphenyl)iminomethyl}pyrrolyl ligand were synthesized, as shown in Scheme II. The reaction of [(DIP2pyr)K] (10) with anhydrous neodymium trichloride afforded [(DIP2pyr)NdCl2(THF)]2 (12) which is dimeric in the solid state. Excitingly, the reaction of [(DIP2pyr)K] (10) with [Ln(BH4)3(THF)n] (Ln = Sc (n = 2); Ln = La, Nd, Lu (n = 3)) depends on the ionic radii of the center metals. For the larger rare earth metals lanthanum and neodymium, the expected products [(DIP2pyr)Ln(BH4)2(THF)2] (Ln = La (13), Nd (14)) were obtained; while for the smaller rare earth metals scandium and lutetium, an unusual redox reaction of a BH4- anion with one of the Schiff-base functions of the ligand was observed and the products [{DIP2pyr*-BH3}Ln(BH4)(THF)2] (Ln = Sc (15), Lu (16)) were formed (Scheme II). Moreover, the two neodymium containing complexes 12 and 14 were investigated as Ziegler-Natta catalysts for the polymerization of 1,3-butadiene to form poly-cis-1,4-butadiene, by using various cocatalyst mixtures. Very high activities and good selectivities were observed for 12. The 2,5-bis{N-(2,6-diisopropylphenyl)iminomethyl}pyrrolyl ligand was successfully introduced into the coordination chemistry of the divalent lanthanides and the alkaline earth metals. As shown in Scheme III, salt metathesis reactions of [(DIP2pyr)K] (10) with either anhydrous lanthanide diiodides or alkaline earth metal diiodides afforded the corresponding heteroleptic iodo complexes [(DIP2pyr)LnI(THF)3] (Ln = Sm (19), Eu (20), Yb (21)) or [(DIP2pyr)MI(THF)n] (M = Ca (24), Sr (22) (n = 3); Ba (23) (n = 4)). Surprisingly, all complexes 19-24 are monomeric in the solid state, independently from the ionic radii of their center metals. Instead of forming dimers, the coordination sphere of each metal center is satisfied by additionally coordinated THF molecules, which is a very rare structural motif in the chemistry of the larger divalent lanthanides and alkaline earth metals. While the (DIP2pyr)- ligands in 19-23 are ?3-coordinated in the solid state, for the calcium complex 24 an ?2-coordination mode was observed (Scheme III). Interestingly, the calcium complex 24 and the analogous ytterbium compound 21 show different structures in the solid state. In order to obtain catalytically active species, [(DIP2pyr)M{N(SiMe3)2}(THF)2] (M = Ca (25), Sr (26)) were prepared by the reaction of [(DIP2pyr)MI(THF)3] (M = Ca (24), Sr (22)) with [K{N(SiMe3)2}] (Scheme IV). Compounds 25 and 26 were investigated for the intramolecular hydroamination of aminoalkenes and one aminoalkyne. Unfortunately, both catalysts exhibit a limited reaction scope, caused by the formation of undesired side products by alkene isomerization and imine-enamine tautomerism. However, both compounds are active catalysts and show high yields and short reaction times. The highest activities were observed for the calcium complex 25 and can be compared to the results obtained with the ß-diketiminato calcium amide [{(DIPNC(Me))2CH}Ca{N(SiMe3)2}(THF)] as a catalyst. Finally, imidazolin-2-imide and cyclopentadienyl-imidazolin-2-imine rare earth metal alkyl complexes, synthesized by M. Tamm et al., were investigated for the intramolecular hydroamination of non-activated aminoalkenes and one aminoalkyne. Both compounds showed high selectivities and activities, and although they cannot compete with the metallocene analogues, the imidazolin-2-imide complexes are new and interesting examples for catalytically active post-metallocenes.
Synthesis of Chiral Rare Earth and Alkaline Earth Compounds
Synthesis of Chiral Rare Earth and Alkaline Earth Compounds - read free eBook in online reader or directly download on the web page. Select files or add your book in reader. Download and read online ebook Synthesis of Chiral Rare Earth and Alkaline Earth Compounds write by Meng He. This book was released on 2016-08-16. Synthesis of Chiral Rare Earth and Alkaline Earth Compounds available in PDF, EPUB and Kindle. The first chiral amidinate borohydride rare earth compounds and compounds based on (S)-HPEBA ((S,S)-N,N-bis-(1-phenylethyl)benzamidine) ligand were reported by Roesky et al. To continuing this work, the new chiral ligand (S)-HNEBA ((S,S)-N,N-bis-(1-naphthylethyl)benzamidine) were synthesized. The corresponding amidinate metal complexes were successfully obtained by amine elimination. The luminescent and magnetic properties of rare earth compounds were studied. Alkaline earth metal compounds have been extensively studied as catalysts in synthetic chemistry. However, chiral amidinate alkaline earth metal complexes have never been reported. Chiral amidinate ligand (S)-HPEBA was introduced into the coordination chemistry of the alkaline earth metal as well as divalent lanthanides, their catalytic activities in hydrophosphination have been investigated. The Ba compound showed high catalytic activities in the hydrophosphination reaction. Moreover, since rare earth metal COT complexes exhibit excellent SMM behavior, it is of great interest to study the magnetic behavior of COT amidinate complexes. Thus, amidine ligand (S)-HPEBA and (S)-HPETA are introduced into the corresponding COT amidinate complexes for magnetic properties studies. The Er Compound exhibited typical field-induced SMM behavior. Furthermore, inspired by the promising application of lanthanide SMMs and the research of SMMs based on sandwich type lanthanide complexes, a series of novel sandwich type complexes comprising of Pc and COT ligand were designed and synthesized.
Metal Complexes with Non-innocent N-donor Ligands: Molecular and Electronic Structures, Reactivity, and Application
Metal Complexes with Non-innocent N-donor Ligands: Molecular and Electronic Structures, Reactivity, and Application - read free eBook in online reader or directly download on the web page. Select files or add your book in reader. Download and read online ebook Metal Complexes with Non-innocent N-donor Ligands: Molecular and Electronic Structures, Reactivity, and Application write by . This book was released on 2006. Metal Complexes with Non-innocent N-donor Ligands: Molecular and Electronic Structures, Reactivity, and Application available in PDF, EPUB and Kindle. The present work comprises different aspects of coordination chemistry of non-innocent, or redox active, ligands. The most attention is given to the complexes of late transition metals as well as phthalocyanines of alkaline earth metals. The dissertation covers synthesis of complexes with non-innocent ligands and investigation of their molecular and electronic structures by set of methods including X-ray crystallography, EPR, NMR and electronic spectroscopy, electro- and magnetochemistry. Application such of complexes as catalysts for olefin polymerization or one-dimensional conducting materials is presented. I hope this work will be of interest as for synthetic chemists as well as for physical chemists having interest in application of variety of spectroscopic methods to allow deep understanding of coordination compounds with sophisticated electronic structures.
Synthesis, Structures and Reactivity of Rare Earth and Alkaline Earth Aryloxides
Synthesis, Structures and Reactivity of Rare Earth and Alkaline Earth Aryloxides - read free eBook in online reader or directly download on the web page. Select files or add your book in reader. Download and read online ebook Synthesis, Structures and Reactivity of Rare Earth and Alkaline Earth Aryloxides write by Joshua P. Townley. This book was released on 2010. Synthesis, Structures and Reactivity of Rare Earth and Alkaline Earth Aryloxides available in PDF, EPUB and Kindle. The focus of this Thesis is on the synthesis and characterisation of aryloxides of the lanthanoid and alkaline earth metals with an emphasis on structural characterisation. One of the key objectives has been to explore the boundaries of the redox transmetallation/protolysis (RTP) reaction (formerly known as redox transmetallation/ligand exchange), and this is the focus of Chapter 2. Redox transmetallation/protolysis reactions were performed in the non-donor solvents toluene and hexane, in which success has not previously been achieved, and the reaction rates monitored by 19F NMR spectroscopy. A donor-solvent free pathway is proposed in which an intermediate of the type [Ln(C6F5)2(HOAr)n] is formed, and plays a pivotal role in determining the speed of the reaction. The application of this method for the synthesis of homoleptic products was established by the synthesis of the known homoleptic compounds [Ln(2,6-dpp)3] (Ln = La, Pr, Nd), [Ba2(2,6- dpp)4] (2,6-dppH = 2,6-diphenylphenol) and [La(2,6-dip)3]2 (2,6-dipH = 2,6- diisopropylphenol) as well as the isolation of new compounds [La4(3,5-dbp)12(3,5- dbpH)] and [Nd4(3,5-dbp)12(3,5-dbpH)]/[Nd4(3,5-dbp)10(3,5-dbpH)4(OH)2] (3,5- dbpH = 3,5-di-tert-butylphenol). A series of lanthanoid aryloxide complexes of the type [Ln(2,4-dbp)3(THF)3] (Ln = La, Pr, Nd, Gd, Er) were prepared by RTP reactions with 2,4-di-tert-butylphenol (2,4-dbpH) and structurally characterised (Chapter 3). Reaction in DME with neodymium afforded the seven-coordinate [Nd(2,4-dbp)3(DME)2], while the dinuclear [Yb2(2,4-dbp)6(DME)2] was obtained by an analogous reaction with ytterbium. Recrystallising the THF derivatives from toluene or hexane resulted in the loss of THF and the formation of the dinuclear [Ln2(2,4-dbp)6(THF)2] (Ln = Nd, Er). The structurally similar [Nd2(2,4-dbp)6(2,4-dbpH)2] was the product of a thermally induced protolysis reaction between the metal and the phenol. A RTP reaction between ytterbium metal and 2-tert-butylphenol (2-tbpH) did not give a solid product, however, the complex [Yb2(2-tbp)6(THF)2] was obtained after crystallisation from toluene. Extending this chemistry to the heavy alkaline earth metals, calcium, strontium and barium resulted in the isolation of a group of new and interesting compounds ii (Chapter 4). Reactions in THF afforded [Ca(2,4-dbp)2(THF)4] and [Sr3(2,4- dbp)6(THF)6], while analogous reactions in DME gave the remarkable [Ca2(2,4- dbp)4(DME)5], containing a bridging molecule of DME, and the asymmetrically bridged [Sr2(2,4-dbp)4(DME)3]. Reactions with the larger barium yielded cluster complexes [Ba8(2,4-dbp)12(OH)4(DME)4] and [Ba8(2,4-dbp)12(OH)4]. Chapter 5 details the synthesis and characterisation of a series of lanthanoid and alkaline earth calixarene complexes. Reactions between the lanthanoid metals and p- But-calix[4]arene in the presence of bis(pentafluorophenyl)mercury yielded [Ln(calix[4]OH)(THF)]2 complexes (Ln = Nd, Yb). Attempts to isolate divalent products through the strategic use of the p-But-calix[4](Et)2(OH)2 were unsuccessful, instead affording a series of chloride-containing complexes of the type [Ln(calix[4]Et2)Cl(THF)]2, in which the presence of the chloride arose from contamination of the starting material. A reaction between strontium metal and p- But-calix[4](OH)4 in the presence of bis(pentafluorophenyl)mercury afforded [Sr4(calix[4](OH)2)4(OH2)4(THF)4] after partial hydrolysis. A number of compounds prepared in the course of this work ([Nd(2,4- dbp)3(THF)3], [Gd(2,4-dbp)3(THF)3], [Ca2(2,4-dbp)4(DME)5], [Sr2(2,4- dbp)4(DME)3]) as well as the known compounds [Yb(ttfpz)2(THF)4], [Sm(dippForm)2(THF)2], [La(xylForm)3(THF)], [Sm(xylForm)3] and [Sm(mesForm)3] were taken to Oxford University and tested as potential initiators for the ring-opening polymerisation of rac-lactide. All were found to be capable of initiating polymerisation, albeit with varying degrees of success. Most systems could be improved by the introduction of a co-initiator (or chain-transfer agent) such as benzyl alcohol or benzylamine to promote immortal polymerisation. Chapter 6 provides detailed discussions of the polymer features, as well as kinetics studies of the rate of polymerisation in the cases of [Nd(2,4-dbp)3(THF)3], [Ca2(2,4- dbp)4(DME)5], [Sr2(2,4-dbp)4(DME)3] and [Sm(dippForm)2(THF)2] in the presence of benzylamine. Furthermore a structure-activity relationship for the alkaline earth initiators is discussed.
