Homopolymerization of cyclic esters initiated by lanthanide isopropoxides supported by 2,2′‐ethylene‐bis(4,6‐di‐tert‐butylphenolate) ligands

Lanthanide isopropoxides supported by carbon‐bridged bisphenolate ligands of 2,2′‐ethylene‐bis(4,6‐di‐tert‐butylphenoxo) {[(EDBP)Ln(μ‐OPrⁱ)(THF)₂]₂, where Ln is Nd ( 1 ), Sm ( 2 ), or Yb ( 3 ) and THF is tetrahydrofuran} were synthesized by protic exchange reactions in high yields with Cp₃Ln compounds as raw materials, and complex 1 was structurally characterized. Complexes 1 – 3 were shown to be efficient initiators for the ring‐opening polymerization of ε‐caprolactone (ε‐CL) and 2,2‐dimethyltrimethylene carbonate (DTC). Complexes 1 – 3 could initiate the controlled polymerization of ε‐CL, and the polymerization rate was first‐order with respect to the monomer. The influence of the reaction conditions on the monomer conversion, molecular weight, and molecular weight distribution of the resultant polymers was investigated. End‐group analyses of the oligomers of ε‐CL and DTC showed that the polymerization underwent a coordination–insertion mechanism. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 4409–4419, 2006     

Metallorganische Verbindungen der Lanthanoide. 113. [(tert-Butylcyclopentadienyl)(cyclopentadienyl)dimethylsilan]-Komplexe ausgewählter Lanthanoide

Organometallic Compounds of the Lanthanides. 113. [(tert-Butylcyclopentadienyl)(cyclopentadienyl)dimethylsilane] Complexes of selected Lanthanides The reaction of [Me₂Si(C₅H₄)(tBuC₅H₃)]Li₂ with LnCl₃ (Ln = Y, Nd, Sm, Lu) in THF results in the formation of the chiral, dimeric complexes [Me₂Si(C₅H₄)(tBuC₅H₃)]Ln(μ-Cl)₂Li(THF)(Et₂O) [Ln = Y ( 1 ), Nd ( 2 ), Sm ( 3 ), Lu ( 4 )]. The ¹H-, ¹³C-NMR- and the mass spectra of the new compounds as well as the X-ray crystal structures of 2 a and 3 a were discussed.     

Metallorganische Verbindungen der Lanthanoide. 93 [1]. Tetramethylcyclopentadienyl-Komplexe ausgewählter 4f-Elemente

Organometallic Compounds of the Lanthanides. 93. Tetramethylcyclopentadienyl Complexes of Selected 4f-Elements The trichlorides of lanthanum, neodymium, samarium, and terbium react with Na(C₅Me₄H) in THF to yield the homoleptic complexes Ln(C₅Me₄H)₃ [Ln = La ( 1a ), Nd ( 1b ), Sm ( 1c ), Tb ( 1d )]. On the other hand the reactions of HoCl₃, TmCl₃, and LuCl₃ with Na(C₅Me₄H) result only with formation of the dicyclopentadienyl complexes (C₅Me₄H)₂LnCl(THF) [Ln = Ho ( 2e ), Tm ( 2f ), Lu ( 2h )]. The metallocenes (C₅Me₄H)₂Ln(THF)₂ [Ln = Sm ( 3c ), Yb ( 3g )] are obtained by the reactions of LnI₂ (Ln = Sm, Yb) with Na(C₅Me₄H). The ¹H- and ¹³C-NMR spectra as well as the X-ray crystal structure of the triscyclopentadienyl complexes 1 a and 1 c are discussed.     

Rare‐earth‐metal‐initiated polymerizations of (meth)acrylates and block copolymerizations of olefins with polar monomers

The organo‐rare‐earth‐metal‐initiated living polymerization of methyl methacrylate (MMA) was first discovered in 1992 with (C₅Me₅)₂LnR (where R is H or Me and Ln is Sm, Yb, Y, or La) as an initiator. These polymerizations provided highly syndiotactic (>96%) poly(methyl methacrylate) (PMMA) with a high number‐average molecular weight (M_n > 1000 × 10³) and a very narrow molecular weight distribution [weight‐average molecular weight/number‐average molecular weight (M_w/M_n) < 1.04] quantitatively in a short period. Bridged rare‐earth‐metallocene derivatives were used to perform the block copolymerization of ethylene or 1‐hexene with MMA, methyl acrylate, cyclic carbonate, or ?‐caprolactone in a voluntary ratio. Highly isotactic (97%), monodisperse, high molecular weight (M_n > 500 × 10³, M_w/M_n < 1.1) PMMA was first obtained in 1998 with [(Me₃Si)₃C]₂Yb. Stereocomplexes prepared by the mixing of the resulting syndiotactic and isotactic PMMA revealed improved physical properties. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 1955–1959, 2001     

Synthesis and Structure of 1—Cyclopentylindenyl Lanthanide（Ⅱ）Complexes and Their Catalytic Behavior for Polymerization of Acrylonitrile

The reaction between K(1‐C₅H₉C₉H₆) and anhydrous LnCl₃ (Ln=Sm, Yb) in the molar ratio of 2:1 in THF with subsequent treatment by Na‐K alloy afforded (1‐C₅H₉C₉H₆)₂Ln‐(THF)_n(Ln=Sm, n=1; Ln=Yb, n=2), while the reaction of Sml₂ with K(1‐C₅H₉C₉H₆) in the molar ratio of 1:2 in THF gave the anionic complex K(1‐C₅H₉C₉H₆)₃Sm(THF)₃. The X‐ray structure of (1‐C₅H₉C₉H₆)₂Yb(THF)₂ showed that central metal Yb is coordinated by two cyclopentadienyl rings of 1‐cyclopentylindenyls and two oxygen atoms from two tetrahydrofuran molecules to form pseudo‐tetrahedral coordinate geometry. All these complexes are active for the polymerization of acrylonitrile.     

Ethylene-Coordinative Chain-Transfer Polymerization-Induced Self-Assembly (CCTPISA)

Block copolymers based on ethylene (E) and butadiene (B) were prepared using the ansa-bis(fluorenyl) complex {Me₂Si(C₁₃H₈)₂Nd(BH₄)₂Li(THF)}₂ in combination with (n-Bu)(n-Oct)Mg (BOMAG) as a chain-transfer agent. The diblock copolymers incorporating a soft poly(ethylene-co-butadiene) segment, called ethylene butadiene rubber (EBR), and a hard polyethylene (PE) one were obtained by simply adjusting the different feeds of monomers during the polymerization. The soluble EBR block was formed first by feeding the catalytic system dissolved in toluene at 70 °C with a mixture of ethylene and butadiene (E/B molar ratio 80 : 20). Then the feeding was stopped leading to the consumption of a large part of the residual monomers. The reactor was finally fed with ethylene to form the PE block. By varying the molar mass of the latter, it is shown that the resulting soft-b-hard block copolymers can self-assemble simultaneously to the growth of the PE block in agreement with a polymerization-induced self-assembly (PISA) mechanism. The self-assembly is discussed considering the reaction conditions, the crystallization of the PE block, and the polymerization mechanism involved.     

Der Einfluß der Koordinationssphäre von Samarocenen auf die Synthese von flüssigkristallinen Polymethacrylaten

The Influence of the Coordination Sphere of Samarocenes on the Synthesis of Liquid Crystalline Polymethacrylates (C₅Me₅)₂Sm(THF)₂ ( 1 ) reacts with 1,3‐Diisopropyl‐4,5‐dimethylimidazoline‐2‐ylidene C₃N₂Me₂iPr₂ (iPr‐carben) with formation of (C₅Me₅)₂Sm(iPr‐carben) ( 3 ). The reaction of (C₅Me₄Et)₂Sm(THF)₂ ( 2 ) with Al₂Me₆ in toluene yields [(C₅Me₄Et)₂Sm(CH₃)Al(CH₃)₃]₂ ( 6 ). 3 and 6 were characterized by single crystal X‐ray structure analysis. Via living polymerization of mesogenic methacrylates with the organosamarium complexes 1 , 2 , 3 , (C₅Me₅)₂Sm(C₃H₅) ( 4 ), (C₅Me₅)₂Sm(CH₃)(THF) ( 5 ), 6 , and (C₅Me₄Et)₂SmCH(SiMe₃)₂ ( 7 ), liquid crystalline homo‐ and blockcopolymers were obtained with narrow molecular mass distribution indexes in high yield. Partial competitive mechanisms are observed dependend of the structure of the catalyst and the polarity of the solvents.     

Rare-earth metal allyl and hydrido complexes supported by an (NNNN)-type macrocyclic ligand: synthesis, structure, and reactivity toward biomass-derived furanics

The preparation and characterization of a series of neutral rare‐earth metal complexes [Ln(Me₃TACD)(η³‐C₃H₅)₂] (Ln=Y, La, Ce, Pr, Nd, Sm) supported by the 1,4,7‐trimethyl‐1,4,7,10‐tetraazacyclododecane anion (Me₃TACD^?) are reported. Upon treatment of the neutral allyl complexes [Ln(Me₃TACD)(η³‐C₃H₅)₂] with Brønsted acids, monocationic allyl complexes [Ln(Me₃TACD)(η³‐C₃H₅)(thf)₂][B(C₆X₅)₄] (Ln=La, Ce, Nd, X=H, F) were isolated and characterized. Hydrogenolysis gave the hydride complexes [Ln(Me₃TACD)H₂]_n (Ln=Y, n=3; La, n=4; Sm). X‐ray crystallography showed the lanthanum hydride to be tetranuclear. Reactivity studies of [Ln(Me₃TACD)R₂]_n (R=η³‐C₃H₅, n=0; R=H, n=3,4) towards furan derivatives includes hydrosilylation and deoxygenation under ring‐opening conditions.     

Synthesis,characterization and catalytic applications of triden-tate Schiff base derivatives of bis and mono(cyclopentadienyl)-lanthanocene complexes

Seven kinds of lanthanocene complexes were prepared by the reaction of tridentate Schiff base { N-(2-methoxyphenyI)sali-cylideneamine) with tris(cyclopentadienyl)lanthanide tetrahy-drofuranate or bis( cyclopentadienyl) lanthanide chloride te-trahydrofuranate in THF.All the complexes were characterized by MS,EA and IR respectively.The structure of {Cp2LnC14H13NO2) Ln=Sm,Dy,Y,Er} (1-4) was further confirmed by X-ray determination of Cp2Sm(C14H13NO2) (1) which indicates that the complex is monomeric in which central metal is coordinatively saturated by two cyclopentadienyl rings,two oxygens and one nitrogen of the ligand.The i-somerization of 1,5-hexadiene explains that complexes (1-4) isomerize this monomer into a mixture of 1,4-hexadiene,2,4-hexadiene,1,3-hexadiene,methylenecydopentane and methyl -cydopentene.Similarly complexes {CpLn(Cl)C14 H13NO2) (THF) (Ln=Sm,Dy,Y,Er)} (5-7) polymerize methyl-methacrylate (MMA.) to give polyMMA (PMMA) in 51.8% yield and high molecular weight (274×103),which shows nar     

Ring‐opening polymerization of 1‐methyltrimethylene carbonate by rare earth initiators

Ring‐opening polymerization of 1‐methyltrimethylene carbonate (MTMC) initiated by highly active single‐component rare earth tris(2,6‐di‐tert‐butyl‐4‐methylphenolate)s [Ln(OAr)₃, Ln = La, Dy, Y] or yttrium isopropoxide [Y(OiPr)₃] is reported for the first time. PolyMTMC (M_w = 8.4 × 10⁴, molecular weight distributions = 1.5) initiated by La(OAr)₃ at [MTMC]/[initiator] = 1000 was obtained with the yield over 99% in toluene within 1 h at 30 °C. Random and block copolymers of MTMC with ε‐caprolactone (CL), 2,2‐dimethyltrimethylene carbonate (DTC) or polyethylene glycol (PEG) including poly(MTMC‐r‐CL), poly(MTMC‐b‐CL), poly(MTMC‐r‐DTC), poly(MTMC‐b‐DTC), and poly(MTMC‐b‐PEG‐b‐MTMC) were synthesized. The differential scanning calorimetry results show that thermal behaviors of the polymers sensitively depend on their compositions and chain structures. Furthermore, the measurements of ¹H‐¹H COSY and density functional theory calculation are applied to investigate the mechanism. The polymerization of MTMC takes place according to a coordination‐insertion mechanism, and the ring is opened via acyl‐oxygen bond cleavage resulting in a Ln? O active center. There exist two ring‐opening modes of MTMC in which mode b , breaking the CH₂O? CO bond, is the major pathway. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3807–3815, 2010     

新型取代硅桥联茂稀土化合物的合成及在纳米级氢化钠助催化剂作用下高活性催化甲基丙烯酸甲酯聚合的研究

The synthesis and characterization of four new silicon-linked lanthanocene complexes with pendant phenyl groups on cyclopentadiene were reported. Based on the data of elemental analyses, MS and IR, the complexes were presumed to be unsolvated and dimeric complexes [Me2Si(C5H3CMe2C6H5)2LnC1]2 [Ln=Er (1), Gd (2), Sm (3), Dy (4)]. In conjunction with AlEt3 or sodium hydride as the co-catalyst, these complexes could efficiently catalyze the polymerization of methyl methacrylate (MMA). When the nanometric sodium hydride was used as a co-catalyst, the complexes were highly effective for the polymerization of MMA. At low temperature and in short time, in [MeESi(C5H3CMe2C6H5)2LnC1]2/NaH (nanometric) system, the polymer was obtained in more than 80% yield and the molecular weight was greater than 105. The activity reached that of organolanthanide hydride as a single-component catalyst. In ]MeESi(C5H3CMe2C6H5)2ErC1]2/Nail (nanometric) system, the effects of the molar ratio of MMA/catalyst and catalyst/co-catalyst, and the temperature on polymerization were studied.     

Organometallic Compounds of the Lanthanides. 127 [1] Synthesis of Monomeric Bis(cyclopentadienyl)lanthanide Tetrahydroborates with Bulky Cyclopentadienyl Ligands. Single Crystal X-ray Structures of [(η5-C5Me5)2SmBH4(THF)] and [(η5-C5Me4Et)2Y(μ-H)2BH2(THF)]

The trichlorides of yttrium, samarium, and lutetium react with 2 equivalents of Na[C₅H₄ ^tBu] and 1 equivalent of NaBH₄ to give [(η⁵-C₅H₄ ^tBu)₂LnBH₄(THF)] (Ln = Y ( 1 ), Sm ( 2 ), Lu ( 3 )) or with 2 equivalents of Na[C₅Me₄R] and 1 equivalent of NaBH₄ to form [(η⁵-C₅Me₄R)₂ · LnBH₄(THF)] (R = H, Ln = Y ( 4 ), Sm ( 5 ), Lu ( 6 ); R = Me, Ln = Y ( 7 ), Sm ( 8 ), Lu ( 9 ); R = Et, Ln = Y ( 10 ), Sm ( 11 ), Lu ( 12 ); R = ⁱPr, Ln = Y ( 13 ), Sm ( 14 ), Lu ( 15 )). The new compounds have been characterized by elemental analysis, NMR spectroscopy and mass spectrometry. The crystal structures of 8 and 10 were determined by single crystal X-ray diffraction.     

Synthese,Struktur und Reaktivität von Tris‐, Bis‐ und Mono(2,4‐dimethylpentadienyl)‐Komplexen des Neodyms,Lanthans und des Yttriums

The tris(2,4‐dimethylpentadienyl) complexes [Ln(η⁵‐Me₂C₅H₅)₃] (Ln = Nd, La, Y) are obtained analytically pure by reaction of the tribromides LnBr₃·nTHF with the potassium compound K(Me₂C₅H₅)(thf)_n in THF in good yields. The structural characterization is carried out by X‐ray crystal structure analysis and NMR‐spectroscopically. The tris complexes can be transformed into the dimeric bis(2,4‐dimethylpentadienyl) complexes [Ln₂(η⁵‐Me₂C₅H₅)₄X₂] (Ln, X: Nd, Cl, Br, I; La, Br, I; Y, Br) by reaction with the trihalides THF solvates in the molar ratio 2:1 in toluene. Structure and bonding conditions are determined for selected compounds by X‐ray crystal structure analysis and NMR‐spectroscopically in general. The dimer‐monomer equilibrium existing in solution was investigated NMR‐spectroscopically in dependence of the donor strength of the solvent and could be established also by preparation of the corresponding monomer neutral ligand complexes [Ln(η⁵‐Me₂C₅H₅)₂X(L)] (Ln, X, L: Nd, Br, py; La, Cl, thf; Br, py; Y, Br, thf). Finally the possibilities for preparation of mono(2,4‐dimethylpentadienyl)lanthanoid(III)‐dibromid complexes are shown and the hexameric structure of the lanthanum complex [La₆(η⁵‐Me₂C₅H₅)₆Br₁₂(thf)₄] is proved by X‐ray crystal structure analysis.     

Introduction of reactive functionality by the incorporation of divinylbiphenyl in ethylene copolymerization with styrene or 1‐hexene using aryloxo‐modified half‐titanocenes and MAO catalysts

An efficient introduction of vinyl group into poly (ethylene‐co‐styrene) or poly(ethylene‐co?1‐hexene) has been achieved by the incorporation of 3,3′‐divinylbiphenyl (DVBP) in terpolymerization of ethylene, styrene, or 1‐hexene with DVBP using aryloxo‐modified half‐titanocenes, Cp′TiCl₂(O?2,6‐ⁱPr₂C₆H₃) [Cp′ = Cp*, ^tBuC₅H₄, 1,2,4‐Me₃C₅H₂], in the presence of MAO cocatalyst, affording high‐molecular‐weight polymers with unimodal distributions. Efficient comonomer incorporations have been achieved by these catalysts, and the content of each comonomer could be varied by its initial concentration charged. The postpolymerization of styrene was initiated from the vinyl group remained in the side chain by treatment with n‐BuLi. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 2581–2587     

Bimetallic Rare Earth Alkyl Complexes Bearing Bridged Amidinate Ligands: Synthesis and Activity for L-Lactide Polymerization

Four novel bridged‐amidines H₂L {1,4‐R¹[C(=NR²)(NHR²)]₂ [R¹=C₆H₄, R²=2,6‐ⁱPr₂C₆H₃ (H₂L¹); R¹=C₆H₄, R²=2,6‐Me₂C₆H₃ (H₂L²); R¹=C₆H₁₀, R²=2,6‐ⁱPr₂C₆H₃ (H₂L³); R¹=C₆H₁₀, R²=2,6‐Me₂C₆H₃ (H₂L⁴)]} were synthesized in 65%–78% isolated yields by the condensation reaction of dicarboxylic acid with four equimolar amounts of amines in the presence of PPSE at 180°C. Alkane elimination reaction of Ln(CH₂SiMe₃)₃(THF)₂ (Ln=Y, Lu) with 0.5 equiv. of amidine in THF at room temperature afforded the corresponding bimetallic rare earth alkyl complexes (THF)(Me₃SiCH₂)₂LnL¹Ln(CH₂SiMe₃)₂(THF) [Ln=Y ( 1 ), Lu ( 2 )], (THF)(Me₃SiCH₂)₂LnL²Ln‐ (CH₂SiMe₃)₂(THF) [Ln=Y ( 3 ), Lu ( 4 )], (THF)(Me₃SiCH₂)₂YL³Y(CH₂SiMe₃)₂(THF) ( 5 ), (THF)(Me₃SiCH₂)₂YL⁴‐ Y(CH₂SiMe₃)₂(THF) ( 6 ) in 72% –80% isolated yields. These neutral complexes showed activity towards L‐lactide polymerization in toluene at 70°C to give high molecular weight (M>10⁴) and narrow molecular weight distribution (M_w/M_n≦1.40) polymers     

Komplexchemie P-reicher Phosphane und Silylphosphane. VIII. Zur unterschiedlichen Tendenz der Bildung von Chromcarbonyl-Komplexen silylierter-alkylierter Phosphane und Diphosphane

Transition Metal Complexes of P-rich Phosphanes and Silylphosphanes. VIII. Concerning the Different Tendencies of Silylated and Alkylated Phosphanes and Diphosphanes to Form Chromium Carbonyl Complexes The influence of the substituents Me₃Si tBu and Me in phosphanes and diphosphanes on the formation of complex compounds with Cr(CO)₅THF is investigated. tBu(Me₃Si)P? P(SiMe₃)₂ 1 and (tBu)₂P? P(SiMe₃)₂ 2, resp., react with Cr(CO)₅THF 4 at ?18°C by coordinating Cr(CO)₅ to the P(SiMe₃)₂ group to give tBu(Me₃Si)P? P^IV(SiMe₃), · Cr(CO)₅ 1 a, tBu(Me₃Si)P^IV? P^IV(SiMe₃)₂ · Cr(CO)₄ 1b and (tBu)₂P? P^IV(SiMe₃)₂ · Cr(CO)₅ 2a . In the reaction of 1 with 4 using a molar ratio of 1:2 at first 1 a is formed which reacts on to yield completely 1 b. In a mixture of the dissolved compounds (Me₃Si)₃P 5, (tBu)₃P 6 and (tBu)₃P? P(SiMe₃)₂ 2 only 5 and 6 react with Cr(CO)₅THF yielding (Me₃Si)₃P · Cr(CO)₅ and (tBu)₃P · Cr(CO)₅, but 2 does not yet react. In a solution of (Me₃Si)₃P 5, P₂Me₄ 7 and (Me₃Si)₂P? PMe₂ 3 only 5 and 7 react with Cr(CO)₅THF (0.25 to 1.5 equivalents with respect to 3) to give (Me₃Si)₃P · Cr(CO)₅, P₂Me₄ · Cr(CO)₅ and P₂Me₄ · 2Cr(CO)₅. The formation of complexes with Cr(CO)₅THF of the phosphanes 5 and 6 is clearly favoured as compared to the silylated diphosphanes 2 and 3 (not to P₂Me₄); the PR₂ groups (R = tBu, Me in 2 or 3 ) don't have a strong influence.     

Anionic lanthanide phenoxide complexes as novel single‐component initiators for the polymerization of ε‐caprolactone and trimethylene carbonate

The anionic lanthanide‐sodium‐2,6‐di‐tert‐butyl‐phenoxide complexes [Ln(OAr)₄][Na(DME)₃]·DME (Ln = Nd 1 (neodymium), Sm 2 (samarium), or Gd 3 (gadolium); DME = dimethoxyethane) were synthesized by the reaction of anhydrous LnCl₃ with 4 equiv of sodium‐2,6‐di‐tert‐butyl‐phenoxide NaOAr in high yields and structurally characterized. These complexes showed high catalytic activity in the ring‐opening polymerizations of ?‐caprolactone (?‐CL) and trimethylene carbonate (TMC). The catalytic activity profoundly depended on the lanthanide metals. The active order of Gd < Sm < Nd for the polymerization of ?‐CL and TMC was observed. The polymers obtained with these initiators all showed a unimodal molecular weight distribution, indicating that the [Ln(OAr)₄][Na(DME)₃]·DME anionic complexes could be used as single‐component initiators. The anionic complex was more efficient than the corresponding neutral complex, Ln(OAr)₃(THF)₂. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 1210–1218, 2007     

Polymerization of n‐phenyl maleimide by lanthanide complexes

N‐Phenyl maleimide (N‐PMI) was successfully polymerized by divalent rare‐earth complexes (ArO)₂Sm(THF)₄ (ArO = 2,6‐di‐tert‐butyl‐4‐methyl phenoxo‐; THF = tetrahydrofuran) and (Ar′O)₂Ln(THF)₃ (Ar′O = 2,6‐di‐tert‐butyl phenoxo‐; Ln = Sm, Yb, or Eu). The central metals greatly affected the reactivity, and the reactivity order was Sm(II) > Yb(II) > Eu(II). The activity of (Ar′O)₂Sm(THF)₃ was higher than that of (ArO)₂Sm(THF)₄. The polymerization yields were higher in THF than in other solvents, and the maximum yields were obtained around 25 °C. A proposed mechanism is discussed. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 3966–3972, 2005     

Ethylene‐Norbornene Terpolymerization with 5‐Vinyl‐2‐norbornene Using Single‐Site Catalysts

The incorporation of 5‐vinyl‐2‐norbornene (VNB) into ethylene‐norbornene copolymer was investigated with catalysts [Ph₂C(Fluo)(Cp)]ZrCl₂ ( 1 ), rac‐[Et(Ind)₂]ZrCl₂ ( 2 ), and [Me₂Si(Me₄Cp)^tBuN]TiCl₂ ( 3 ) in the presence of MAO by terpolymerizing different amounts of 5‐vinyl‐2‐norbornene with constant amounts of ethylene and norbornene at 60°C. The highest cycloolefin incorporations and highest activity in terpolymerizations were achieved with 1 . The distribution of the monomers in the terpolymer chain was determined by NMR spectroscopy. As confirmed by XRD and DSC analysis, catalysts 1 and 3 produced amorphous terpolymer, whereas 2 yielded terpolymer with crystalline fragments of long ethylene sequences. When compared with poly‐(ethylene‐co‐norbornene), VNB increased both the glass transition temperatures and molar masses of terpolymers produced with the constrained geometry catalyst whereas decreased those for the metallocenes.     

Synthese und Charakterisierung donor-funktionalisierter ansa-Metallocene von Yttrium,Neodym, Samarium,Erbium und Lutetium

Organometallic Compounds of the Lanthanides. 133 Synthesis and Characterization of donor-functionalised ansa -Metallocenes of Yttrium, Neodymium, Samarium, Erbium, and Lutetium The reaction of Me₂SiCl₂ with K[C₅H₄^tBu], Li[C₅H₄SiMe₃] or K[C₅H₃^tBuMe-3] followed by treatment with K[C₅H₄CH₂CH₂NMe₂] yields mixed substituted dicyclopentadienyldimethylsilanes which after double deprotonation with KH afford the dipotassium salts K₂[Me₂Si(C₅H₃^tBu-3)(C₅H₃CH₂CH₂NMe₂-3)] ( 1 ), K₂[Me₂Si · (C₅H₃SiMe₃-3)(C₅H₃CH₂CH₂NMe₂-3)] ( 2 ), and K₂[Me₂Si · (C₅H₂^tBu-3-Me-5)(C₅H₃CH₂CH₂NMe₂-3)] ( 3 ), respectively. The reaction of 1 , 2 , or 3 with LnCl₃(THF)_x (Ln = Y, La, Nd, Sm, Er, Lu) leads to the complexes [Me₂Si(C₅H₃^tBu-3) · (C₅H₃CH₂CH₂NMe₂-3)]LnCl [Ln = Y ( 4 a ), Sm ( 4 c ), Lu ( 4 e )], [Me₂Si(C₅H₃SiMe₃-3)(C₅H₃CH₂CH₂NMe₂-3)]LnCl [Ln = Y ( 5 a ), Sm ( 5 c ), Lu ( 5 e )], and [Me₂Si(C₅H₂^tBu-3-Me-5)(C₅H₃CH₂CH₂NMe₂-3)]LnCl [Ln = Y ( 6 a ), Nd ( 6 b ), Sm ( 6 c ), Er ( 6 d ), Lu ( 6 e )], respectively. Alkylation of 4 a , 4 c , 5 a , and 6 b , 6 e with LiCH₃, LiCH₂SiMe₃, and LiCH(SiMe₃)₂ produces the alkylmetallocenes [Me₂Si(C₅H₃^tBu-3) · (C₅H₃CH₂CH₂NMe₂-3)]LnR [R = CH₃, Ln = Y ( 7 a ), Sm ( 7 c ); R = CH₂SiMe₃, Ln = Y ( 8 a )], [Me₂Si(C₅H₃SiMe₃-3) · (C₅H₃CH₂CH₂NMe₂-3)]YCH₃ ( 9 a ), and [Me₂Si(C₅H₂^tBu3-Me-5)(C₅H₃CH₂CH₂NMe₂-3)]LnR (R = CH₃, Ln = Lu ( 10 e ); R = CH₂SiMe₃, Ln = Lu ( 11 e ); R = CH(SiMe₃)₂, Ln = Nd ( 12 b ), Lu ( 12 e )], respectively. All new compounds were characterized by elemental analyses, NMR spectroscopy and mass spectrometry. The molecular structure of 6 c and 6 e was determined by single crystal X-ray structure analysis.