Synthesis,reactivity and electrochemical properties of substituted cyclopentadienyl cobalt (Ⅲ) complexes

Cyclopentadienyl cobalt complexes (n5-C5H4R)CoLI2 [L = CO,R=-COOCH2CH=CH2 (3); L=PPh3,R=-COOCH2-CH=CH2 (6); L= P(p-C6H4CH3)3,R=-COOC(CH3) = CH2 (7),-COOCH2C6H5(8),-COOCH2CH = CH2 (9)] were prepared and characterized by elemental analyses,1H NMR,IR and UV-vis spectra.The reaction of complexes (n5-C5H4R)CoLI2[L=CO,R=-COOC(CH3)=CH2 (1) ,-COOCH2C6H5(2):L=PPh3,R =-COOC(CH3)=CH2 (4),-COOCH2C6H5(5)] with Na-Hg resulted in the formation of their corresponding substituted cobaltocene (n5-C5H4R)2Co [R= -COOC(CH3) = CH2 (10),-COOCH2C6H5 (11) ].The electrochemical properties of these complexes 1-11 were studied by cyclic voltammetry.It was found that as the ligand (L) of the cobalt (Ⅲ) complexes changing from CO to PPh3 and P(p-tolyl)3,their oxidation potentials increased gradually.The cyclic voltammetry of α,α'-substituted cobaltocene showed reversible oxidation of one electron pro-     

Synthesis,structure and catalytic activity of complexes [Ln(EDBP)_2(DME)Na(DME)_3](Ln=Er,Yb,Sm) for ring-opening polymerization of ε-caprolactone

Discrete ion-pair complexes [Ln(EDBP)2(DME)Na(DME)3] [Ln=Er (1), Yb (2), Sm (3)] have been synthesized by the reaction between sodium salt of 2,2'-ethylidene-bis(4,6-di-tert-butylphenol)(EDBPH2) and Ln(BH4)3·3THF (Ln=Er, Yb, Sm) followed by centrifugation and recrystalization. The complexes were characterized by elemental analysis and FT-IR, and the bonding model of these compounds was confirmed by X-ray single crystal diffraction for complex 1. It was found that four O atoms in two biphenol ligands as well...     

n-Octyloxyallene homopolymerization and random copolymerization with styrene using catalyst system composed of lanthanide Schiff-base complexes and Al(i-Bu)3

The catalyst system composed of lanthanide Schiff-base complexes with [3,5-tBu2 -2-(O)C6H2 CH=NC6H5]3 Ln(THF)(Ln(Salen)3 , Ln = Sc, Y, La, Nd, Sm, Gd, Yb) and triisobutyl aluminum shows high activity for n-octyloxyallene (A) homopolymerization with narrow molecular weight distribution (MWD). The influences of reaction conditions on polymerization behavior are investigated, and poly(n-octyloxyallene) has a weight average molecular weight (M w ) of 20.6 × 10 3 with MWD of 1.39 and 100% yield is obtained under the optimum conditions: [Al]/[Y] = 50 mol/mol, [A]/[Y] = 100 mol/mol, with polymerization at 80 ℃ for 16 h in bulk. The kinetic studies of n-octyloxyallene homopolymerization indicate that the polymerization rate is first-order with respect to the monomer concentration and shows some controlled polymerization characteristics. Random copolymer of n-octyloxyallene with styrene is obtained by using the same binary catalyst system; the reactivity ratios of the comonomer determined by Kelen Tüd s method are r A = 1.20 and r St = 0.35, respectively, the ratio of each segment and M w of the resulting copolymer could be controlled by varying the feed ratio of each monomer. Determined by differential scanning calorimetry, the copolymers obtained show only one glass transition temperature, which increases gradually with the increase of styrene content in the copolymer.     

Synthesis, Structure and Catalytic Activity Comparison of Tris- and Tetracoordinated Lanthanide Amides

Tetracoordinated lanthanide amides [(MeaSi)2N]3Ln (μ-C1)Li(THF)3 (Ln=La (1), Pr (2)) were synthesized by the reaction of anhydrous lanthanide(Ⅲ) chlorides LnCl3 (Ln=La, Pr) with 3 equiv, of lithium bis(trimethylsilyl)amide (Me3Si)2NLi in THF, followed by recrystallization from toluene. Sublimation of 1 and 2 afforded the triscoordinate lanthanide amides [(Me3Si)2N]3Ln (Ln=La, Pr). The crystal structure of 2 was determined by X-ray diffraction analysis. The catalytic activity studies show that the tetracoordinate amides can be used as single-component MMA (methyl methacrylate) polymerization catalysts, while the triscoordinate amides showed poor activity on MMA polymerization under the same conditions.     

Synthesis and characterization of novel heteronuclear complexes of Ln(Ⅲ)-Cu(Ⅱ) with non-cyclic polyether Schiff base

Nine novel heteronuclear complexes of Ln(Ⅲ)-Cu(Ⅱ) with salicylidene tetraethvlcne glycol diamine (SALTTA) have been synthesized and characterized.They have the general formulae [LnCu2(SALTTA)2(NO3)3](NO3)4 3H2O (Ln=La,Pr.Nd,Srn) and [LnCu3(SALTTA)3(NO3)5]-(NO3)4-4H2O (Ln=Gd,Tb,Er,Yb,Y).The IR spectra show that vc=N in the Ln(Ⅲ)-Cu(Ⅱ) het-eronuclear complexes are splitted up into two peaks with a far distance.It has been confirmed that oxygen atoms in oxyethylene of the ligand are not all coordinated to the central metal ions by both IR and NMR methods.     

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.     

Metallotricycle of Lanthanide Supported by a Bridging Diamide: Syntheses and Molecular Structures of {Li(THF)3[LnCl(μ2-trans-1,2-(NSiMe3)2C6H10)(μ2-Cl)]}2•2THF (Ln＝Yb, Nd)

The reactions of dilithium salt of trans-1,2-bis（trimethylsilylamino）cyclohexane with anhydrous lanthanide trichlorides LnCl3 （Ln = Yb, Nd） in THF afforded the dianionic binuclear tricycles of lanthanide chlorides {Li（THF）3[LnCl（μ2-trans-1,2-（NSiMe3）2C6H10）（μ2-Cl）]}2·2THF （Ln=Yb 1, Nd 2） in moderate yields. Both of the bridged complexes were characterized by elemental analysis, IR spectroscopy and single-crystal X-ray diffraction. Crystal structural analysis shows that the two complexes are the analogues which have a tricyclic framework built by two bridged lanthanide metals, four nitrogens and four carbons from two diamide ligands. Each lanthanide metal coordinates to three nitrogen atoms and two chlorines to form a distorted trigonal bipyramid and connects with a lithium by a bridging chlorine.     

Synthesis of indenyllanthanide amides:the effective initiators for polymerization of methyl methacrylate

Diisopropylamido bisindenyl lanthanides(C9H7)2LnN(i-Pr)2(Ln=Gd(1),Y(2),Er(3))were successfully synthesized in satisfied yield by the reaction of Ln(N(i-Pr)2)3(THF)with indene in 1:2 molar ratio in toluene.All of the complexes exhibit very high catalytic activity in the polymerization of methyl methacrylate.The resulting polymers have narrow molecular weight distributions and high syndiotacticity.     

Structures and magnetic properties of several novel lanthanide coordination polymers based on thiophene-2,5-dicarboxylic acid

Eight novel lanthanide complexes: {Ln(TDA)1.5(H2O)2}n (Ln = Pr(1a), Nd(2a)) and {Ln(TDA)(Ac)(H2O)}n (Ln = Pr(1), Nd(2), Eu(3), Gd(4), Tb(5), Dy(6); TDA = Thiophene-2,5-dicarboxylic acid anion) have been constructed by hydrothermal reaction. Structural analyses reveal that complexes 1a and 2a belong to the space group C2/c, exhibiting three-dimensional (3D) frameworks. Complexes 1-6 with P21/c space group were prepared in the presence of excessive ammonium acetate, giving rise to interesting 3D frameworks different from those of 1a and 2a. Magnetic property studies of 4-6 reveal the weak antiferromagnetic interaction exists between adjacent Gd3+ in 4. The complex 6 displays rather rare slow magnetization relaxation behavior in 3D frameworks.     

Synthesis and catalytic activity of novel heteronuclear Ln(Ⅲ)-Cu(Ⅱ) complexes with noncyclic polyether-amino acid Schiff base

A series of novel heteronuclear Ln(Ⅲ)-Cu(Ⅱ) complexes with noncyclic polyether-amino acid Schiff base were synthesized. The general formula is [LnCu_2(H_2TALY)(NO_3)_5](NO_3)_2' nH_2O(Ln=La, Nd, Sm, Gd, n= 4; Ln=Yb, Y, n=3), where H_2TALY = tetraglycol aldehyde bis-lysine Schiff base. It is the first time to report the synthetic method for this new Cu(Ⅱ) complexes and Ln(Ⅲ)-Cu(Ⅱ) heteronuclear complexes. The complexes were characterized by elemental analysis, IR spectra, TG-DTA, magnetic susceptibility, and especially by a 500 MHz NMR spectrometer for 2D-COSY NMR. Coordination mechanism and structures of complexes have been suggested as well. Of particular interest is the potential that the novel complexes obtained may be used as a catalyst, which prompted us to investigate them. It shows 100% conversion with the viscosity-average molecular weight 120 000 for the polymerization of methyl methacrylate (MMA) without addition of any cocatalyst. Furthermore, the complexes with such aliphatic Schiff bas     

Studies on synthesis and magnetic resonance of lanthanide complexes with novel Schiff base derived from noncyclic polyether and P-diketone

Nine Ln( Ⅲ ) complexes with a novel Schiff base derived from diglycolamine and benzoylacetone (BZDA) have been synthesized and characterized. They can be formulated as [Ln2(BZDA)3(NO3)3](NO3)3· nH2O(Ln=La, Pr, Nd, Sm, n = 4; Ln=Gd, Tb, Er, Yb, Y, n = l). Enamic form mechanism in this β-diketone Schiff base and its complexes were suggested and proved by IR, UV and NMR methods. The 13C spin-lattice relaxation time T1 and the ratios of r(ci-Ln)/r(cj-Ln) were measured by a 500 MHz NMR instrument for elucidating the formation of the stable sk-membered chelate ring structure in these complexes. The EPR spectrum of the Gd( Ⅲ ) complex exhibits the "U" spectral feature and "zero field effect". On the basis of them, the crystal field strength and the local symmetry around Gd3 in the complex have been discussed.     

Syntheses and Crystal Structures of Three Coordination Complexes Based on Ln(Ⅲ) and mpca-Ligand

Three complexes obtained by the reaction of Pr(Ⅲ) or Nd(Ⅲ) salts with 5-methyl-2-pyrazinecarboxylic acid(Hmpca) are structurally determined by single-crystal X-ray diffraction.Complex [Pr(mpca-)3(H2O)2]2·6H2O(1) is composed of dinuclear Pr(Ⅲ) units with two metal centers bridged by two anionic mpca-ligands in a κ3O,O':O' bridging mode.Complexes [Pr(mpca-)3]n(2) and [Nd(mpca-)3]n(3) are isostructures,and they consist of polymeric chains based on Ln(Ⅲ) and mpca-ligands.Each pair of adjacent metal centers is linked by three mpca-molecules in a κ3N,O:O bridging mode.     

STYRENE POLYMERIZATION BY OGANOLATHANIDE COMPLEXS[(Bu~tCp)_2LnCH_3]_2 (Ln=Pr,Nd,Gd)

Complexes(Bu~tCp)_1LmC1 react with LiCH_3 in molar ratio of 1:1 to give theneutral methyl complexes[Bu~tCp)_2LnCH_3]_2 (Ln=Pr,Nd,Gd).The complexes alone showmodest catalytic activity for the polymerization of styrene.The polymerizationactivity depends markedly on lanthanide elements.The activity order is Na Pr Gd and the polymerization mechanism was proposed.     

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 and Crystal Structures of Benzyl-and Cyclopentyl-Cyclopentadienyl Sodium Tetrahydrofuranate Complexes

The present paper covers syntheses and crystal structures of benzyl- and cy-clopentyl-cyclopentadienyl sodium tetrahydrofuranate complexes C6H5CH2C5H4Na·THF (1) and C5H9C5H4Na°THF (2). X-ray diffraction data of the title compounds were collected at a low temperature (about 210K). Structures of both the crystals belong to monoclinic space group P21/n with α=0. 9316(3) nm, b=1. 5161(4) nm, c= 0.9791(3) nm, β=91. 06(3)°Z=4 for (1) and α=1. 6120(7) nm, b=0. 9370(3) nm, c=1. 8475(7) nm, β=109.52(3)°Z = 8 for (2). Both structures were solved by using direct methods and refined by block-matrix least-squares to final values of R = 0. 044 for 520 observed reflections (1) and R = 0. 067 for 921 observed reflections (2). In the crystals the tetrahydrofuranate complexes C6H5CH2C5H4Na·THF and C5H9C5H4Na·THF adopt a puckered chain structure with η5-(C6H5CH2)C5H4 and η5-(C5H9)C5H4 rings connected by a bridge Na (THF) unit.     

Mononuclear and Dinuclear Yttrium Complexes Supported by Pyrrolide Ligands: Syntheses,Structures and Catalytic Behaviors towards the Ring-opening Polymerization of ε-Caprolactone

The syntheses, structures and catalytic activities of two yttrium complexes supported by pyrrolide ligands are reported. Treatment of Y(N(Si Me3)2)3 with one equivalent of H3bptd(H3bptd = 1,9-bis(2-pyrrolyl)-2,5,8-triazanona-1,8-diene) in THF gave a complex of composition [Y(bptd)(THF)]2(1). Reaction of Y(N(Si Me3)2)3 with one equivalent of H3tpa(H3tpa = tris(pyrrolyl-?-methyl)amine) in THF generated [Y(tpa)(THF)3](2) in good yield. Complexes 1and 2 have been characterized by single-crystal X-ray diffraction, elemental analyses and NMR spectroscopy. Complex 1 is dinuclear. The two metal centers are doubly bridged by two amine nitrogen atoms to form a Y–N–Y–N four-membered rhombus ring. The geometries of Y3+ ions in 1and 2 are well described as pentagonal bipyramid and capped octahedron, respectively. The ring-opening polymerization reactions of ?-caprolactone initiated by 1 and 2, respectively, were investigated. They both exhibited good catalytic activity for the polymerization of ?-caprolactone. All of the obtained polymers have high molecular weights and relatively narrower PDIs. The polymers generated by 2 possessed polydispersity close to 1.1. The good catalytic activities of 1 and 2 reveal their potential applications in polymer industry.     

Syndiotactic polymerization of styrene and copolymerization with ethylene catalyzed by chiral half-sandwich rare-earth metal dialkyl complexes

The syndiotactic polymerization of styrene(St) and the copolymerization of St with ethylene(E) were carried out by using a series of chiral half-sandwich rare-earth metal dialkyl complexes(Cp~x*) as the catalysts. The complexes are Ln(CH_2SiMe_3)_2(THF)(1-4: Ln = Sc(1), Ln = Lu(2), Ln = Y(3), Ln = Dy(4)) bearing chiral cyclopentadienyl ligand containing bulky cylcohexane derivatives in the presence of activator and AliBu_3. For the St polymerization, a high activity up to 3.1 × 10~6 g of polymer mol Ln~(-1)·h~(-1) and a high syndiotactic selectivity more than 99% were achieved. The resulting syndiotactic polystyrenes(sPSs) have the molecular weights(Mn) ranging from 3700 g·mol~(-1) to 6400 g·mol~(-1) and the molecular weight distributions(Mw/Mn) from 1.40 to 5.03. As for the copolymerization of St and E, the activity was up to 2.4 × 10~6 g of copolymer mol Sc~(-1)·h~(-1)·MPa~(-1), giving random St-E copolymers containing syndiotactic polystyrene sequences with different St content in the range of 15 mol%-58 mol%. These results demonstrate that the bulky cyclopentadienyl ligands of the chiral half-sandwich rare-earth metal complexes effectively inhibit the continued insertion of St monomers into the(co)polymer chain to some extent in comparison with the known half-sandwich rare-earth metal complexes.     

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.     

Synthesis,Structure and Properties of Three-dimensional Gd(Ⅲ),Eu(Ⅲ) Coordination Polymers via in situ Decarboxylation

Two three-dimensional lanthanide(Ⅲ) coordination polymers with the formula [Ln(PYDC)(NA)(H2O)]n [Ln=Gd(1), Eu(2), H2PYDC=pyridine-2,5-bicarboxylic acid, HNA=nicotinic acid] have been hydrothermally synthe- sized and characterized by elemental analysis, IR, and single crystal X-ray diffraction. The NA came from in situ decarboxylation of the part of PYDC. X-ray single crystal structural analyses reveal that complexes 1 and 2 are iso- morphous, they possess the 43·63 topology assembled by Gd3+/Eu3+ and two di...     

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.