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991.
992.
993.
T. A. Carlson M. O. Krause W. A. Svensson P. Gerard F. A. Grimm T. A. Whitley B. P. Pullen 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1986,2(4):309-318
The general properties of the Cooper minimum in molecules are reviewed. Experimental results from synchrotron radiation together with theoretical calculations are presented on both the partial cross sections and angular distribution parameters, β. A detailed examination of HCl is used as an example. Previously unpublished results on CCl n H4?n , CCl n F4?n , ethylene dichloride, I2 and ICl are included. The Cooper minimum is largely discussed as a perturbation from atomic behavior, and is examined as a function of atomic number. The Cooper minimum is also examined as a function of chemical environment. Finally, needs for future research are briefly described. 相似文献
994.
Through the use of an ultrasonic slurry mixer, graphite furnace atomic absorption spectrometry (GFAAS) can be applied for the fully automated determination of particulate iron and nickel in edible oils and fats. The unsupervised ultrasonic slurry autosampler yields the same accuracy and somewhat better precision than the much more laborious manual GFAAS method. 相似文献
995.
Kapteijn GM Grove DM Kooijman H Smeets WJ Spek AL van Koten G 《Inorganic chemistry》1996,35(2):526-533
Reaction of palladium acetate with 2 equiv of sodium phenoxide in the presence of a chelate diamine ligand affords the complexes [Pd(OPh)(2)(N approximately N)] (N approximately N = bpy (1), tmeda (2), teeda (3), dpe (4), dmap (5)). These yellow to orange bis(phenoxo)palladium(II) complexes are thermally stable at room temperature in the solid state as well as in solution. Addition of an excess of pentafluorophenol to 1, 2, 4, and 5 affords crystalline complexes [Pd(OC(6)F(5))(2)(N approximately N)] (N approximately N = bpy (6), tmeda (7), dpe (8), dmap (9)). Crystals of 1 and 6 have been subjected to X-ray diffraction studies. Crystals of 1 are orthorhombic, space group P2(1)2(1)2(1) (no. 19), with a = 6.7655(6) ?, b = 16.0585(10) ?, c = 16.7275(13) ?, and Z = 4. Crystals of 6 are triclinic, space group P&onemacr; (no. 2), with a = 7.567(4) ?, b = 12.708(3) ?, c = 12.912(5) ?, alpha = 61.51(3) degrees, beta = 74.74(4) degrees, gamma = 88.78(4) degrees, and Z = 2. The molecular structures of 1 and 6 show them to be square-planar complexes, and the main structural difference between these complexes is the orientation of the aromatic rings. In 6 the OC(6)F(5) ligands are almost parallel in a face-to-face orientation (pi-pi stacking interactions), whereas in 1 the OC(6)H(5) units are skewed away from each other. An unexpected "mixed" alkoxo(aryloxo) complex [Pd(OCH(CF(3))(2))(OPh)(bpy)].HOPh (10) is formed when 1 is reacted with 1,1,1,3,3,3-hexafluoro-2-propanol. The molecular structure of 10 shows O-H.O hydrogen bonding (O.O = 2.642(8) ?) between the hydroxyl hydrogen of phenol and the oxygen atom of the phenoxide ligand as well as an additional C-H.O contact (C.O) = 2.95(1) ?), which can be regarded as the initial stage of a base-assisted beta-hydrogen elimination. Crystals of 10 are monoclinic, space group P2(1)/c, with a = 8.3241(14) ?, b = 11.0316(17) ?, c = 26.376(3) ?, alpha = 93.01(1) degrees, Z = 4. Spectroscopic data of complexes 1-10 indicate that the oxygen atom of the aryloxide or alkoxide ligand is extremely electron-rich, leading to high polarization of the palladium-to-oxygen bond. The bis(phenoxide) complexes 1, 2, and 4 associate with two molecules of phenol through O-H.O hydrogen bonds to form adducts [Pd(OPh)(2)(N approximately N)].2HOPh (N approximately N = bpy (11), tmeda (12), dpe (13)). The palladium complexes 6-9 with OC(6)F(5) groups show no tendency to form adducts with alcohols. 相似文献
996.
Janssen MD Herres M Zsolnai L Spek AL Grove DM Lang H van Koten G 《Inorganic chemistry》1996,35(9):2476-2483
The synthesis and characterization of the complexes [(eta(5)-C(5)H(4)SiMe(3))(2)Ti(C&tbd1;CSiMe(3))(2)]MX (M = Cu, X = OTf (2), SC(6)H(5) (4), SC(6)H(4)NMe(2)-2 (5), SC(6)H(4)CH(2)NMe(2)-2 (6), S-1-C(10)H(6)NMe(2)-8 (7), Cl (8), (N&tbd1;CMe)PF(6) (9); M = Ag, X = OTf (3)) are described. These complexes contain monomeric MX entities, which are eta(2)-bonded by both alkyne functionalities of the organometallic bis(alkyne) ligand [(eta(5)-C(5)H(4)SiMe(3))(2)Ti(C&tbd1;CSiMe(3))(2)] (1). The reactions of 2 with the Lewis bases N&tbd1;CPh and N&tbd1;CC(H)=C(H)C&tbd1;N afford the cationic complexes {[(eta(5)-C(5)H(4)SiMe(3))(2)Ti(C&tbd1;CSiMe(3))(2)]Cu(N&tbd1;CPh)}OTf (10) and {[(eta(5)-C(5)H(4)SiMe(3))(2)Ti(C&tbd1;CSiMe(3))(2)]Cu}(2)(N&tbd1;CC(H)=C(H)C&tbd1;N)(OTf)(2) (11), respectively. The X-ray structures of 2, 3, and 6 have been determined. Crystals of 2 are monoclinic, space group P2(1)/c, with a = 12.8547(7) ?, b = 21.340(2) ?, c = 18.279(1) ?, beta = 133.623(5) degrees, V= 3629.7(5) ?(3), Z = 4, and final R = 0.047 for 5531 reflections with I >/= 2.5sigma(I) and 400 variables. The silver triflate complex 3 is isostructural, but not isomorphous, with the corresponding copper complex 2, and crystals of 3 are monoclinic, space group P2(1)/c, with a = 13.384(3) ?, b = 24.55(1) ?, c = 13.506(3) ?, beta = 119.21(2) degrees, V = 3873(2) ?(3), Z = 4, and final R = 0.038 for 3578 reflections with F >/= 4sigma(F) and 403 variables. Crystals of the copper arenethiolate complex 6 are triclinic, space group P&onemacr;, with a = 11.277(3) ?, b = 12.991(6) ?, c = 15.390(6) ?, alpha = 65.17(4) degrees, beta = 78.91(3) degrees, gamma = 84.78(3) degrees, V = 2008(2) ?(3), Z = 2, and final R = 0.079 for 6022 reflections and 388 variables. Complexes 2-11 all contain a monomeric bis(eta(2)-alkyne)M(eta(1)-X) unit (M = Cu, Ag) in which the group 11 metal atom is trigonally coordinated by the chelating bis(eta(2)-alkyne) entity Ti(C&tbd1;CSiMe(3))(2) and an eta(1)-bonded monoanionic ligand X. The copper arenethiolate complexes 4-7 are fluxional in solution. 相似文献
997.
Christopher W. Tate Peter B. Hitchcock Gerard A. Lawless Zoltán Benkő László Nyulászi John F. Nixon 《Comptes Rendus Chimie》2010,13(8-9):1063-1072
The molecular structure of the previously reported compound [Mo(CO)3(η6-P3C3But3)] has been determined by a single-crystal X-ray diffraction study. Syntheses and molecular structures are also described for the structurally related compounds [Mo(CO)3(η5-P3C3But3)(Me)(Bun)], [Mo(CO)3(η5-P3C3But3)(H)(Bun)] and [Mo(CO)3(η4-P3C3But3(Me)(Bun)(H)(O)Li(THF)3]. Density functional calculations at the B3LYP/cc-pVDZ(-PP) and BP86/cc-pVDZ(-PP) levels have been carried out on the above complexes and the nature of the bonding between the different rings and molybdenum is discussed. 31P NMR spectroscopic evidence is presented for the existence of the novel complex [Mo(CO)3(η6-P3C3But3)PtCl2(PEt3)] in which the triphosphabenzene ring acts as an overall 8-electron donor to the two metal centres. 相似文献
998.
Marco H.P. Rietveld Lammert Nagelholt David M. Grove Nora Veldman Anthony L. Spek Monika U. Rauch Wolfgang A. Herrmann Gerard van Koten 《Journal of organometallic chemistry》1997,530(1-2):159-167
From the reaction of MeReO3 with the neutral arylamine C6H5CH2NMe2 and the aryldiamine C6H4(CH2NMe2)2−1,3, have been isolated in good yields the 1/1 adduct complex [MeReO3 · C6H5CH2NMe2], 1, and the 2/1 adduct complex [(MeReO3)2 · C6H4(CH2NMe2)2− 1,3], 2, respectively. The X-ray molecular structure of 2 shows that both rhenium centres have a trigonal bipyramidal geometry and in the axial positions of each rhenium centre are one of the NMe2 units of the aryldiamine ligand and a methyl group. The mono(ortho)-chelated arylaminorhenium trioxide complex [ReO3(C6H4CH2NMe2−2], 3, can be synthesized by a transmetallation reaction of ClReO3 with [ZnC6H4CH2NMe2−22] in a 2:1 molar ratio. In a similar way the bis(ortho)-chelated arylaminorhenium trioxide complex [ReO3C6H3(CH2NMe2)2−2,6], 4, can be synthesized by addition of a mixture of [Li2C6H3(CH2NMe2)2−2,62] and ZnCl2 to ClReO3. Complexes 3 and 4 have been isolated as white solids in 66% and 81% yields respectively. The rhenium centre in complex 4 has a bicapped tetrahedral geometry in which the monoanionic C6H3(CH2NMe2)2−2,6− ligand is pseudo-facially bonded with a characteristic N1-Re-N2 angle of 107.7(3)°, a Re-Cipso bond length of 2.112(11) Å and Re-N1 and Re-N2 bond lengths of 2.518(9) Å and 2.480(8) Å respectively. 相似文献
999.
Tris(2-pyridylthio)methane, [Tptm]H, has been employed to synthesize the mononuclear alkyl zinc hydride complex, [κ(3)-Tptm]ZnH, which has been structurally characterized by X-ray diffraction. [κ(3)-Tptm]ZnH provides access to a variety of other [Tptm]ZnX derivatives. For example, [κ(3)-Tptm]ZnH reacts with (i) R(3)SiOH (R = Me, Ph) to give [κ(4)-Tptm]ZnOSiR(3), (ii) Me(3)SiX (X = Cl, Br, I) to give [κ(4)-Tptm]ZnX, and (iii) CO(2) to give the formate complex, [κ(4)-Tptm]ZnO(2)CH. The bis(trimethylsilyl)amide complex [κ(3)-Tptm]ZnN(SiMe(3))(2) also reacts with CO(2), but the product obtained is the isocyanate complex, [κ(4)-Tptm]ZnNCO. The formation of [κ(4)-Tptm]ZnNCO is proposed to involve initial insertion of CO(2) into the Zn-N(SiMe(3))(2) bond, followed by migration of a trimethylsilyl group from nitrogen to oxygen to generate [κ(4)-Tptm]ZnOSiMe(3) and Me(3)SiNCO, which subsequently undergo CO(2)-promoted metathesis to give [κ(4)-Tptm]ZnNCO and (Me(3)SiO)(2)CO. 相似文献
1000.
Stefan Kcher Bernhard Walfort Allison M. Mills Anthony L. Spek Gerard P.M. van Klink Gerard van Koten Heinrich Lang 《Journal of organometallic chemistry》2008,693(11):1991-1996
Nitrile-functionalized NCN-pincer complexes of type [MBr(NC-4-C6H2(CH2NMe2)2-2,6)] (6a, M = Pd; 6b, M = Pt) (NCN = [C6H2(CH2NMe2)2-2,6]−) are accessible by the reaction of Br-1-NC-4-C6H2(CH2NMe2)2-2,6 (2b) with [Pd2(dba)3 · CHCl3] (5a) (dba = dibenzylidene acetone) and [Pt(tol-4)2(SEt2)]2 (5b) (tol = tolyl), respectively. Complex 6b could successfully be converted to the linear coordination polymer {[Pt(NC-4-C6H2(CH2NMe2)2-2,6)](ClO4)}n (8) upon its reaction with the organometallic heterobimetallic π-tweezer compound {[Ti](μ-σ,π-CCSiMe3)2}AgOClO3 (7) ([Ti] = (η5-C5H4SiMe3)2Ti).The structures of 6a (M = Pd) and 6b (M = Pt) in the solid state are reported. In both complexes the d8-configurated transition metal ions palladium(II) and platinum(II) possess a somewhat distorted square-planar coordination sphere. Coordination number 4 at the group-10 metal atoms M is reached by the coordination of two ortho-substituents Me2NCH2, the NCN ipso-carbon atom and the bromide ligand. The NC group is para-positioned with respect to M. 相似文献