Search results for "Halide"
showing 10 items of 324 documents
Ortho-Metalated Primary Amines. 6.1 The First Synthesis of Six-Membered Palladacycles from Primary Amines Containing Electron-Withdrawing Substituent…
2003
When H 2 N(CH 2 ) 2 C 6 H 4 OMe-4 (RNH 2 ) and Pd(OAc) 2 are reacted in a 2:1 molar ratio, the complex [Pd(OAC) 2 (NH 2 R) 2 ] (1) is obtained. Complex 1 reacts with 1 equiv of Pd(OAc) 2 to give the dinuclear complex [Pd(OAc)(μ-OAc)(NH 2 R)] 2 (2). When complex 2 is heated in acetonitrile at 80 °C, the ortho-metalated complex [Pd{C 6 H 3 (CH 2 ) 2 NH 2 -2-OMe-5-κ 2 C,N}(μ-OAc)] 2 (3a) is obtained. Complex 3a is also prepared by refluxing RNH 2 and Pd(OAc) 2 in a 1:1 molar ratio in acetonitrile. Complex 3a reacts with NaBr or LiCl to afford the complexes [Pd{C 6 H 3 (CH 2 ) 2 NH 2 -2-OMe-5-κ 2 C,N}(μ-X)]2 (X = Cl (3b), Br (3c)). PPh 3 splits the acetate or halide bridge in complex 3a or 3b t…
"Through-space" 31P spin-spin couplings in ferrocenyl tetraphosphine coordination complexes: improvement in the determination of the distance depende…
2008
Abstract From the analysis of several nickel and palladium halide complexes of a constrained ferrocenyl tetraphosphine, the existence in solution phase of unique 31P–31P “through-space” nuclear spin–spin coupling constants (JPP) had been previously evidenced. Due to the blocked conformation of the species in solution, and based on the NMR spectra obtained for the complexes and their corresponding solid state X-ray structures, these JPP constants had been shown to clearly depend on the mutual spatial position of the corresponding phosphorus atoms. Herein, the quantitative correlation disclosed at that time (P⋯P distance dependence of coupling constants) is remarkably confirmed, and mathemati…
Bulky Surface Ligands Promote Surface Reactivities of [Ag141X12(S-Adm)40]3+ (X = Cl, Br, I) Nanoclusters: Models for Multiple-Twinned Nanoparticles
2017
Surface ligands play important roles in controlling the size and shape of metal nanoparticles and their surface properties. In this work, we demonstrate that the use of bulky thiolate ligands, along with halides, as the surface capping agent promotes the formation of plasmonic multiple-twinned Ag nanoparticles with high surface reactivities. The title nanocluster [Ag141X12(S-Adm)40]3+ (where X = Cl, Br, I; S-Adm = 1-adamantanethiolate) has a multiple-shell structure with an Ag71 core protected by a shell of Ag70X12(S-Adm)40. The Ag71 core can be considered as 20 frequency-two Ag10 tetrahedra fused together with a dislocation that resembles multiple-twinning in nanoparticles. The nanocluster…
Role of Halide Ion in the Mechanism of Protonolysis of the Pt-C Bond in Pt(II) Alkyl and Aryl Complexes.
1985
Abstract A mechanistic study is described for the electrophilic cleavage of the Pt C σ bond in complexes cis -[PtPh 2 (PEtPh 2 ) 2 ] and trans -[PtXR(PEt 3 ) 2 ] (X = Cl and Br, R = Me, Et, n-Pr, n-Bu, CH 2 Ph) by the proton in the presence of halide ions in aqueous methanol (MeOH/H 2 O, 91v/v) which yields cis -[PtClPh(PEtPh 2 ) 2 ] and trans -[PtX 2 (PEt 3 ) 2 ], respectively. The reactions are first-order in substrate for both systems and the general bivariate rate law k obs = [H + ]{ k H + k x K [[X − ]}/(1 + K [[X − ]) is obeyed. The proposed mechanism involves a fast pre-equilibrium formation (K) of a platinum(II) anionic intermediate via interaction of the halide with the square-plan…
Intercalation chemistry of superconducting zirconium and hafnium nitride halides
2001
Abstract Lithium intercalation in MNX (M=Zr, Hf; X=Cl, Br) may lead to superconducting compounds with critical temperatures up to 24 K. Electrochemical lithiation experiments agree with the results obtained with chemical methods, as samples with larger capacity on discharge are also those having larger lithium contents after chemical lithiation. Variations exist in the electrochemical profiles of different batches for these compounds indicating differences in the intercalation reaction pathway. High-resolution electron microscopy images confirm the structural model isotypic to SmSI for β-MNX phases. The major part of crystals from ZrNX as well as from the HfNCl samples showing a high lithiu…
Thermal potential of ion-exchange membranes and its application to thermoelectric power generation
2016
The low efficiency and high price of thermoelectric semiconductors has generated interest in unconventional forms of thermoelectric materials. In this article, ionic thermoelectricity has been studied with commercial ion-exchange membranes for different aqueous 1:1 electrolytes. The theory of thermal membrane potential has been derived taking into account the ionic heats of transport, the non-isothermal Donnan potentials, the temperature polarization, and the thermally-induced concentration polarization of the electrolyte. Also the generated thermoelectric power has been experimentally studied. The experiments show good agreement with the theory, and suggest ways for systematic improvement …
Non-Centrosymmetric Tetrameric Assemblies of Tetramethylammonium Halides with Uranyl Salophen Complexes in the Solid State
2010
Ditopic salophen-UO(2) receptors 1-4 and 7 co-crystallize with tetramethylammonium (TMA) chloride and fluoride salts producing good quality crystals amenable for X-ray diffraction characterization. The arrangement of the receptor and salt units in the crystal lattice is such that tetrameric ball-shaped assemblies are formed, where an inner cluster of four TMA cations are surrounded by an outer shell of four UO(2)-bound anions. These elaborate architectures, which occur in all cases, regardless of a certain degree of structural modification on the receptors, lead to lattices that belong to non-centrosymmetric (NCS) space groups. Interestingly, the tetragonal symmetry of the tetrameric ball-s…
The role of cation⋯π interactions in capsule formation: co-crystals of resorcinarenes and alkyl ammonium salts
2008
An unprecented dimeric capsular assembly of a tetramethylated C-hexyl resorcinarene and an expected one from unsubstituted C-butyl resorcinarene with tetramethylammonium cation are described. Surprisingly tetramethylated C-hexyl resorcinarene, with no apparent possibility for intra-capsular hydrogen bonds, forms a capsule which is held together solely by the cation⋯π interactions and the complementary geometry of the spherical guest cation and the concave resorcinarene host. The C-butyl resorcinarene capsule, as in the case of dimeric resorcinarene capsules reported earlier, is mediated viasolvent molecules and intra-capsular hydrogen bonds. We also report here two co-crystals of C-methyl r…
Spectral and structural insights of copper reduction pathways in the system of CuX2-R2S (X=Cl, Br; R=allyl, n-propyl)
2021
Abstract We have explored the behaviour of Cu(II)/Cu(I) redox couple in the system CuX2-R2S, X = Cl, Br; R = allyl, n-propyl, under anhydrous and anaerobic conditions, thus simulating the reduction half cycle in the copper catalyzed oxidation of thioethers. In doing so, the Cl−Br substitution was critical for tuning the reduction potentials, while the replacement of propyl group by allyl group supported the trapping of oxidation by-product, halogen molecules. It was therefore possible to use the spectrophotometric titration, thereby providing information on the distribution of complex species in acetonitrile solution. The study showed that the trinuclear mixed−valence copper (I-II-II) aggre…
Complexes of organometallic compounds
1966
Abstract The compounds (C2H5)2PbCl2, (C2H5)3PbCl and PbCl2 were studied by paper electrophoresis in aqueous LiCl solutions of various molarities. Determination was made of the formation of chloride complexes in which the electric charge was a function of ligand concentration in the solution. From the results of these experiments, and from a comparative examination of anion exchange data obtained in previous researches, useful information is obtained for determining the ligand concentrations relative to the preponderance of cationic, neutral and anionic complexes in the aqueous solutions. From this information it is possible to assume (C2H5)2PbCl42− and (C2H5)3PbCl32− as the fully coordinate…