129 resultados para Secondary and tertiary structure


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[(Me4C2Cp2SmCl.MgCl2.3THF)THF]2 was prepared by the reaction of Me4C2Cp2MgCl2.4THF (Cp=C5H4, THF = tetrahydrofuran) with SmCl3 in THF. The crystals belong to triclinic space group P-1 with a 12.149(3), b 13.187(4), c 13.810(5) angstrom, alpha 117.23(2), beta 94.07(2), gamma 62.86(2)-degrees, V = 1723.9(1.0) angstrom3. In the molecular structure of the title compound there is a symmetrical centre and a quadrilateral formed by SM, Mg, Cl1, Cl2 atoms. Two centroids of the cyclopentadienyls, bridged by a tetramethylethano group form with three bridging chlorine atoms (Cl1, Cl2, Cl1a) a pseudo-trigonal bipyramid around Sm. Three oxygen atoms of THF and three chlorine atoMS (Cl1, Cl2, Cl3) constitute a distorted octahedron around Mg.

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The complex of (CH3Cp)2Yb . DME (DME = dimethoxyethane) has been synthesized by the reduction with metallic sodium of the corresponding chloride (CH3CP)2YbCl. (CH3CP)2Yb . DME crystallized from DME in the monoclinic space group Cm, with cell constants a = 11.068(3), b = 12.338(4), c = 12.479(4) angstrom; beta = 100.51(2)-degrees, V = 1675(l) angstrom3, and D0 = 1.66 g/cm3 for Z = 4. Least-squares refinement of 1420 unique observed reflections led to final R of 0.0487. This complex can be used as a catalyst for the polymerization of methyl methacrylate (MMA).

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The complexes of Ln(L-Pro)s(H2O)2(ClO4)3(Ln = Pr, Nd and Er. L-Pro = L-Proline) were synthesized and characterized by elemental analysis, IR. spectra and thermal analysis. The singal crystal Pr2(L-Pro)6(H2O)4(ClO4)6 Was also obtained. The crystal belongs to monoclinic, P2(1), a = 0.9879 (3) nm, b = 2.1883 (4) nm, c = 1.3393 (2)nm, beta = 91.23(2)-degrees, V = 2.895(1) nm3, Z = 2. R = 0.035 for 5032 observed reflections. The coordination polyhedron of Pr(III) ion comprises six oxygen atoms from L-Pro molecules and two water molecules. Each L-Pro molecule coordinates to two Pr(III) ions through its carboxyl group which serves as a bridging bidentate ligand to form onedimensional chain structure.

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The title complex was synthesized and characterized by H-1, C-13, Sn-119 NMR and IR spectra. A single crystal X-ray diffraction study confirmed its molecular structure and revealed that 3,4,5-trimethoxy-benzoyl salicylahydrazone was a tridentate and approximately planar ligand. The complex crystallizes in the triclinic space group P1BAR with a = 9.208(3), b = 12.536(2), c = 12.187(4) angstrom, alpha = 113.12(2), beta = 90.58(2), gamma = 81.42(2), V = 1277.5(6) angstrom, Z = 2. The structure was refined to R = 0.033 and R(w) = 0.041 for 3944 observed independent reflections. The tin atom has a distorted trigonal bipyramidal coordination. The Sn-C bond lengths are 2.129(5) and 2.113(5) angstrom (av. 2.121(5) angstrom), the C-Sn-C angle is 123.3(2); the bond length between the tin atom and the chelating nitrogen is 2.173(3) angstrom. Two chain carbon atoms and the chelating nitrogen atom occupy the basal plane. The skeleton of two erect oxygen atoms and the tin atom is bent (O-Sn-O angle = 153.5(1)). In the complex, the ligand exists in the enol-form.

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The reaction of ErCl3 with one equivalent of C5H9C5H4Na generates the complex {[(C5H9C5H4)Er(THF)]2(mu2-Cl)3(mu3-Cl)2Na(THF)2}.THF, which crystallizes from hexane/THF. The X-ray crystal structure determination shows that each erbium is surrounded by one C5H9C5H4 ligand, two mu3-Cl, two mu2-Cl and one THF in a distorted octahedral arrangement.

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The indenylpdolinium dichloride tristetrahydrofuranate (C9H7GdCl2.3THF)THF was prepared and its crystal structure (monoclinic space group P2(1)) determined by X-ray diffraction. In C9H7GdCl2.3THF, Gd, O(1), O(2), O(3) and the centroid of the five-membered indenyl ring form a plane, and Cl(1) and Cl(2) are located at two opposite sides of the plane to give a pseudo-octahedron. The coordination number of Gd is eight.

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The single crystal of heteropoly blue, HsSiMo12O40.12H2O, the reduced product of molybdenum-silicon heteropoly acid, was prepared by electrochemical reduction and evaporation in nitrogen atmosphere. The Crystal structure of the product was determined. The heteropoly blue H8SiMo12O40.12H2O, Crystallizes space group P1BAR a = 1.3769 (3) nm, b = 1.4346 (4) nm, c = 1.4134 (4) nm, alpha = 120.47 (2)-degrees, beta = 110.70 (2)-degrees, gamma = 66.11 (2)-degrees, Z = 2, R = 0.0608. The heteropoly blue anion was determined to have Keggin Structure and alpha-isomer and it remained the structure of the unreduced heteropoly acid anion. But the distortion of the structure and the changes of bond length and bond angle take place obviously. The four Mo5+ Positions were determined in the structure.

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The complex [Nd(L)(CH3CN)(CF3SO3)3] has been synthesized. Where L = 1-methyl-1, 4, 7, 10-tetraazacycldodecane. The crystal structure of the complex has been determined by a four-circle X-ray diffractometer to a final deviation factor B value of 0.0370 and R(w) value of 0.0385 respectively. The crystal is triclinic system, space group P1BAR with a = 0.8738(2), b = 1.2870(3), c = 1.2900(3) nm, alpha = 85.63(2), beta = 87.25(2), gamma = 78.30(2)-degrees, V = 1.41571 (60) nm3, Z = 2, D(c) = 1.92 g/cm3. The neodymium ion is eight-coordinated to forming a distorted square antiprism.

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The five complexes (RC5H4)2M(S2CNBz2)Cl (R = H, CH3; M = Ti, Zr, Hf; Bz = CH2C6H5) have been prepared by the reaction of (RC5H4)2MCl2 with anhydrous sodium salts of dibenzyldithiocarbamate in refluxing CH2Cl2. These complexes have been characterized by elemental analysis, IR and H-1 NMR. X-ray crystal structure determination of Cp2Zr(S2CNBZ2)Cl shows the molecule has a five-coordinate bent metallocene geometry in which the zirconium atom is attached to two eta-5-C5H5 groups, one bidentate dibenzyldithiocarbamate ligand and one chlorine [Zr-Cl, 2.549(1) angstrom; Zr-S, 2.734(1), 2.667(1); Cl-Zr-S, 137.6(1)-degrees and 73.3(1)-degrees; S-Zr-S, 64.3(1)-degrees]. The catalytic system Cp2Ti (S2CNBZ2)Cl-NaH exhibits high initial catalytic activity of hydrogenation of hexene-1 under mild conditions.

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(Li.3DME)[eta(5)-C5H5)3NdC6H5], 1 was synthesized by the reaction of NdCl3.2LiCl, 2 equivalents of cyclopentadienylsodium and one equivalent of phenyllithium in THF at -78-degrees-C, and crystallized from THF and DME. The crystal structure of 1 was determined by X-ray diffraction method at -80-degrees-C. The crystal of 1 is triclinic, space group P1BAR with a = 15.752(6), b = 16.232(3), c = 23.038(7) angstrom, alpha = 108.81(2), beta = 93.31(3), gamma = 108.38(2)-degrees, Z = 6 and D = 1.33 g/cm3. Least-squares refinement (5732 observed reflections) led to a final R of 0.053. The complex consists of disconnected ion pairs of (Li.3DME)+ and [(eta(5)-C5H5)3NdC6H5]-. The neodymium atom was connected to three eta(5)-bonded cyclopentadienyls and one sigma-bonded phenyl in a distorted tetrahedral arrangement with Nd-C(sigma-) 2.593(17), 2.613(13) and 2.601(13) angstrom.

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The title complex has beep synthesized by the reaction of CaCl2, with trimethyl phosphate. Its Infrared spectra from 4000 to 100 cm(-1) measured. The assignment of acme absorption bands was discussed. It is found that the stretching vibrations of bridge groups O-P-O are divided into two groups according to their bond length. The crystal structure of the complex boa been determined from single crystal K-ray diffraction data. The crystals belong to monoclinic system, space group P2(1)/c with cell parameteras, a = 1,0704(4), b = 0.5093(2), c = 1.9737(6)nm, beta = 96.23(3)degrees, V = 1.0696(6)nm(2), Z = 4, final R = 0.044. Copper ion is coordinated to five Rimester oxygen atoms to form a distorted square pyramid. The adjacent copper ions are connected by symmetric and non-symmetric bridge groups of O-P-O, forming an infinite one-dimensional chain coordination polymer.

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Bis(t-butylcyclopentadienyl)lanthanide chloride (Ln = Nd or Gd) reacts with one equivalent of methyllithium in ether/tetrahydrofuran to give the complex [(C5H4tBu)2LnCH3]2 (Ln = Nd or Gd). The structure of [(C5H4tBu)2NdCH3]2 has been determined by X-ray analysis. The crystals are monoclinic of space group Cm with a = 9.538(2), b = 23.298(4), c = 9.505(3) angstrom, beta = 119.53(2)-degrees, V = 1828.0(7) angstrom 3, D(calc.) = 1.458 g/cm3 and Z = 2 for the dimer. The two (C5H4tBu)2Nd units in the dimer are connected by asymmetrical methyl bridges with independent Nd-C bond lengths of 2.70(2) and 2.53(2) angstrom and Nd-C-Nd angles of 94.7(9) and 87.3(6)-degrees.

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Bis(methylcyclopentadienyl)chloro(alpha-naphthoyloxy)zirconium, (CH3C5H4)2Zr Cl(alpha-C10H7COO), has been synthesized by the reaction between (MeCp)2ZrCl2 and equimolar sodium alpha-naphthoate in toluene at room temperature. The molecular structure of the title complex was determined by X-ray diffraction. The molecules have a five-coordinate bent metallocene structure in which the alpha-naphthoxyligand is bidentate [Zr-O, 2.317(2), 2.260(2) angstrom]. The remaining distances are [Zr-Cl, 2.521(1) angstrom; Zr-C, 480-2, 565 angstrom; Zr-cent-CH3C5H4 2.217 and 2.230 angstrom].

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The crystal structure of the title compound was determined from single crystal X-ray diffraction at -90-degrees-C. The complex crystallizes in the tetragonal P4/mnc, Z = 2, a = 12.515(3), c = 17.636(7) angstrom. The structure was solved by Patterson and Fourier techniques and refined by least-squares to R = 0.061 for 788 reflections. The central PO4 is disordered, P-O = 1.54 angstrom, M(M = Mo or V) is 6-coordinate, M-O = 1.62-2.48 angstrom, K is 7-coordinate, K-O = 2.84-3.10 angstrom.