Metal ion and anion coordination in the thiamine-[Pt-II(NO2)(4)](2-) system. Structures of a metal complex, Pt(thiamine)(NO2)(3), and two salts, (H-thiamine)[Pt(NO2)(4)]center dot 2H(2)O and (thiamine monophosphate)(2)[Pt(NO2)(4)]center dot 2H(2)O

Reaction of thiamine or thiamine monophosphate (TMP) with K2Pt(NO2)(4) afforded a metal complex, Pt(thiamine)(NO2)(3) (1), and two salt-type compounds, (H-thiamine)[Pt(NO2)(4)]. 2H(2)O (2) and (TMP)(2)[Pt(NO2)(4)]. 2H(2)O (3), which were structurally characterized by X-ray diffraction. In 1, the square-planar Pt2+ ion is coordinated to the pyrimidine N(1'), a usual metal-binding site, and three NO2- groups. The thiamine molecule exists as a monovalent cation in 1 and a divalent cation in 2 while the TMP molecule is a monovalent cation in 3. In each compound, thiamine or TMP adopts the usual F conformation and forms two types of host-guest-like interactions with anions, which are of the bridging forms, C(2)-H . . . anion . . . pyrimidine-ring and N(4'1)-H(...)anion(...)thiazolium-ring. In 3, there is an additional anion-bridging interaction between the pyrimidine and thiazolium rings of TMP, being of the form C(6')-H . . . anion . . . thiazolium-ring. The salts 2 and 3 show similar hydrogen-bonded cyclic dimers of thiamine or TMP between which the anions are held. Results are compared with those of the other thiamine-platinum complexes. (C) 2001 Elsevier Science B.V. All rights reserved.

Hydrothermal synthesis and crystal structure of [{Cu(2,2 '-bpy)(2)}(2)Mo8O26]: a beta-octamolybdate cluster covalently bonded to two {Cu(2,2 '-bpy)(2)}(2+) coordination complexes via bridging oxo groups

An organic-inorganic hybrid solid, (Cu(2,2'-bpy)(2))(2)Mo8O26, has been hydrothermally synthesized and structurally characterized by single-crystal X-ray diffraction. Dark green crystals crystallize in the orthorhombic system, space group Pna21, a = 24.164(5), b = 18.281(4), c = 11.877(2) Angstrom, alpha = 90 degrees, beta = 90 degrees, gamma = 90 degrees, V= 5247(2) Angstrom (3), Z = 4, lambda (MoK alpha) = 0.71073 Angstrom (R(F) = 0.0331 for 5353 reflections). Data were collected on a Siemens P4 four-circle diffractometer at 293 K in the range 1.69 degrees < theta < 25.04 degrees using the omega -scan technique. The structure was solved by the direct method and refined by full-matrix least squares on F-2 using SHELXL-93. The structure of this compound consists of discrete (Cu(2,2'-bpy)(2))(2)Mo8O26 clusters, constructed from beta -octamolybdate subunits ((Mo8O26)(4-)) covalently bonded to two (Cu(2,2'-bpy)(2))(2+) coordination complexes via bridging oxo groups that connect two adjacent molybdenum sites. (C) 2001 Academic Press.

Allyl containing iron post-metallocene catalyst for ethylene polymerization

Tridentate ligand[(2,6-ArN=C(Me))(2)C5H3N](Ar=4-allyl-2,6-(i-Pr)(2)C6H3)(4)which contains allyl groups on each aryl ring was ready prepared and reacted with FeCl2. 4H(2)O to give the precatalyst [(2,6-ArN=C(CH3))(2)C5H3N]. FeCl2 (5). Compounds 2-5 were characterized by H-1 NMR, EI-MS,and IR. The complex 5 which was actived by methylaluminoxane(MAO) exhibits high activity for ethylene polymerization [1.9 x 10(6) g pE.(mol Fe . h)(-1) at 0 degreesC]. It was showed that the activity was decreased with increasing temperature and the polymer product was highly linear PE with (M) over bar (eta) varying from 50000 to 260000.

Copolymerization of carbon dioxide and propylene oxide with Ln(CCl3COO)(3)-based catalyst: The role of rare-earth compound in the catalytic system

A highly alternative copolymer of carbon dioxide and propylene oxide was obtained using a lanthanide trichloroacetates-based ternary catalyst. The rare-earth compound in the ternary catalyst was critical to dramatically raise the yield and molecular weight of the copolymer in addition to maintaining a high alternating ratio of the copolymer. (C) 2001 John Wiley & Sons, Inc.

Hydrothermal synthesis of the two-dimensional coordination polymer {[Fe(phen)(OH)](bta)(0.5)}(n) (phen=1,10-phenanthroline, bta=benzene-1,2,4,5-tetracaboxylate)

The title two-dimensional coordination polymer was synthesised and characterised by X-ray diffraction analysis.

Preparation and application of a novel core-shell-particle-supported zirconocene catalyst

The use of functional groups bearing silica/poly(styrene-co-4-vinylpyridine) core-shell particles as a support for a zirconocene catalyst in ethylene polymerization was studied. Several factors affecting the behavior of the supported catalyst and the properties of the resulting polymer, such as time, temperature, Al/N (molar ratio), and Al/Zr (molar ratio), were examined. The conditions of the supported catalyst preparation were more important than those of the ethylene polymerization. The state of the supported catalyst itself played a decisive role in both the catalytic behavior of the supported catalyst and the properties of polyethylene (PE). IR and X-ray photoelectron spectroscopy were used to follow the formation of the supports. The formation of cationic active species is hypothesized, and the performance of the core-shell-particle-supported zirconocene catalyst is discussed as well. The bulk density of the PE formed was higher than that of the polymer obtained from homogeneous and polymer-supported Cp2ZrCl2/methylaluminoxane catalyst systems. (C) 2001 John Wiley & Sons, Inc.

A new type of polymer-supported metallocene catalyst for ethylene polymerization

A new polymer-supported metallocene catalyst has been prepared, The polymer-supported metallocene displayed considerably high activity in ethylene polymerization, the highest being 3.62x10(7) gPE/molZr.h, the molecular weight of the polyethylene produced was Mn = 1.29x10(5). about 3-4 times those of corresponding homogeneous zirconocenes. The polymer-supported metallocene keeps the characteristics of homogeneous metallocene catalysts, and offers some features, such as adaptable to gas phase and slurry processes: easy to prepare in low cost: relatively high activity and lower MAO/Zr ratio; lower inorganic residues in the polyolefins as compared to cases of SiO2, Al2O3 or MgCl2; unitary active structure, no complex surface as with SiO2; good control of morphology of the resulting polymer.

Preparation of poly(4-vinylpyridine)/silica hybrids supported cyclopentadienyltitanium trichloride (CpTiCl3) catalyst and styrene polymerization

Poly(4 - vinylpyridine)/silica( PVP/SiO2) organic - inorganic nanoscale hybrid was prepared using sol - gel method, in which PVP was used as an organic component and TEOS as a SiO2 precusor, This hybrid was used as CpTiCl3 support. The XPS and IR measurements showed that two kinds of catalytic active site were formed through analyzing the interaction mode between support and CpTiCl3. The results of styrene polymerization showed that syndiotactic was the highest at 50 degreesC. The catalytic activity was 1.09 x 10(6) g PS/ (mol Ti . h) at 70 degreesC when n(Al)/n(Ti) = 1500. GPC results showed a bimodal molecular weight distribution.

Studies on the coordination of Pr(III) with adrenaline by potentiometry and absorption spectroscopy

The stability constant for complex of Pr(III) with adrenaline has been determined by potentiometric titration under biological conditions (37 degrees C and 0.15 mol/L NaCl). The absorption spectra of the Pr(III)-adrenaline system exhibit characteristic bands of Pr(III) at lower pH values. However, the charge transfer band which is due to the coordination of Pr(III) with adrenaline has been observed at higher pH values.

A manganese molybdenum phosphate with a tunnel: hydrothermal synthesis, structure and catalytic properties of (NH3CH2CH2NH3)(10-)H3O)(3)(H5O2)Na-2[MnMo12O24(OH)(6)(PO4)(4)(PO3OH)(4)]-[MnMo12O24(OH)(6)(PO4)(6)(PO3OH)(2)] center dot 9H(2)O

A manganese molybdenum phosphate, (NH3CH2CH2NH3)(10)(H3O)(3)(H5O)Na-2[MnMo12O24(OH)(6) (PO4)(4)(PO3OH)(4)][MnMo12O24 (OH)(6)(PO4)(6)(PO3OH)(2)]. 9H(2)O, has been hydrothermally synthesized and structurally characterized by single crystal X-ray diffraction. The structure of this compound may be considered to be two [Mo6O12(OH)(3)(PO4)(2)(HPO4)(2)](7-) units bonded together by a manganese atom, although several P-O groups are not protonated on account of coordination to a Na+ cation. One-dimensional tunnels were formed in the solid. A probe reaction of the oxidation of acetaldehyde with H2O2 using this compound as catalyst was carried out in a liquid-solid system, showing that the manganese molybdenum phosphate has high catalytic activity in the reaction.

Controlled synthesis of L-lactide-b-epsilon-caprolactone block copolymers using a rare earth complex as catalyst

Well-defined block copolymers of L-lactide-b-epsilon-caprolactone were synthesized by sequential polymerization using a rare earth complex, Y(CF3COO)(3)/Al(iso-Bu)(3), as catalyst system. The compositions of the block copolymers could be adjusted by manipulating the feeding ratio of comonomers. The characterizations by GPC, H-1 NMR, C-13 NMR, and DSC displayed that the block copolymer, poly(epsilon-caprolactone-b-L-lactide) [P(CL-b-LLA)], had a narrow molecular weight distribution and well-controlled sequences without random placement.

A nickel molybdenum phosphate with tunnel: Hydrothermal synthesis and structure of (NH3CH2CH2NH3)(4)center dot(NH3CH2CH2NH2)center dot Na center dot[Ni2Mo12O30(PO4)(HPO4)(4)(H2PO4)(3)]center dot 6H(2)O

A nickel molybdenum phosphate, (NH3CH2CH2NH3)(4).(NH3CH2CH2NH2). Na .[Ni2Mo12O30(PO4)(HPO4)(4)(H2PO4)(3)]. 6H(2)O, invoicing molybdenum present in V oxidation, has been hydrothermally synthesized and structurally characterized by single crystal X-ray diffraction. Deep brown-red crystals are formed in the triclinic system, space group P (1) over bar, a = 12,011(2), b = 14,612(3), c = 21.252(4) Angstrom, alpha = 80.54(2)degrees, beta = 83.10(2)degrees, gamma = 76.29(2)degrees, V = 3561.4(12) Angstrom(3), Z = 2, lambda(MoK alpha) = 0.71073 Angstrom (R(F) = 0.0529 for 9880 reflections), Data mere collected on a Siemens P4 diffractometer at 20 degrees C in the range of 1.75 degrees < theta < 23.02 degrees using the omega-scan technique. The structure was solved by direct methods using the program SHELXTL-93 and refined with the method of fun-matrix least-squares on F-2. The structure of the title compound may be considered to be two [Mo6O15(HPO4)(H2PO4)(3)](5-) units bonded together with a nickel atom, although several P-O groups are not protonated on account of coordination with a Na+ cation, The one-dimensional tunnels were formed in the solid of the title compound. A probe reaction of the oxidation of acetaldehyde with H2O2 using the title compound as catalyst was carried out in a liquid- solid system, showing that the title compound had high catalytic activity in the reaction, (C) 1999 Academic Press.

Lanthanide coordination polymers with dicarboxylate-like ligands: crystal structures of polymeric lanthanum(III) and terbium(III) complexes with flexible double betaines

Four novel polymeric lanthanide(III) complexes of two new double betaine derivatives have been synthesized and structurally determined. In [{La-2(L-1)(2)(H2O)(9)}(n)]Cl-6n. 2nH(2)O (1) and [{Tb(L-1)(H2O)(4)}(n)]Cl-3n. nH(2)O (2) (L-1 =4,4'-trimethylenedipyridinio-N,N'-diacetate), the lanthanide(III) ions form a two-dimensional layer in which each pair of lanthanide(III) ions is bridged by two syn-anti mu-carboxylato-O,O' groups. Adjacent layers are cross-linked through hydrogen bonds among aqua ligands, lattice water molecules and chloride ions, to form a three-dimensional network. Isomorphous [{Ln(L-1)(H2O)(4)}(n)]Cl-3n. 5nH(2)O (Ln=La, 3; Ln=Tb, 4; L-2=1,3 bis(pyridinio-4-carboxylato)-propane) each contain a centrosymmetric paddle-wheel-like dimeric unit in which each pair of adjacent metal atoms is bridged by four syn-syn mu-carboxylato-O,O' groups that are oriented nearly perpendicular to each other about the metal-metal axis. Neighboring dimeric subunits are bridged by a pair of flexible LL ligands into a polymeric chain. Adjacent chains are inter-linked by hydrogen bonds among aqua ligands, lattice water molecules and chloride ions into a three-dimensional network. (C) 1999 Elsevier Science Ltd. All rights reserved.

Synthesis, crystal structure and luminescence studies of a lanthanide coordination polymer with a new double betaine ligand

A novel europium(III) coordination polymer with a new double betaine derivative, {[Eu(L')(NO3)(H2O)(3)](NO3)(2). 3.5H(2)O}(n) (L-1 = 1,3-bis(pyridinio-4-carboxylato)-propane) has been synthesized and its structure determined. Its luminescence properties have also been studied. The title metal carboxylate coordination polymer contains centrosymmetric dimeric units in which each pair of metal ions is linked by a pair of syn-anti carboxylato-O,O' groups, and each pair of such dimeric units is bridged by the backbones of L-1 ligands to form infinite double chains in the b direction. These metal carboxylate chains are further cross-linked by hydrogen bonds among both coordinated and discrete nitrate anions, aqua ligands and lattice water molecules to form a three-dimensional network. Luminescent data show that the L-1 ligand is a good energy donor and the complex has a relatively long luminescent lifetime.

The effect of preparation conditions on the catalyst Nd(P-507)(3)/H2O/Al(i-Bu)(3) for the polymerization of styrene

The catalyst system neodymium phosphonate Nd(P-507)(3)/H2O/Al(i-Bu)(3) for the polymerization of styrene was examined. Effects of the addition order of the catalyst components, catalyst aging time and aging temperature on the catalyst activity and the polymer characteristics were investigated. The catalyst activity for isospecific polymerization of styrene increases with aging time and reaches the maximum with a catalyst aged for 45 min at 70 degrees C. The aging time that the catalyst needs to reach the highest activity for isospecific polymerization decreases with increasing aging temperature. The preformed catalyst and the in situ catalyst were compared with respect to the kinetic behavior of the styrene polymerization and the polymer characteristics.