Ethylene polymerization and ethylene/hexene copolymerizaion with vandium catalysts bearing thiophenolphosphine ligands

Vanadium(Ⅲ) complexes bearing thiophenol-phosphine ligands (2a-2b) (2-R-6-PPh2-C6H2S) VCl2(THF)2 (2a: R=H; 2b: R=Me3Si) were prepared from VCl3(THF)3 by treating with 1.0 equiv of the ligand in tetrahydrofuran in the presence of excess triethylamine. The two complexes were characterized by FTIR and mass spectra as well as elemental analyses. On activation with Et2AlCl, these complexes exhibited high catalytic activities (up to 22.1 kg PE/(mmolV·h·bar)) even at high temperature (70℃), and produced high molecular weight polymers with unimodal molecular weight distributions, indicating the polymerization took place in a single-site nature. This result may be attributed to benefits of introduction of second-row donor atoms for adjusting charge density of the vanadium centers. In addition, these complexes also exhibited high catalytic activities for ethylene/1-hexene copolymerization. Catalytic activity, comonomer incorporation and polymer molecular weight can be controlled in a wide range by the variation of catalyst structure and the reaction parameters such as Al/V molar ratio, comonomer feed concentration and polymerization reaction temperature.     

Ethylene (co-)polymerization by long-lifetime half-sandwich zirconium catalyst bearing a [SSO]-carborane ligand

Half-sandwich zirconium complex 3 containing tridentate carborane [S,S,O] ligand 2 [(HOC6H2R2-4,6)(CH2)SC(B10H10) C(Ph)2P=S, R=tBu] was synthesized by the reaction of CpZrCl3(Cp=η5-C5H5) with sodium salt of ligand 2. Zirconium complex 3 was characterized by elemental and NMR analyses. DFT calculations were also performed on complex 3 to analyze the stereochemistry. The results from DFT calculations indicate that structure S1, in which no sulfur atom bonds to the zirconium atom, exists at the lowest energy level. In the presence of methylaluminoxane(MAO), complex 3 exhibited good catalytic activities for ethylene polymerization and long life-time up to 10 h. Moreover, the complex 3/MAO system displayed excellent catalytic activities toword ethylene copolymerization with 1-hexene or polar olefins.     

Living polymerization of 1,3-butadiene catalyzed by half-titanocene complex bearing dibenzhydryl-substituted aryloxide ligand

Half-titanocene complexes bearing dibenzhydryl-substituted aryloxide ligands(2a-2d) were prepared. Among them, 2c adopted a three-legged distorted tetrahedral geometry evidenced by X-ray crystallography. The poly-1,3-butadiene with high molecular weight and narrow molecular weight distribution was obtained by using these complexes as the catalysts activated with methylaluminoxane(MAO). The catalytic activities of the complexes depended on their structures. The Ti―O―C bond in the complexes with large angle afforded them with higher activity, while Cp*-based complexes exhibited lower activities than the Cp-based analogues. The activity of complex increased with increasing the polymerization temperature while the selectivity remained no change, indicating the high thermal stability. Furthermore, the polymerization of 1,3-butadiene catalyzed by 2a/MAO at 0 °C has been found in a living fashion.     

Introduction of Constrained Cyclic Skeleton into β-Enaminoketonato Vanadium Complexes: A Strategy for Stabilization of Active Centre of Vanadium Catalyst for Ethylene Polymerization

Several novel mono( ?-enaminoketonato) vanadium complexes bearing constrained cyclic skeleton, including[(C6H5)C6H3C(O) = C(CH2)nCH = N ― Ar]VCl2(THF)2(V3a: n = 1, Ar = C6H5; V4a: n = 2, Ar = C6H5; V4b: n = 2, Ar =C6F5; V4c: n = 2, Ar =(C3H7)2C6H3; V5a: n = 3, Ar = C6H5), were synthesized and their structure and properties were characterized. The structures of V4 c and V5 a in solid-state were further confirmed by X-ray crystallographic analysis.Density functional theory(DFT) results indicated that these complexes showed enhanced steric hindrance around the metal center as compared with the acyclic analogues. Upon activation with Et2 Al Cl and in the presence of ethyl trichloroacetate as a reactivator, all of the complexes exhibited high catalytic activities(107 g PE/(mol V·h)) toward ethylene polymerization, and the obtained polymers exhibited unimodal distributions(Mw/Mn = 2.0-2.3) even produced at elevated temperatures(70-100 °C) and prolonged reaction time. When MAO was employed as a cocatalyst, they only showed moderate catalytic activities(105 g PE/(mol V·h)), but the resulting polymers had higher molecular weights(168-241 kg/mol). These vanadium complexes with cyclic skeleton also showed high catalytic activities toward ethylene/norbornene copolymerization. The produced copolymers displayed approximate alternating structure at high in-feed concentration of norbornene. The catalytic capabilities of these complexes could be tuned conveniently by varying ligand structure. Furthermore, the cyclic voltammetry results also proved that these complexes exhibited better redox stabilities than the complexes bearing linear skeleton.     

Zinc Complexes Supported by N,N-Dimethylaniline-arylamido Ligands： Synthesis,Characterization and Catalytic Properties for Ring-opening Polymerization of L-Lactide

The reaction of bidentate N,N-dimethylaniline-arylamido ligands,o-C6H4NMe2（CH2NHAr）（Ar =Ph,1a;2,6-Me2C6H3,1b; 2,6-Et2C6H3,1c; 2,6-ipr2C6H3,1d） with ZnEt2 yields the complexes o-C6H4（NMe2）（CH2NAr）ZnEt （2a-2d）,respectively.All the complexes were characterized by 1H and 13C NMR spectroscopy and elemental analyses.It was found that all the zinc complexes were efficient catalysts for the ring-opening polymerization of L-lactide in the presence of benzyl alcohol with good molecular weight control and narrow polydispersity.     

Syntheses of Some New Group 4 non-Cp Complexes Bearing Schiff-base, Thiophene Diamide Ligands Respectively and Their Catalytic Activities for a-Olefin Polymerization

Totally sixteen new titanium and zirconium non-Cp complexes supported by Schiff-base, or thiophene diamide ligands have been synthesized. The complexes are obtained by the reaction of M(OPr-i)4(M=Ti,Zr) with the corresponding Schiff-base ligand in 1:1 molar ratio in good yield. The thiophene diamide titanium complex has been prepared from trimethylsilyl amine [N,S,N] ligand and TiCl4 in toluene at 120℃. All complexes are well charac-terized by ^1H NMR, IR, MS and elemental analysis. When activated by excess methylaluminoxane (MAO), complexes show moderate catalytic activity for ethylene polymerization, and complex If (R^1=CH3,R^2=Br) exhibits the highest activity for ethylene and styrene polymerization. When the complexes were preactivated by triethylaluminum (TEA), both polymerization activities and syndiotacticity of the polymers were greatly improved.     

Syntheses, characterization and ethylene polymerization of half-sandwich group IV metal complexes with tridentate [O,N,S] ligands

A series of half-sandwich group IV metal complexes with tridentate monoanionic phenoxy-imine arylsulfide [O NS] ligand [2-Bu t 4-Me-6-((2-(SC 6 H 5)C 6 H 4 N = CHC 6 H 2 O)](La) and dianionic phenoxy-amine arylsulfide [O N S] ligand [2-Bu t 4-Me-6-((2-(SC 6 H 5)C 6 H 4 N-CH 2 C 6 H 2 O)] 2(Lb) have been synthesized and characterized.Lb was obtained easily in high yield by reduction of ligand La with excess LiAlH 4 in cool diethyl ether.Half-sandwich Group IV metal complexes CpTi[O NS]Cl 2(1a),CpZr[O NS]Cl 2(1b),CpTi[O N S]Cl(2a),CpZr[O N S]Cl(2b) and Cp * Zr[O N S]Cl(2c) were synthesized by the reactions of La and Lb with CpTiCl 3,CpZrCl 3 and Cp * ZrCl 3,and characterized by IR,1 H-NMR,13 C-NMR and elemental analysis.In addition,an X-ray structure analysis was performed on ligand Lb.The title Group IV half-sandwich bearing tridentate [O,N,S] ligands show good catalytic activities for ethylene polymerization in the presence of methylaluminoxane(MAO) as co-catalyst up to 1.58 × 10 7 g-PE.mol-Zr 1.h 1.The good catalytic activities can be maintained even at high temperatures such as 100 ℃ exhibiting the excellent thermal stability for these half-sandwich metal pre-catalysts.     

DEPENDENCE OF THE DISTRIBUTION OF ACTIVE CENTERS ON MONOMER IN SUPPORTED ZIEGLER-NATTA CATALYSTS

Distribution of active centers(ACD)of ethylene or 1-hexene homopolymerization and ethylene-1-hexene copolymerization with a MgCl_2/TiCl_4 type Z-N catalyst were studied by deconvolution of the polymer molecular weight distribution into multiple Flory components.Each Flory component is thought to be formed by a certain type of active center. ACD of ethylene-1-hexene copolymer with very low 1-hexene incorporation was compared with that of ethylene homopolymer to see the effect of introducingα-olefin on eth...     

Ethylene polymerization with novel phenoxy-imine catalysts bearing 4-vinylphenyl group

This contribution reports ethylene polymerization behavior of titanium complexes incorporating bis(phenoxyimine) ligands. Six phenoxy-imine Ti(IV) complexes {6-R1-2-[CH=N(2,6-difluoro-3,5-diR2-4-R3Ph)]C6H3O}2TiCl2(1: R1 = H, R2 = H, R3 = H; 2: R1 = H, R2 = H, R3 = 4-vinylphenyl; 3: R1 = CH3, R2 = H, R3 = H; 4: R1 = CH3, R2 = H, R3 = 4-vinylphenyl; 5: R1 = CH3, R2 = F, R3 = H; 6: R1 = CH3, R2 = F, R3 = 4-vinylphenyl) have been synthesized and evaluated for ethylene polymerization using dried MAO(simplified as DMAO) as cocatalyst. An obvious catalytic heterogeneity of Cat 2(Complex 2/DMAO) towards ethylene polymerization was observed, which was illustrated by decreased activity, multimodal molecular weight distribution and partially improved particle morphology comparing with Cat 1. Moreover, Cat 3 exhibits "living" characteristics in the process under certain conditions(25 °C, less than 20 min). Otherwise, the moderate to high ethylene polymerization activity of ca. 105-106 g PE/(mol Ti·h) and high molecular weight(Mw = 105-106) of polyethylene can be obtained by changing the skeleton structure of these complexes.     

Phosphine/Benzocyclone-based Neutral Nickel Catalysts for Ethylene Polymerization and Copolymerization with Polar Monomers

The efficient copolymerization of olefin with polar monomers using nickel-based catalysts presents a longstanding challenge. In this contribution, three phosphine-benzocyclone ligands and corresponding neutral nickel catalysts(Ni1: Ar = Ph; Ni2: Ar = 2-(C6H5)C6H4; Ni3: Ar = 2-[2’,6’-(Me O)2-C6H3]C6H4) were prepared and applied for the ethylene polymerization and copolymerization with polar monomers without any cocatalyst. The bulky substituent groups in complexes Ni2 and Ni3 contributed to high ...     

Reductive dehalogenation of chloro(alkynyl)phosphines by octacarbonyldicobalt

Reductive dehalogenation of the (chloro)(phenylethynyl)phosphine (2,4,6-^tBu₃C₆H₂O)(PhCC)PCl, I, by Co₂(CO)₈, II, yields the neutral phosphenium ion complex [(R)(R′)]P=Co(CO)₃, III, (R = 2,4,6-^tBu₃C₆H₂O; R′ = (η²-C≡CPh)Co₂(CO)₆), which contains a trigonally planar coordinated phosphorus atom. When NaCo(CO)₄, V, is used instead of II a dinuclear complex, Co₂(CO)₆[μ²-P(R)(R′)]₂, VI, (R = 2,4,6-^tBu₃C₆H₂O; R′ = C≡CPh) is formed in which the phosphido ligands P(R)(R′), bridge in a μ₂ fashion two Co(CO)₃ units. The mechanism of formation of VI, involving a formal dimerization of two [(2,4,6-^tBu₃C₆H₂O)(PhC≡C)]P=Co(CO)₃ fragments, is discussed. However, (^tBu)(PhC≡C)PCl, VII, reacts with II, to yield the cluster compound VIII, containing the two μ₂-bridging units (^tBu)[(η²-C≡CPh)Co₂(CO)₅]P and (^tBu)(PhC≡C)P.

Compounds II and VI–VIII were identified from their analytical and spectroscopic (IR, ¹H-, ¹³C- and ³¹P-NMR) data. The molecular structure of the cluster compound VIII was determined by an X-ray diffraction study.     

Regioselective addition of chalcogenol to an η-propargyl/allenyl complex via formation of the carbon-chalcogen bond leading to new chalcogenoxyallyl species

Regioselective addition of chalcogenol to an ν³-propargyl complex Pt(PPh₃)₂(η³-C₃H₃)](BF₄) (2) via the formation of the C---O, C---S, or C---Se bond generates new cationic chalcogenoxyallyl species {Pt(PPh₃)₂[η³CH₂C(ER)CH₂]}(BF₄) (E = O, R = Me 4(a), Et (4b, ⁱPr (4c), ¹Bu (4d), Ph (4e); E=S, E=Et (5b), ^tBu (5d, Ph (5e); E=Se, R=Ph (6e )) respectively in good yields. Thiol and selenol react with complex 2 much faster than alcohol; and 2 reacts with p-(HO)C₆H₄(SH) to exclusively yield the thioxyallyl product {Pt(PPh₃)₂[η³-CH₂C(SC₆H₄OH)CH₂]}(BF₄) (5f). Among the alcoh and phenol, thereactivity follows the order MeOH > EtOH >, ⁱPrOH >, ^tBuOH > PhOH. A mechanism comprising a preceding coordination step is postulated. The X-ray structures of 4b, 4e, 5b, 5e and 6e are provided.     

Photochemical reactions of alkynyl iron (II) complexes with carbon disulfide. Insertion of CS2 into an iron-C(sp) bond

The novel alkynyldithiocarboxylate complexes [Fe(η⁵-C₅H₅)(S₂CCCR) (dppm-P)] (3a,b) and [Fe(η₅-C₅H₅)(S₂CCCR)(PPh₃)] (4a,b) were obtained through the insertion of CS₂ into the iron-akynyl bond in the complexes [Fe(η₅-C₅H₅)(CCR)(L)(L′] L, L′ = dppm R = Ph (1a), ^tBu(1b); L = (CO), L′ = (PPh₃) R = Ph (2a), ^tBu (2b). Variable-temperature ³¹P{¹H} NMR studies indicate the presence of two different isomers, [Fe(η⁵-C₅H₅)(η³-S,C,S′---S₂CCCR)(L)(L′)] and [Fe(η⁵-C₅H₅(η²-S,S′-S₂CCCR)(L)(L′)], which rapidly interconvert at room temperature. The synthesis of the precursor complex [Fe(η⁵-C₅H₅)(CC^tBu)(CO)(PPh₃)] is also described.     

Recent studies on metal and metalloid bis(trimethylsilyl)methyls and the transformation of the bis(trimethylsilyl)methyl into the azaallyl and β-diketinimato ligands

Recent results (post-1990) on the synthesis and structures of bis(trimethylsilyl)methyls M(CHR₂)_m (R = SiMe₃) of metals and metalloids M are described, including those of the crystalline lipophilic [Na(μ-CHR₂)]_∞, [Rb(μ-CHR₂)(PMDETA)]₂, K₄(CHR₂)₄(PMDETA)₂, [Mg(CHR₂)(μ-CHR₂)]_∞, P(CHR₂)₂ (gaseous) and P₂(CHR₂)₄, [Yb(CHR₂)₂(OEt₂)₂] and [{Yb(CR₃)(μ-OEt)(OEt₂)}₂]; earlier information on other M(CHR₂)_m complexes and some of their adducts is tabulated. Treatment of M(CHR₂) (M = Li or K) with four different nitriles gave the X-ray-characterized azaallyls or β-diketinimates , and (LL′ = N(R)C(^tBu)CHR, L′L′ = N(R)C(Ph)C(H)C(Ph)NR, LL″ = N(R)C(Ph)NC(H)C(Ph)CHR, R = SiMe₃ and Ar = C₆H₃Me₂-2,5). The two lithium reagents were convenient sources of other metal azaallyls or β-diketinimates, including those of K, Co(II), Zr(IV), Sn(IV), Yb(II), Hf(IV) and U(VI)/U(III). Complexes having one or more of the bulky ligands [LL′]⁻, [L′L′]⁻, [LL]⁻, [LL″]⁻, [L″L]⁻, [LL]⁻ and [{N(R)C(^tBu)CH}₂C₆H₄-2]²⁻ are described and characterized (LL = N(H)C(Ph)C(H)C(Ph)NH, L″L = N(R)C(^tBu)C(H)C(Ph)NR, LL = N(R)C(^tBu)CHPh). Among the features of interest are (i) the contrasting tetrahedral or square-planar geometry for and , respectively, and (ii) olefin-polymerization catalytic activity of some of the zirconium(IV) chlorides.     

柄型金属有机化合物(Ⅳ)——四甲基二硅桥连取代环戊二烯基钛和锆化合物的合成及催化乙烯聚合

四甲基二硅桥连取代环戊二烯基配体相继与丁基锂及MCl₄·2THF作用,生成四甲基二硅桥连取代环戊二烯基钛和锆化合物(Me₂SiSiMe₂)(C₅H₄R)(C₅H₄R')MCl₂[R=H,R'=t-Bu,M=Ti(1),Zr(2),Hf(3);R=H,R'=Me,M=Ti(4);R=R'=Me,M=Ti(5),Zr(6)].通过元素分析、MS和¹HNMR谱表征了化合物的分子结构,并通过X射线衍射分析测定了化合物1的晶体结构.研究了在甲基铝氧烷(MAO)的助催化下,化合物1-3和6对乙烯聚合的催化性能。     

柄型金属有机化合物(Ⅵ)——四甲基二硅氧桥连不对称茂金属化合物的合成、结构及催化乙烯聚合

四甲基二硅氧桥连不对称环戊二烯基及茚基配体C₅H₅Me₂SiOSiMe₂Cp′H相继与丁基锂及MCl₄·2THF作用,生成四甲基二硅氧桥连不对称茂金属化合物(Me₂SiOSiMe₂)(C₅H₄)(Cp′)MCl₂[Cp′=C₅H₃Bu^t,M=Ti(1),Zr(2);Cp′=C₉H₆,M=Ti(3),Zr(4)].通过元素分析、MS和¹H NMR谱表征了化合物的分子结构,并通过X射线衍射分析测定了化合物1的晶体结构.研究了在MAO(甲基铝氧烷)的助催化下,化合物1～4对乙烯聚合的催化性能.     

Alkyl-substituted cyclopentadienyl- and phospholyl-zirconium/MAO catalysts for propene and 1-hexene oligomerization

The directed oligomerization of propene and 1-hexene was carried out with a series of Cp′(C₅H₅)ZrCl₂ and Cp₂′ZrCl₂ pre-catalysts (Cp′=C₅HMe₄, C₄Me₄P, C₅Me₅, C₅H₄^tBu, C₅H₃-1,3-^tBu₂, C₅H₂-1,2,4-^tBu₃) together with (C₅H₅)₂ZrCl₂. Oligomers in the molar mass range 300–1500 g/mol for propene and 200–3000 g/mol for 1-hexene were synthesized at 50 °C. The majority of oligomer molecules contain a double-bond end group. Oligomer characterization was carried out by gel permeation chromatography (GPC), ¹H and ¹³C NMR. Vinylidene double bonds (from β-hydrogen elimination) are solely found for the tert-butyl-substituted zirconocenes and for most of the unsymmetrical methyl-substituted Cp′(C₅H₅)ZrCl₂ systems (except Cp′=phospholyl). With (C₄Me₄P)(C₅H₅)ZrCl₂ and with the symmetrical methyl-containing Cp₂′ZrCl₂ pre-catalysts, also vinyl end groups (from β-methyl elimination) are observed in the case of oligopropenes. The vinylidene/vinyl ratio depends on the ligand and the vinyl content increases from C₅HMe₄ (65/35) over C₄Me₄P (61/39) to C₅Me₅ (9/91). The phospholyl zirconocenes and (C₅HMe₄)₂ZrCl₂ also exhibit chain-transfer to aluminum thereby giving saturated oligomers.     

硅桥连双(三甲硅基环戊二烯基)钛化合物的合成及脱硅基反应

硅桥连双(三甲硅基环戊二烯基)双锂盐与TiCl₄·2THF反应,生成相应的钛化合物[E(C₅H₃SiMe₃)₂]TiCl₂[E=Me₂SiSiMe₂(3),Me₂SiOSiMe₂(5)],同时还分离到了脱一个三甲硅基的产物[E(C₅H₄)(C₅H₃SiMe₃)]TiCl₂[E=Me₂SiSiMe₂(4),Me₂SiOSiMe₂(6)].其中四甲基二硅氧桥连配体更容易发生这种脱硅基反应.通过元素分析、MS和¹HNMR谱表征了化合物3-6的分子结构.     

New organogold(I) complexes: Synthesis, structure, and dynamic behavior of the polynuclear organogold diphenylmethane and diphenylethane derivatives

Two organogold derivatives of diphenylmethane and diphenylethane, Ph₃PAu(o-C₆H₄)CH₂(C₆H₄-o)AuPPh₃ (1) and Ph₃PAu(o-C₆H₄)(CH₂)₂(C₆H₄-o)AuPPh₃ (2), have been synthesized by the reaction of ClAuPPh₃ with Li(o-C₆H₄)CH₂(C₆H₄-o)Li and Li(o-C₆H₄)(CH₂)₂(C₆H₄-o)Li respectively. The interaction of 1 with dppe results in the replacement of the two PPh₃ groups to give a macrocyclic compound (3) that includes an Au Au bond. Compounds 1 and 2 react with one or two equivalents of [Ph₃PAu]BF₄ to form new types of cationic complex [CH₂(C₆H₄-o)₂(AuPPh₃)₃]BF₄ (4), [CH₂(C₆H₄-o)₂(AuPPh₃)₄](BF₄)₂ (5), and [(CH₂)₂(C₆H₄-o)₂(AuPPh₃)₄](BF₄)₂ (6). Complexes 1–6 have been characterized by X-ray diffraction studies, FAB MS, and IR as well as by ¹H and ³¹P NMR spectroscopy. A complicated system of Au H-C agostic interactions, involving the bridging alkyl groups (—CH₂— and CH₂-CH₂—) of diphenylmethane and diphenylethane ligands, has been found to occur in complexes 1–3 and 6.     

Synthese und reaktivität von dienylmetall-verbindungen : XXVII. Ein einfacher weg zur synthese von cyclopentadienylcobalt(III)-dikationen

CpCo(CO)₂ is oxidised by [Cp₂Fe]BF₄ (Cp = C₅H₅) in the presence of neutral ligands L to give the dications [CpCoL₃]²⁺ (L = SMe₂, S(n-C₄H₉)₂, PMe₃, C₅H₅N, MeCN; Me = CH₃). In [CpCo(SMe₂)₃]²⁺, sulfane ligands are substituted by neutral ligands L, L---L and L---L---L, to give the complexes [CpCoL₃]²⁺ (L = SeMe₂, TeMe₂, PMe₃, P(OMe)₃, AsMe₃, SbMe₃, t-C₄H₉NC, C₅H₅N, MeCN), [Cp-Co(L---L)SMe₂]²⁺ (L---L = R₂P(CH₂)_nPR₂, n = 1, 2, R = C₆H₅; bipyridine, o-phenanthroline, neocuproin) and [CpCo(L---L---L)]²⁺ (L---L---L = RP(CH₂CH₂PR₂)₂, R = C₆H₅). The dications react with iodide resulting in the monocations [CpCoL₂I]⁺ and [CpCo(L---L)I]⁺. Azacobaltocinium cations [CpCo(C₄R₂H₂N)]⁺ (R = H, CH₃) are obtained by reaction of [CpCo(SMe₂)₃]²⁺ with metal pyrrolides.