scholarly journals Kinetics of ligand exchange between a uranium(IV) β-diketonate and free β-diketone

1977 ◽  
Vol 55 (20) ◽  
pp. 3559-3561 ◽  
Author(s):  
G. Folcher ◽  
N. Keller ◽  
C. Kiener ◽  
J. Paris
Keyword(s):  
Ligand Exchange ◽  
Free Ligand ◽  
Exchange Mechanism ◽  
First Order ◽  
H Nmr ◽  
Coordination Site ◽  
Exchange Kinetics ◽  
Kinetics Of

The intermolecular ligand exchange kinetics between a uranium(IV) β-diketonate and free β-diketone were studied by 1H nmr as a function of temperature and concentration. The reaction was found to be of first order in both chelate and free ligand. The results suggest that the exchange mechanism involves a ninth coordination site in the uranium(IV) chelate.

A NMR Study of the Exchange Kinetics of the Nonamethylimidodiphosphoramide with its Complexes of Diamagnetic Cations

1978 ◽  
Vol 33 (6) ◽  
pp. 684-685 ◽  
Author(s):  
P. R. Rubini ◽  
L. Rodehüser ◽  
J.-J. Delpuech
Keyword(s):  
Nmr Spectroscopy ◽  
Ligand Exchange ◽  
H Nmr ◽  
Nmr Study ◽  
Exchange Kinetics ◽  
Monodentate Ligands ◽  
Kinetics Of

Abstract The ligand exchange on nonamethylimidodiphosphoramide (NIPA) complexes is found to be very slow comparatively to analogous monodentate ligands; the rates determined by 1H or 31P NMR spectroscopy are: k(25°C)=4.3 × 10-2 s-1; 31.6 s-1 • M-1; 3.7 × 104 S-1 • M-1 and 1.35 × 104 s-1 · M-1 for Mg2+, Ca2+, Sr2+ and Li+ cations respectively. For the Al3+, Ga3+, In3+ and Be2+ ions no exchange could be detected by 1H NMR spectroscopy up to 120 °C, indicating rates lower than about 10-3 s-1

Electron exchange kinetics in a tetrahedrally coordinated copper(II)/(I) couple

1995 ◽  
Vol 73 (1) ◽  
pp. 61-69 ◽  
Author(s):  
Peter D. Metelski ◽  
A. Scott Hinman ◽  
Hideo D. Takagi ◽  
Thomas W. Swaddle
Keyword(s):  
Electron Transfer ◽  
Ligand Exchange ◽  
Copper Complexes ◽  
Ligand Substitution ◽  
Electron Exchange ◽  
Tetrahedral Complex ◽  
Pt Electrode ◽  
First Order ◽  
H Nmr ◽  
Exchange Kinetics

The four-coordinate anion CuI(dpym)2− (Hdpym = 3,3′,5,5′-tetramethyl-4,4′-dicarboethoxydipyrromethene) can be prepared in solution in acetone either by electrochemical reduction of the known tetrahedral complex CuII(dpym)20 (E0 = −290 mV vs. SCE) or by the quantitative reaction of 2Hdpym with Cu(CH3CN)4+ in the absence of O2. The latter reaction does not go to completion in solvents that bind relatively strongly to CuI or that are poor proton acceptors. Ligand exchange between CuI(dpym)2− excess Hdpym in acetone is "fast" in the 1H NMR timeframe, with k1 = 1.4 × 107 L mol−1 s−1at 298 K (first order in each reactant), ΔH‡1 = 3.4 ± 0.6 kJ mol−1, and ΔS‡1 = −97 ± 3 J K−1 mol−1. In the absence of excess Hdpym, dissociation of CuI(dpym)2− in acetone remains negligible. Homogeneous electron exchange between CuI(dpym)2− and CuII(dpym)20 in acetone falls in the "slow" 1H NMR timeframe, with kex = 5.9 × 103 L mol−1 s−1, ΔH‡ex = 48.5 ± 3.0 kJ mol−1, and ΔS‡ex = −10 ± 10 J K−1, at ionic strength I ≈ 0.007 mol L−1 and 298 K, while for the same self-exchange on a Pt electrode the heterogeneous rate constant kel = 0.16±0.04 cm s−1 at I ≈ 0.1 mol−1L−1 and 298 K, according to AC voltammetry. These values of Kex and Kel are of the order expected for CuII/I couples in which no significant change in coordination number or geometry accompanies electron transfer. Keywords: Electron transfer, copper complexes, ligand substitution kinetics, dynamic NMR.

scholarly journals Ligand Exchange Kinetics of 2,2’-Bipyridine with Nitrilotriacetatonickelate(II)

2018 ◽  
Vol 6 (2) ◽  
pp. 71-75
Author(s):  
Larry H Kolopajlo ◽  
Shelby Coleman
Keyword(s):  
Rate Constant ◽  
Ligand Exchange ◽  
Order Conditions ◽  
Hydrogen Ion ◽  
Ligand Exchange Reaction ◽  
First Order ◽  
Exchange Kinetics ◽  
Pseudo First Order ◽  
Ph Range ◽  
Kinetics Of

The kinetics of the ligand exchange reaction between 2,2’-bipyridine (bipy) and NiNTA- was studied over the pH range 4.7 to 7.5 at 25.0 0C and an ionic strength of 0.10 M by following the formation of Ni(bipy)3 product at 307 nm. All reactions were run under pseudo-first order conditions with a [bipy]/[NiNTA-] ratio of at least 20. The reaction is first-order with respect to each of NiNTA- and to bipy. The reaction is also accelerated by hydrogen ion. The rate constant for the hydrogen ion unassisted addition of bipy to NiNTA- is 0.671 M-1 s-1. The reaction is also first-order in hydrogen ion with a rate constant for the hydrogen ion assisted addition of bipy to NiNTA- is 9.45 x 104 M-2 s-1. A dissociative type mechanism accelerated by hydrogen ion is proposed. The work has significance by showing that NiEDDA and NiNTA, both aminopolyacrboxylate complexes react by the same mechanism.

Coordination Compounds of Indium. Part XIX. Ligand Exchange Studies with Indium(III) Complexes of Trifluoromethyl-β-diketonates

1972 ◽  
Vol 50 (24) ◽  
pp. 3950-3957 ◽  
Author(s):  
Mrs. G. M. Tanner ◽  
D. G. Tuck ◽  
E. J. Wells
Keyword(s):  
Ligand Exchange ◽  
Coordination Compounds ◽  
Free Ligand ◽  
Intramolecular Proton Transfer ◽  
Zero Order ◽  
Monodentate Ligand ◽  
Ligand Exchange Reaction ◽  
First Order ◽  
Stereochemical Properties ◽  
Coalescence Temperature

The ligand exchange reaction between InL3 con plexes (L = CF3•CO•CH•CO•R− anion; R = methyl, i-butyl, phenyl, 2-naphthyl, and 2-thienyl) and excess free ligand (HL) has been studied in the solvents diisopropyl ketone, acetonitrile, benzene, and dimethylsulfoxide. Studies of the lifetimes of the reactants as obtained from their 19F n.m.r. line-widths show that the exchange is first order in InL3 concentration, but zero order in free ligand concentration. The coalescence temperature for the collapse of the n.m.r. 19F chemical shift between free and complexed ligand (~50 Hz) yields ΔG≠ for the exchange. The results are in agreement with the known stereochemical properties of indium(III) complexes. The rate-controlling process in the exchange is identified as the. rotation of one monodentate ligand about a partial double bond prior to intramolecular proton transfer to a second monodentate ligand.

Isotopic exchange reactions of amines. Part 1. An 2H nuclear magnetic resonance study of the amino to methyl group deuteron exchange in methylamine

1976 ◽  
Vol 54 (23) ◽  
pp. 3775-3782 ◽  
Author(s):  
James D. Halliday ◽  
Patrick E. Bindner
Keyword(s):  
Thermal Decomposition ◽  
Isotopic Exchange ◽  
Equilibrium Mixture ◽  
Nuclear Magnetic Resonance Study ◽  
Exchange Reactions ◽  
Amino Groups ◽  
Thermal Decomposition Product ◽  
First Order ◽  
H Nmr ◽  
Exchange Kinetics

Deuteron exchange kinetics between the methyl and amino groups in methylamine, catalyzed by potassium methylamide (PMA), have been studied by 2H nmr.[Formula: see text]Typical values of kobs, the observed pseudo first-order exchange rate, are 1.0 × 10−5 s−1 at 0.21 M PMA and 323 K. Effects of added potassium methylamide and temperature are described. The rate is unaffected by the thermal decomposition product of PMA and there is little or no catalysis by an equilibrium mixture of the solvated electron species e−, (e−K+), and K−. The active catalyst in solution is shown to be monomeric PMA in equilibrium with relatively inactive dimers, …, n-mers. A mechanism that describes the exchange and relates it to the thermal decomposition of the amide is discussed.

Probing the ligand exchange kinetics of phenynyl-based ligands on colloidal Au nanoparticles

2021 ◽  
Vol 5 (1) ◽  
pp. 465-471
Author(s):  
Ting Xiang ◽  
Jianpeng Zong ◽  
Wenjia Xu ◽  
Yuhua Feng ◽  
Hongyu Chen
Keyword(s):  
Real Time ◽  
Ligand Exchange ◽  
Au Nanoparticles ◽  
Relative Strength ◽  
Real Time Monitoring ◽  
Exchange Kinetics ◽  
Colloidal Au ◽  
Kinetics Of

We show that phenynyl ligand could readily bind to colloidal Au nanoparticles. By real-time monitoring the SERS during ligand exchange, the relative strength of phenynyls, thiols and PVP ligands, and different phenynyls were successfully ranked.

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