1,720,982 research outputs found
Carbon-13 NMR Evidence of a Relaxation Process dominated by Scalar Coupling with a Quadrupolar Nucleus in [Re3(u-H)4(CO)10]-
No full textCarbon-13 n.m.r. spin–lattice relaxation times of the anion [Re3(μ-H)4(CO)10]– have been determined at various temperatures and field strengths in order to elucidate the different components of the relaxation mechanism. Scalar coupling with the quadrupolar Re isotopes (185Re, 187Re; I=5//2) proved to be the main relaxation pathway at room temperature in the range 20–68 MHz. Analysis of the data allowed the estimation of the quadrupolar relaxation time of Re and of the coupling constant 1J(187Re–C). The latter has been determined for the first time
Relaxation Studies of Carbonyl Rhenium Clusters. II. Relaxation Mechanisms and Estimation of the 13C Chemical Shielding Anisotropy in the [Re3(u-H)4(CO)10]- Anion at Low Temperature
No full textRelaxation Studies of Carbonyl Rhenium Clusters. Relaxation Mechanisms and Estimation of the 13C Chemical Shielding Anisotropy in the [Re3(u-H)4(CO)10]- Anion at Low Temperatur
Relaxation Studies of Carbonyl Rhenium Clusters. Part 3. 13C NMR Study of the Properties of the Unsaturated Anion [Re3(m-H)4(CO)9(NCMe)]- at Low Temperature
No full textRelaxation Studies of Carbonyl Rhenium Clusters: 13C NMR Study of the Properties of the Unsaturated Anion [Re3(m-H)4(CO)9(NCMe)]- at Low Temperatur
Carbon-13 NMR Investigation of the Properties of the Anion [Re3(u-H)3(CO)10]2- in Solution
No full text13C NMR measurements were performed on [Re3(μ-H)3(CO)10]2− at various temperatures and field strengths. Selective decoupling allowed assignments of the carbonyl resonances. Spin-lattice relaxation time measurements indicated that two mechanisms, scalar coupling and chemical shielding anisotropy, contribute to the relaxation of carbon-13. Variable temperature experiments revealed that more than one mechanism is responsible for the fluxional behaviour
Lipophilic Cage Ligands: Synthesis, Spectroscopic Properties and Applications
Full text linkLipophilic Cage Ligands: Synthesis, Spectroscopic Properties and Application
A Novel Unsaturated Tetrahedral Hydrido-Carbonyl Cluster Anion of Rhenium. Synthesis and X-Ray Characterization of [Re3(u-H)3(m3-H)2(CO)12]-J.
No full textThe reaction of the anion [Re4(μ-H)6(CO)12]2– with acids affords the unsaturated (58 valence electron) anion [Re4H5(CO)12]–, which contains a distorted tetrahedral cluster, with Re–Re bond lengths in the range 2.857(1)–3.251(1)Å, bearing three edge-bridging and two face-capping hydride ligands, completely fluxional in solution down to –90 °C
New Synthesis, Reinvestigation of the Solid-State Structure and NMR Analysis of the Unsaturated Anion Tetrakis(u-hydrido)decacarbonyl-triangulo-trirhenate(1-)
No full textsynthesis and NMR characterization of a Rhenium cluste
NMR Investigation of Lipophilic Cage Ligands. Part 2. Structural Assignments and Conformational Properties of the Ligand 12-hexadecyl-7,17,22,27-tetraoxa-1,4,10,14-tetraazatricyclo (12.5.5.54,10) nonacosane and of its Sodium, Potassium & Silver Complexes
No full textTwo-dimensional homonuclear (COSY, phase-sensitive double quantum filtered COSY) and heteronuclear shift correlated experiments were employed to characterize fully the cylindrical cage ligand 12-hexadecyl-7,17,22,27-tetraoxa-1,4,10,14-tetraazatricyclo[12.5.5.54,10] nonacosane (1) and its sodium, potassium and silver complexes. 13C NMR variable temperature experiments indicated that the free ligand 1 is a mobile molecule in a fast conformational equilibrium at room temperature, whereas its sodium complex is more rigid, some degrees of freedom being allowed in that part of the molecule featuring the longest bridge. The potassium derivative behaves similarly to its sodium counterpart. For the silver complex the differences observed have been attributed to a stronger interaction of the metal ion with nitrogen atoms
Disruption of the Pd(I)-Pd(I) dinuclear structure by reaction of [Pd2(mu-PCy2)(mu- eta-3-C3H5)(PCy2H)2] with benzenethiol: formation and x-ray and NMR characterization of trans- [Pd(SPh)2(PCy2H)2].
No full text[Pd2(mu-PCy2)(mu,eta3-C3H5)(PCy2H)2] reacts with an excess of PhSH to yield the mononuclear complex trans-[Pd(SPh)2(PCY2H)2] which was completely characterized by solution multinuclear NMR spectroscopy and by a single-crystal X-ray diffraction experiment. Crystal data: for trans-[Pd(SPh)2(PCy2H)2]: triclinic, space group P1BAR, a = 10.061(3), b = 13.733(3), c = 14.398(4) angstrom, alpha = 86.46(4), beta = 72.07(2), gamma = 76.57(4)-degrees, U = 1840.9(9) angstrom3, Z = 2, d(calc) = 1.301 g cm-1, R = 0.064, R' = 0.050
An Unusual Species from the Reaction of Unsaturated Anion [Re3(m-H)4(CO)10]- with Me3NO. Synthesis and Spectroscopic Characterisation of the Adduct Anion [Re3(m-H)3(CO)9(m3O·H·NMe)3]- and Crystal and Molecular structure of its Tetraethylammonium salt
No full textAn Unusual Species from the Reaction of Unsaturated Anion [Re3(m-H)4(CO)10]- with Me3NO. Synthesis and Spectroscopic Characterisation of the Adduct Anion [Re3(m-H)3(CO)9(m3O·H·NMe)3]- and Crystal and Molecular structure of its Tetraethylammonium sal
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