1,721,128 research outputs found
Activation of C-H bond by cis-[Pt(NO3)2(PPh3)2], cyclometallation of tetramethylthiourea
No full textReaction of cis-[Pt(NO3)2(PPh3)2] with tetramethylthiourea (tmtu) affords [Pt(PPh3)2(tmtu*)]NO3, in which tmtu* is tetramethylthiourea
deprotonated at one methyl group. An X-ray investigation has shown that tmtu* is cyclometallated with Pt–S and
Pt–CH2 bonds. The likely role of dissociation of the labile nitrato ligands, to give cationic intermediates, is outlined
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
DINUCLEAR HYDROXO COMPLEXES OF PLATINUM(II) WITH GROUP-V CHELATING LIGANDS - CRYSTAL AND MOLECULAR-STRUCTURE OF [(DPP)PT(MU-OH)2PT(DPP)][BF4]2.1/2 CH3OH (DPP = 1,3-BIS(DIPHENYLPHOSPHINO)PROPANE
No full textThe synthesis of a series of dinuclear hydroxo platinum(II) derivatives [(L-L)Pt(mu-OH)2Pt(L-L)][BF4]2, 1-6 [L-L:Ph2PCH2PPh2(dpm), 1; Ph2P(CH2)2PPh2 (dpe), 2; Ph2P(CH2)3PPh2 (dpp), 3; Ph2P(CH2)4-PPh2 (dpb), 4; Ph2P(CH2)2AsPh2 (dpase), 5; Ph2As(CH2)2AsPh2 (dase), 6) has been accomplished by reaction of the mononuclear chlorides Pt(L-L)Cl2 with two equivalents of AgBF4 in methanol solution. The species 1-6 were characterized by FAB-MS, IR and NMR (H-1, P-31{H-1}, and Pt-195{H-1}) spectroscopic techniques: in all cases, complex 1 included, L-L acts as a chelating ligand. The spectroscopic data show that the dimeric unit is maintained in the vapour phase (FAB/MS), in solution (P-31{H-1}), and in the solid state (X-ray). The structure of complex 3 has been determined by single-crystal X-ray diffraction: monoclinic, space group P2(1)/c with a = 23.339(3), b = 14.204(2), c = 17.874(3) angstrom, beta = 110.1 7(2)-degrees, R = 0.043 and R(w) = 0.056 for 5554 observed reflections having I>3sigma(I). Aspects of the reactivity of the hydroxo species with HBF4 under various conditions are discussed
NICKEL CARBIDE CARBONYL CLUSTERS - SYNTHESIS AND STRUCTURAL CHARACTERIZATION OF [NI8(CO)16C]2- AND [NI9(CO)17C]2-
No full textNitrosyl complexes of rhenium. Part 2. Crystal and molecular structure of dihydridonitrosyltris(triphenylphosphine)rhenium(I)?benzene(2/1)
No full textThe crystal and molecular structure of the title compound has been determined by Patterson and Fourier methods from three-dimensional X-ray data collected by diffractometer. Crystals are orthorhombic, space group Pca21, with cell constants a = 25.069(6), b = 18.737(4), and c = 20.644(5) Å. The structure has been refined by least-squares methods to R 0.048 for 2 938 independent reflections. The two crystallographically independent molecules in the asymmetric unit are very similar and exhibit markedly distorted octahedral geometry, with one phosphine ligand, the NO group, and the two hydrido-ligands (mutually cis) in equatorial positions, with the other two phosphine ligands axial, largely bent toward the hydrido H atoms. The three Re-P distances are 2.370(7), 2.439(7), and 2.403(8) Å in the first molecule and 2.401(6), 2.498(8), and 2.386(8) Å; in the second. The nitrosyil groups are linked linearly to the metal atoms, as NO+ ligands, with Re-N 1.77(2) and 1.73(2) and N-O 1.25(3) and 1.24(3) Å; in the two molecules. The largest deviation from ideal geometry is shown by the axial P-Re-P angles [143.4(3) and 143.0(3)°]
Di-, Tetra-, and Polynuclear Copper(II) Complexes : active Catalysts for Oxidation of Toluene and Benzene
No full textThree copper(II) complexes with a binucleating N 2O donor ligand, [Cu 2(L 1)(μ 2-pz)(CH 3COO) 2] (1), [Cu 4(L 1) 2(μ 4- O)(μ 2-CH 3COO) 2(μ 1,1-N 3)(N 3)] (2), and [Cu 2(L 2) (μ 1,1-N 3)(μ 1,3-N 3) 2] ∞ (3) [pz = pyrazolato, HL 1 = 2,6-bis(morpholinomethyl)-4-tert-butylphenol and HL 2 = 2,6-bis(morpholinomethyl)-4-methylphenol] have been synthesized and characterized by elemental analysis, FTIR and UV/Vis spectroscopy, and X-ray crystallography. X-ray crystallographic studies revealed that a series of di-, tetra-, and polynuclear complexes have been formed by varying the bridging ligand, counteranion, and reaction conditions. These show effective catalytic properties for the hydrogen peroxide oxidation of toluene and benzene
A copper(II) complex with rare μ1,1,1-azide ligand : active catalyst for hetrogeneous olefin epoxidation
No full textA copper(II) complex [Cu2L(μ1,1-N3)(μ1,3-N3)(μ1,1,1-N3)] (1) where HL = 4-methyl-2,6-bis(phenylmethyliminomethyl)phenol, with N2O donor ligand was synthesized and characterized by elemental analysis, FT-IR spectra and X-ray crystallography. X-ray crystallographic study reveals that it is a 1D chain along crystallographic b axis and the existence of rare μ1,1,1-azide bridging mode. The complex was immobilized on mesoporous silica and the immobilized compound was used as the active catalyst for the oxidation of olefins using tert-butyl hydroperoxide as oxidant. The results show that corresponding epoxides were produced in high yield with high selectivity
COORDINATION OF SNCL2 AND GECL2 ONTO A ONE-DIMENSIONAL PLATINUM NETWORK - SYNTHESIS AND STRUCTURAL CHARACTERIZATION OF THE [PPH(4)](2)[PT-8(ECL(2))(4)(CO)(10)] (E=SN, GE) COMPLEXES
No full textThe preparation and molecular structures of two anions [Pt-8(ECl(2))(4)(CO)(10)](2-) (E = Sn, Ge), obtained from the reaction of [Pt-15(CO)(30)](2-) with tin dichloride and germanium tetrachloride, are reported; X-ray analysis shows that the two isomorphous and isostructural anions exhibit an array of metal atoms formed by an edge-to-edge condensation of three tetrahedra generating a one-dimensional framework along the ($) over bar 4 axis with four ECl(2) groups capping four independent exposed butterfly surfaces
Carbonyl complexes of Rh(I) and Ir(I) and P-donor ligands as useful ‘‘building blocks’’ for the self-assembly of new organometallic polymers
No full textWe report here on three new 1-D polymeric species, obtained by self-assembly of Rh(I) and Ir(I) complexes of general formula [M(CO)2Cl2]2 (M= Rh, Ir) with bidentate phosphine ligands as 1,2-bis(diphenylphosphino)acetylene (dppa) and trans-1,2-bis(diphenylphosphino)ethene (dppethe)
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