二(β-羟亚胺)二氯化钛配合物的合成及催化乙烯聚合

报道了3个β-羟亚胺配体(2,6-^emPr₂C₆H₃)N＝C(Ph)CH₂CH(Ph)OH(1a), (2,6-^emPr₂C₆H₃)N＝C·(Ph)CH₂C(Ph)₂OH(1b)和(2,6-^emPr₂C₆H₃)N＝C(Ph)CH₂C(C₁₂H₈)OH(1c)及其二(β-羟亚胺)二氯化钛配合物[(2,6-^emPr₂C₆H₃)N＝C(Ph)CH₂CH(Ph)O]₂TiCl₂(2a), [(2,6-^emPr₂C₆H₃)N＝C(Ph)CH₂C(Ph)₂O]₂·TiCl₂(2b)和[(2,6-^emPr₂C₆H₃)N＝C(Ph)CH₂C(C₁₂H₈)O]₂TiCl₂(2c)的合成, 并对其结构进行了表征. 在助催化剂甲基铝氧烷(MAO)作用下, 以化合物2b为主催化剂, 研究了Al/Ti摩尔比、 反应时间、 温度和聚合压力等对乙烯聚合的影响, 发现该催化体系在较宽的反应条件下均可得到很高分子量的聚乙烯, 熔点均在140℃左右. 以化合物2a~2c为主催化剂对乙烯进行催化聚合, 发现在β碳位上取代基的立体位阻对催化剂活性有很大影响. 当化合物2b上引入2个苯基取代基时, 催化剂显示出最佳催化活性.     

Bulky iminophosphine-based nickel and palladium catalysts bearing 2,6-dibenzhydryl groups for ethylene oligo-/polymerization

A series of 2,6-dibenzhydryl substituted bulky Ni and Pd complexes containing P,N-chelating ligands, {[2,6-(Ph₂CH)₂-4-R-C₆H₂-N=CH-C₆H₄-2-PPh₂]MX₂; MX₂ =NiBr₂; R = Me ( Ni1 ); R = F ( Ni2 ); MX₂ =PdCl₂, R = Me ( Pd1 )}, have been prepared and used as catalyst precursors for ethylene oligo-/polymerization. Compared to the corresponding 2,6-diisopropyl Ni catalyst, these bulky Ni precatalysts activated by Et₂AlCl exhibited excellent catalytic performance toward ethylene polymerization with activity of up to 1.90 × 10⁵ g PE (mol Ni)⁻¹ h⁻¹, and result in semicrystalline PEs with high molecular weight. The catalytic performance of these bulky P,N-type complexes was significantly improved by introducing two ortho-dibenzhydryl on the N-aryl substituents. However, the formation of C₁₀–C₂₄ oligomers were generated using their palladium catalysts through ethylene oligomerization at high temperatures.     

Synthesis and characterisation of benzyl phosphino-thioether and -thiolato Pd(II) complexes and their applications in Suzuki coupling reactions

The synthesis of the benzyl phosphinothioether derivatives Ph(2)PCH(2)CH(Et)SR and their corresponding palladium complexes are reported, where R = CH(2)Ph, R = CH(2)-3,5-Me-C(6)H(3) and R = 1-CH(2)C(10)H(7)(5). Crystallographic data obtained for the complexes Pd(3)Cl(2) and Pd(4)Cl(2) show intra- and inter-molecular pi-pi interactions between the aromatic rings on the P and S substituents, and NOE experiments for Pd(4)Cl(2) show that these interactions persist in solution. The performance of the phosphinothioether palladium complexes in aryl-aryl cross-coupling reactions is compared with that of the corresponding complex of the parent phosphinothiolato ligand Ph(2)PCH(2)CH(Et)S(-)(1). High turnover numbers up to 2000000 are reported for the coupling of bromobenzene, using the palladium dimer [Pd(1)I](2) as the catalyst precursor. Kinetic studies show a linear dependence of the reaction on catalyst loading. The effect of other variables on the cross-coupling reaction, such as temperature, solvent and base, is also reported.     

Synthesis and structures of nickel and palladium salicylaldiminato 1,3,5-triaza-7-phosphaadamantane (PTA) complexes

The synthesis of nickel(II) and palladium(II) salicylaldiminato complexes incorporating the water-soluble phosphine 1,3,5-triaza-7-phosphaadamantane(PTA) has been achieved employing two preparative routes. Reaction of the original ethylene polymerization catalyst developed by Grubbs and co-workers (Organometallics 1998, 17, 3149), (salicylaldiminato)Ni(Ph)PPh(3), with PTA using a homogeneous methanol/toluene solvent system resulted in the formation of the PTA analogues in good yields. Alternatively, complexes of this type may be synthesized via a direct approach utilizing (tmeda)M(CH(3))(2) (M = Ni, Pd), the corresponding salicylaldimine, and PTA. Yields by this method were generally near quantitative. The complexes were characterized in solution by (1)H/(13)C/(31)P NMR spectroscopy and in the solid-state by X-ray crystallography. All derivatives exhibited square-planar geometry with the bulky isopropyl groups on the aniline being perpendicular to the plane formed by the metal center and its four ligands. Such orientation of these sterically encumbering groups is responsible for polymer chain growth during olefin polymerization in favor of chain termination via beta-hydride elimination. Polymerization reactions were attempted using the nickel-PTA complexes in a biphasic toluene/water mixture in an effort to initiate ethylene polymerization by trapping the dissociated phosphine ligand in the water layer, thereby eliminating the need for a phosphine scavenger. Unfortunately, because of the strong binding ability of the small, donating phosphine(PTA) as compared to PPh(3), phosphine dissociation did not occur at a temperature where the complexes are thermally stable.     

Catalytic Effect of Cobalt and Iron Complexes Incorporating Bis(2-aldiminoethyl)amine Ligands on Ethylene Oligomerization

IntroductionThe finding of a new promising family ofFe( ) - and Co( ) - based bis( imino) pyridyl cata-lysts for ethylene polymerization and oligomeriza-tion,discovered by Brookhart,Gibson andcoworkers[1— 3 ] ,has intrigued us into researchingthe preparation,the structure and the chemistry ofiron and cobalt complexes incorporating N,N ,N -tridentate ligands.The spectacular enhancement ofthe reactivity of iron and cobalt complexes towardsZiegler- Natta olefin polymerization has been re-po…     

Dinuclear nickel and palladium complexes with bridging 2,5-diamino-1,4-benzoquinonediimines: synthesis, structures, and catalytic oligomerization of ethylene

Dinuclear, divalent acetylacetonato (acac) complexes of the type [M(acac){mu-C6H2(--NR)4}M(acac)] (M = Ni, Pd) have been prepared by the reaction of the corresponding bis(acac) metal precursor with 2,5-diamino-1,4-benzoquinonediimines C6H2(NHR)2(=NR)2 (4a, R = CH2-t-Bu; 4b, R = CH2Ph; 4c, R = Ph), which are metalated and become bridging ligands, also like in the complex [(C8H11)Pt{mu-C6H2(--NCH2-t-Bu)4}Pt(C8H11)] (6) obtained by the reaction of 4a with [PtCl2(COD)]. The complexes were fully characterized, including by X-ray diffraction for [Ni(acac){mu-C6H2(--NCH2Ph)4}Ni(acac)] (9b) and [Pd(acac){mu-C6H2(--NCH2-t-Bu)4}Pd(acac)] (10a). The coordination geometry around the metal ions is square-planar, and a complete electronic delocalization of the quinonoid pi system occurs between the metal centers over the two N--C--C--C--N halves of the ligand. The nature of the N substituent explains the differences between the supramolecular stacking arrangements found for [Ni(acac){mu-C6H2(--NR)4}Ni(acac)] (9a; R = CH2-t-Bu; 9b, R = CH2Ph). The Ni complexes were evaluated as catalyst precursors for ethylene oligomerization in the presence of AlEtCl(2) or MAO as the cocatalyst, in particular in order to study possible cooperative effects resulting from electronic communication between the metal centers and to examine the influence of the N substituent on the activity and selectivity. These catalysts afforded mostly ethylene dimers and trimers.     

Chelating N-pyrrolylphosphino-N'-arylaldimine ligands: synthesis, ligand behaviour and applications in catalysis

Two families of variously-substituted N-pyrrolylphosphino-N'-arylaldimine ligands, 2-(aryl-N=CH)C4H3N-PR2 {R=Ph; R=Pri2N}, have been prepared from the corresponding pyrrolylaldimines . The donor characteristics/basicity of P-N-chelating and have been assessed using a combination of 31P{1H} NMR and IR spectroscopies through study of the magnitudes of 1JSeP for the phosphorus(V) selenides and , and measurement of nu(CO) for the complexes [RhCl(CO)(-kappa2-P,N)], respectively. The synthesis of the palladium(II) complexes [PdCl2(-kappa2-P,N)] was readily achieved from reaction of or with [PdCl2(MeCN)2] in CH2Cl2. X-Ray crystallographic studies of and confirm the chelating nature of the P-N ligands, which adopt a distorted 'envelope' conformation, and highlight the potentially significant steric demands of these metal scaffolds. Reaction of equimolar quantities of with [NiBr2(DME)] in MeCN afforded [NiBr2(-kappa2-P,N)], while the same reaction undertaken in CH2Cl2 with gave rise to the homoleptic bis(pyrrolatoimine) derivative [Ni{2-(mes-N=CH)C4H3N}2] in 45% yield, following P-N bond cleavage. Complex was characterised in the solid-state by X-ray crystallography. No identifiable metal-containing complexes could be obtained on reaction of with a variety of sources of Ni(II). The palladium dichloride complexes and proved inactive in combination with MAO or EtAlCl2 for ethylene polymerisation, and with methanesulfonic acid for CO/ethylene co-polymerisation. Contrastingly, the nickel complexes in combination with 4.5 eq. EtAlCl2 catalysed the formation of butenes and hexenes with moderate activity from ethylene at 1 bar.     

Binuclear half-metallocene chromium(III) complexes mediated ethylene polymerization with alkylaluminium as cocatalyst

Binuclear half-metallocene chromium complexes {Cp*[3-(CH==NR)-2-O-C(10)H(5)]CrCl}(2) [Cp* = C(5)Me(5); R = (i)Pr (1), Ph (2), 2,6-(i)Pr(2)C(6)H(3) (3)] based on 1,1'-binaphthyl ligands, as well as their mononuclear analogues Cp*[3-(CH==NR)-2'-R'-2-O-C(20)H(11)]CrCl [R = (i)Pr, R' = (n)BuO (4), R = Ph, R' = (n)BuO (5), R = 2,6-(i)Pr(2)C(6)H(3), R' = (n)BuO (6), R = (i)Pr, R' = H (7)], were synthesized and characterized by mass spectrometry, elemental analysis, magnetic measurement, and UV-vis spectroscopy. The molecular structures of complexes 1, 3, 5 and 6 were further confirmed by single-crystal X-ray crystallographic analysis. When activated with a small amount of AlMe(3), these binuclear complexes exhibited higher activities in catalyzing ethylene polymerization in comparison with their mononuclear analogues, affording high molecular weight polymers with unimodal molecular weight distributions. The highest activity up to 2.87 × 10(6) g PE (mol Cr)(-1) h(-1) was achieved in the catalyst system of complex 3 bearing a bulky 2,6-(i)Pr(2)C(6)H(3) group on the imine nitrogen atom in the presence of 25 equiv. AlMe(3) as activator at 20 °C. (13)C NMR analysis indicates the resultant polymers are linear and no evidence on branch was found.     

Oligomerization and regioselective hydrosilylation of styrenes catalyzed by cationic allyl nickel complexes bearing allylphosphine ligands

The complexes [Ni(eta(3)-CH(2)CHCH(2))Br(kappa(1)P-PR(2)CH(2)CH=CH(2))] (R = Ph 1, (i)Pr2 ) and [Ni(eta(3)-CH(2)C(R')CH(2))(kappa(1)P-PR(2)CH(2)CH=CH(2))(2)][BAr'(4)] (R' = H, R = Ph 4a, R = (i)Pr 4b; R' = CH(3), R = Ph 5a, R = (i)Pr 5b; Ar' = 3,5-C(6)H(3)(CF(3))(2)) have been prepared and characterized. The X-ray crystal structures of 1, 2 and 5b have been determined. 4a-b and 5a-b are catalyst precursors for the oligomerization of RC(6)H(4)CH=CH(2) to oligostyrene (R = H) or oligo(4-methylstyrene) (R = CH(3)) respectively, without the need of a co-catalyst such as methylalumoxane. The catalytic activities range from moderate to high. The oligomerization reactions are carried out in the temperature interval 25-40 degrees C in 1,2-dichloroethane, using an olefin/catalyst ratio equal to 200, yielding oligostyrenes with a high isotactic fraction content P(m), with M(n) in the range 700-1900 Dalton, and polydispersities between 1.22 and 1.64. The cationic complexes 4a-b and 5a-b are also effective catalyst precursors for the hydrosilylation reactions of styrene or 4-methylstyrene with PhSiH(3) in 1,2-dichloroethane at 40 degrees C using an olefin/catalyst ratio equal to 100, leading selectively to RC(6)H(4)CH(SiH(2)Ph)CH(3) (R = H, CH(3)) in 50-79% yield.     

Methoxycarbonylation of olefins catalyzed by palladium complexes bearing P,N-donor ligands

The methoxycarbonylation of alkenes catalyzed by palladium(II) complexes with P,N-donor ligands, 2-(diphenylphosphinoamino)pyridine (Ph2PNHpy), 2-[(diphenylphosphino)methyl]pyridine (Ph2PCH2py), and 2-(diphenylphosphino)quinoline (Ph2Pqn) has been investigated. The results show that the complex [PdCl(PPh3)(Ph2PNHpy)]Cl or an equimolar mixture of [PdCl2(Ph2PNHpy)] and PPh3, in the presence of p-toluensulfonic acid (TsOH), is an efficient catalyst for this reaction. This catalytic system promotes the conversion of styrene into methyl 2-phenylpropanoate and methyl 3-phenylpropanoate with nearly complete chemoselectivity, 98% regioselectivity in the branched isomer, and high turnover frequency, even at alkene/Pd molar ratios of 1000. Best results were obtained in toluene-MeOH (3 : 1) solvent. The Pd/Ph2PNHpy catalyst is also efficient in the methoxycarbonylation of cyclohexene and 1-hexene, although with lower rates than with styrene. Related palladium complexes [PdCl(PPh3)L]Cl (L = Ph2PCH2py and Ph2Pqn) show lower activity in the methoxycarbonylation of styrene than that of the 2-(diphenylphosphinoamino)pyridine ligand. Replacement of the last ligand by (diphenylphosphino)phenylamine (Ph2PNHPh) or 2-(diphenylphosphinoaminomethyl)pyridine (Ph2PNMepy) also reduces significantly the activity of the catalyst, indicating that both the presence of the pyridine fragment as well as the NH group, are required to achieve a high performing catalyst. Isotopic labeling experiments using MeOD are consistent with a hydride mechanism for the [PdCl(PPh3)(Ph2PNHpy)]Cl catalyst.     

Yttrium and lanthanide complexes with various P,N ligands in the coordination sphere: synthesis, structure, and polymerization studies

Yttrium and lanthanide complexes with different P,N ligands in the coordination sphere have been synthesized. First the chloride complexes [{CH(PPh2NSiMe3)2}Ln{(Ph2P)2N}Cl] (Ln = Y (1 a), La (1 b), Nd (1 c), Yb (1 d)) having the bulky [CH(PPh2NSiMe3)2]- and the flexible [(Ph2P)2N]- ligands in the same molecule were prepared by three different synthetic pathways. Compounds 1 a-d can be obtained by reaction of [{[CH(PPh2NSiMe3)2]LnCl2}2] with [K(thf)nN(PPh2)2] (n = 1.25, 1.5) or by treatment of [{(Ph2P)2N}LnCl2(thf)3] with K[CH(PPh2NSiMe3)2]. Furthermore, a one-pot reaction of K[CH(PPh2NSiMe3)2] with LnCl3 and [K(thf)nN(PPh2)2] leads to the same products. Single-crystal X-ray structures of 1 a-d show that the conformation of the six-membered metallacycle (N1-P1-C1-P2-N2-Ln) which is formed by chelation of the [CH(PPh2NSiMe3)2]- ligand to the lanthanide atom is influenced by the ionic radius of the central metal atom. In solution dynamic behavior of the [(Ph2P)2N]- ligand is observed, which is caused by rapid exchange of the two different phosphorus atoms. Further reaction of 1 b with KNPh2 resulted in [{(Me3SiNPPh2)2CH}La{N(PPh2)2}(NPh2)] (2). Compounds 1 a-d and 2 are active in the ring-opening polymerization of epsilon-caprolactone and the polymerization of methyl methacrylate. In some cases high molecular weight polymers with good conversions and narrow polydispersities were obtained. In both polymerizations the catalytic activity depends on the ionic radius of the metal center.     

Asymmetric Cationic [P,O] Type Palladium Complexes in Olefin Homopolymerization and Copolymerization

Metal‐catalyzed ethylene homopolymerization and ethylene‐polar monomer copolymerization to produce new kinds of polyolefins with novel microstructures are of great interest. So far, there are some disadvantages for traditional transition metal catalyst systems. Therefore, it is critical to develop new catalysts or alternative strategies. In recent years, some cationic [P, O] palladium complexes have been demonstrated with the abilities to obtain oligomers and the high molecular weight polymers. Most importantly, these complexes showed high activity and generated polymers with specific microstructures when used for copolymerization of ethylene with industrially relevant polar monomers. This review summarizes several types of high performance cationic [P, O] palladium catalysts in ethylene oligomerization, ethylene homopolymerization and the copolymerization of ethylene with polar monomers. Specially, the regulation of steric and electronic effects at specific sites of the metal complexes was focused.     

Catalytic applications of keto-stabilised phosphorus ylides based on a macrocyclic scaffold: calixarenes with one or two pendant Ni(P,O)-subunits as ethylene oligomerisation and polymerisation catalysts

Four calix[4]arenes containing either one or two ylidic -C(O)CH=PPh3 moieties anchored at p-phenolic carbon atoms were prepared starting from cone-25,27-dipropoxycalix[4]arene (1): 1,3-alternate-5,17-bis(2-triphenylphosphoranylideneacetyl)-25,26,27,28-tetrapropoxycalix[4]arene (12), 1,3-alternate-5-(2-triphenylphosphoranylideneacetyl)-25,26,27,28-tetrapropoxycalix[4]arene (13), cone-5-(2-triphenylphosphoranylideneacetyl)-25,27-dihydroxy-26,28-dipropoxycalix[4]arene (14), cone-5,17-bis(2-triphenylphosphoranylideneacetyl)-25,27-dihydroxy-26,28-dipropoxycalix[4]arene (15). All the ylides were shown to be suitable for the preparation of SHOP-type complexes, i.e. of molecules containing [NiPh{Ph2PCH=C(O)R}(PPh3)] subunits (R = calixarene fragment). The monometallic complexes, namely those obtained from the monophosphorus ylides 13 and 14, proved to be efficient ethylene oligomerisation or polymerisation catalysts. At 80 degrees C, they displayed significantly better activities than the prototype [NiPh{Ph(2)PCH=C(O)Ph}(PPh3)], hence reflecting the beneficial role of the bulky calixarene substituent. The systems derived from the two ylides 12 and 15, both containing two convergent ylidic moieties, resulted in lower activities, the proximity of the two catalytic centres facilitating an intramolecular deactivation pathway during the period of catalyst activation. For the first time, the solid-state structure of a complex containing two "NiPh(P,O)(PPh3)" units as well as that of a SHOP-type complex having two linked phosphorus units were determined.     

Mono- and dinuclear five-coordinate cyclometalated palladium(II) compounds

Reaction of cyclometalated halide-bridged Pd(II) complexes 1-4 with the tertiary triphosphine ligand (Ph2PCH2CH2)2PPh (triphos) yielded complexes [((Ph2PCH2CH2)2PPh-P,P,P)Pd(N(Cy)=(H)C)C6H2(C(H)=N(Cy))Pd((Ph2PCH2CH2)2PPh-P,P,P)][ClO4]2 5, [Pd(C6H4-N=NC6H5)((Ph2PCH2CH2)2PPh-P,P,P)][ClO4] 6, and [Pd(R-C6H3C(H)=NCy)((Ph2PCH2CH2)2PPh-P,P,P)][ClO4] (7; R = 4-CHO, 8; 3-CHO). Spectroscopic and analytic data suggest five-coordination on the palladium atom, which, for complexes 5, 6, and 7, was confirmed by X-ray crystallography. The geometry around palladium may be view as a distorted trigonal bipyramid, with the palladium, nitrogen, and terminal phosphorus atoms in the equatorial plane. Compound 5 is the first doubly cyclometalated palladium(II) compound with two pentacoordinated metal centers. The structure of 6 comprises two discrete cations with slightly different geometries, showing the importance of crystal packing forces in order to determine the coordination arrangement.     

Strategies for the anchoring of metal complexes, clusters, and colloids inside nanoporous alumina membranes

Two complementary strategies are presented for the anchoring of molecular palladium complexes, of cobalt or platinum clusters or of gold colloids inside the nanopores of alumina membranes. The first consists in the one step condensation of an alkoxysilyl functional group carried by the metal complex with the hydroxy groups covering the surface of the membrane pores. Thus, using the short-bite alkoxysilyl-functionalized diphosphane ligands (Ph2P)2N(CH2)3Si(OMe)3 (1) and (Ph2P)2N(CH2)4SiMe2(OMe)] (2) derived from (Ph2P)2NH (dppa) (dppa bis(diphenylphosphanyl)amine), the palladium complexes [Pd(dmba)(kappa2-P,P-(Ph2P)2N(CH2)3Si(OMe)3)] Cl (3) and [Pd(dmba)[kappa2-P,P-(Ph2P)2N(CH2)4SiMe2(OMe)]]Cl (4) (dmba-H = dimethylbenzylamine). respectively, were tethered to the pore walls. After controlled thermal treatment. confined and highly dispersed palladium nanoparticles were formed and characterized by transmission electron microscopy (TEM). This method could not be applied to the cobalt cluster [Co4(CO)8(mu-dppa)[mu-P,P-(Ph2P)2N(CH2)4SiMe2(OMe)]] (7) owing to its too limited solubility. However, its anchoring was achieved by using the second method which consisted of first derivatizing the pore walls with 1 or 2. The covalent attachment of the diphosphane ligands provides a molecular anchor that allows subsequent reaction with the cluster [Co4(CO)10(mu-dppa)] 6 to generate anchored 7 and this step was monitored by UV/Vis spectroscopy. In addition, the presence of carbonyl ligands in the cluster provides for the first time a very sensitive spectroscopic probe in the IR region which confirms both cluster incorporation and the retaining of its molecular nature inside the membrane. The presence of the bridging dppa ligand in 6 provides additional stabilization and accounts for the selectivity of the procedure. Using this method, platinum clusters (diameter ca. 2 nm) and gold colloids (diameter ca. 13 nm) were immobilized after passing their solution through the functionalized membrane pores. The resulting membranes were characterized by TEM which demonstrated the efficiency of the complexation and showed the high dispersion of the metal loading. The successful application of these methods has demonstrated that nanoporous alumina membranes are not only unique supports to incorporate metal complexes, clusters, or colloids but can also be regarded as functional matrices or microreactors, thus opening new fields for applications.     

Synthesis of beta-P,N aminophosphines and coordination chemistry to Pd(II). X-ray structures of [PdCl2(Ph2PCH(Ph)NHPh-kappaP,kappaN)] and PdCl(eta3-C3H5)(Ph2PCH2CH(Ph)NHPh-kappaP)

The reaction of the C=N bond in PhCH=NPh with the carbanionic species Ph2PCH2-, leading to the N-phenyl beta-aminophosphine Ph2PCH2CH(Ph)NHPh, L1, is described. This molecule reacts with different organic electrophiles to afford related compounds Ph2PCH2CH(Ph)NPhX (X = SiMe3, L2; COPh, L4), [Ph2MePCH2CH(Ph)NHPh]+(I-), L3, and [Ph2PCH2CH(Ph)N(Ph)CO]2, L5, containing two amido and two phosphino functions. The coordination properties of L1, L2, and L4 have been studied in palladium chemistry. The X-ray structure of [PdCl2(Ph2PCH2CH(Ph)NHPh-kappaP,kappaN)] shows the bidentate coordination mode for the L1 ligand with equatorial C(Ph)-N(Ph) phenyl groups. [PdCl2(Ph2PCH2CH(Ph)NHPh-kappaP,kappaN)] crystallizes at 298 K in the space group P2(1)/n with cell parameters a = 10.689(2) A, b = 21.345(3) A, c = 12.282(2) A, beta = 90.294(12) degrees, Z = 4, D(calcd) = 1.526. The reaction between 2 equiv of L1 and [PdCl(eta3-C3H5)]2 affords the [PdCl(eta3-C3H5)(Ph2PCH2CH(Ph)NHPh-kappaP)] complex in which an unexpected N-H.Cl intramolecular interaction has been observed by an X-ray diffraction analysis. [PdCl(eta3-C3H5)(Ph2PCH2CH(Ph)NHPh-kappaP)] crystallizes at 298 K in the monoclinic space group Cc with cell parameters a = 10.912(1) A, b = 17.194(2) A, c = 14.169(2) A, beta = 100.651(9) degrees, Z = 4, D(calcd) = 1.435. Neutral and cationic alkyl or allyl palladium chloride complexes containing L1 are also reported as well as a neutral allyl palladium chloride complex containing L4. Variable-temperature 31P[1H] NMR studies on the allyl complexes show that the eta3/eta1 allyl interconversion is enhanced by a positive charge and also by a N-H.Cl intramolecular interaction.     

Polymerization of styrene by Novel Ni(Ⅱ)- and Pd(Ⅱ)-based complexes

The catalytic activities of nine neutral nickel and palladium a-acetylide complexes [M=(C=CR)2(PR'3)2)M=Ni,Pd; R=Ph,CH2OH,CH2OOCH3,CH2OOCPh,CH2OOCPhOH-o; R'=Ph,Bu] are compared.Among them,Ni(Cs=CPh)2-(PBuj)2 shows the highest catalytic activity and gives the polystyrene with high molecular weight(Mw=188800)and a syndio-rich microstructure.The catalytic behavior of transition metal acetylides is related to metal,phosphine,and alkynyl ligands bonded to the metal atoms.     

Mechanistic studies of nickel(II) alkyl agostic cations and alkyl ethylene complexes: investigations of chain propagation and isomerization in (alpha-diimine)Ni(II)-catalyzed ethylene polymerization

The synthesis of a series of (alpha-diimine)NiR(2) (R = Et, (n)Pr) complexes via Grignard alkylation of the corresponding (alpha-diimine)NiBr(2) precursors is presented. Protonation of these species by the oxonium acid [H(OEt(2))(2)](+)[BAr'(4)](-) at low temperatures yields cationic Ni(II) beta-agostic alkyl complexes which model relevant intermediates present in nickel-catalyzed olefin polymerization reactions. The highly dynamic nature of these agostic alkyl cations is quantitatively addressed using NMR line broadening techniques. Trapping of these complexes with ethylene provides cationic Ni alkyl ethylene species, which are used to determine rates of ethylene insertion into primary and secondary carbon centers. The Ni agostic alkyl cations are also trapped by CH(3)CN and Me(2)S to yield Ni(R)(L)(+) (L = CH(3)CN, Me(2)S) complexes, and the dynamic behavior of these species in the presence of varied [L] is discussed. The kinetic data obtained from these experiments are used to present an overall picture of the ethylene polymerization mechanism for (alpha-diimine)Ni catalysts, including effects of reaction temperature and ethylene pressure on catalyst activity, polyethylene branching, and polymer architecture. Detailed comparisons of these systems to the previously presented analogous palladium catalysts are made.     

Bridged bis-pyridinylimino dinickel(II) complexes: Syntheses, characterization, ethylene oligomerization and polymerization

A series of bridged bis(pyridinylimino) ligands were efficiently synthesized through the condensation reaction of 4,4′-methylene-bis(2,6-disubstituted aniline) with 2-pyridinecarboxaldehyde or 2-benzoylpyridine. They reacted with (DME)NiBr₂ to form dinuclear Ni(II) complexes. All resultant compounds were characterized by elemental analysis, IR spectra as well as the single-crystal X-ray diffraction to confirm the structures of ligands and complexes. Activated with methylaluminoxane (MAO), these nickel complexes showed considerably good activities for ethylene oligomerization and polymerization. Their catalytic activities and the properties of PEs obtained were depended on the arched environment of ligand and reaction conditions.     

钯催化CO/乙烯共聚配体和阴离子效应

由ＣＯ与乙烯共聚制备的聚酮高分子,属新型功能高分子材料,由于其具有良好的光降解性,避免了传统非降解材料对生态环境造成的白色污染,同时由价廉的ＣＯ代替５０ %的乙烯直接制备高附加值的聚酮高分子,节约了石油资源,合理精细的利用了煤资源和其它化学过程中副产的ＣＯ,符合近代化工对环保和资源的要求,因而在近二十年来得到了快速发展,目前Ｓｈｅｌｌ公司已有万吨级的工业化装置,并有少量产品上市．制备聚酮的关键技术是高效钯 (Ⅱ )催化剂,该催化剂一般以三元组合物的形式加入到聚合釜中［１］,(１)醋酸钯,(２)双膦配体 (Ｌ…