ChemInform Abstract: Solution Dynamics of the Reversible Carbonyl-Phosphorus Ligand Exchange in (OC)4Mo(μ-PEt2)2Mo(CO)4: Kinetic Parameters as a Measure of the Relative Steric Hindrance of Phosphines and Phosphites.

1986 ◽  
Vol 17 (22) ◽  
Author(s):  
M. BASATO
Keyword(s):  
Kinetic Parameters ◽  
Steric Hindrance ◽  
Ligand Exchange ◽  
Solution Dynamics

scholarly journals Chemically Fueled Transient Geometry Changes in Diphenic Acids

2020 ◽  
Author(s):  
Isuru Jayalath ◽  
Hehe Wang ◽  
Georgia Mantel ◽  
Lasith S. Kariyawasam ◽  
Scott Hartley
Keyword(s):  
Quantitative Analysis ◽  
Kinetic Parameters ◽  
Dihedral Angle ◽  
Steric Hindrance ◽  
Molecular Geometry ◽  
Torsional Angle ◽  
Fuel Treatment ◽  
Simple Mechanism ◽  
Ethylcarbodiimide Hydrochloride ◽  
Biochemical Systems

Transient changes in molecular geometry are key to the function of many important biochemical systems. Here, we show that diphenic acids undergo out-of-equilibrium changes in dihedral angle when reacted with a carbodiimide chemical fuel. Treatment of appropriately functionalized diphenic acids with EDC (<i>N</i>-(3-dimethylaminopropyl)-<i>N</i>′-ethylcarbodiimide hydrochloride) yields the corresponding diphenic anhydrides, reducing the torsional angle about the biaryl bond by approximately 45°, regardless of substitution. In the absence of steric resistance, the reaction is well-described by a simple mechanism; the resulting kinetic parameters can be used to derive important properties of the system, such as yields and lifetimes. The reaction tolerates steric hindrance ortho to the biaryl bond, although the competing formation of (transient) byproducts complicates quantitative analysis.

Polymérisation du norbornène par des amorceurs au ruthénium. Etude cinétique de la réaction

1980 ◽  
Vol 58 (24) ◽  
pp. 2813-2818 ◽  
Author(s):  
Charles Tanielian ◽  
Alain Kiennemann ◽  
Temel Ösparpucu
Keyword(s):  
Kinetic Parameters ◽  
Homogeneous Catalysis ◽  
Reaction Mechanisms ◽  
Ligand Exchange ◽  
Alcohol Concentration ◽  
Zero Order ◽  
Slow Step ◽  
Variable Order ◽  
First Order ◽  
Initiation Step

The kinetic parameters for the polymerisation reaction of norbornene with RuCl3•3H2O, and RuCl2(PΦ3)3 using homogeneous catalysis have been determined (first-order with respect to two initiators, zero-order with respect to the monomer with RuCl3•3H2O, and variable order with RuCl2(PΦ3)3: Ea 6.2 kcal/mol for RuCl2(PΦ3)3 and 22.8 for RuCl3•3H2O) and leads us to propose different reaction mechanisms for the polymerisation starting from the two initiators, at least for the initiation step. With RuCl2(PΦ3)3 the slow step of the reaction is the metathesis whereas with RuCl3•3H2O the slow step is a ligand exchange at the initiator involving solvent (alcohol) by a dissociative or associative mechanism. This slow step is confirmed by a study of varying alcohol concentration and initiator aging. [Journal translation]

A phosphorus-31 magnetic resonance study of ligand exchange on tetrakis(hexamethylphosphoramide)zinc(II) ion

1980 ◽  
Vol 33 (12) ◽  
pp. 2621 ◽  
Author(s):  
MN Tkaczuk ◽  
SF Lincoln
Keyword(s):  
Magnetic Resonance ◽  
Kinetic Parameters ◽  
Time Scale ◽  
Ligand Exchange ◽  
Exchange Process ◽  
Magnetic Resonance Study ◽  
Fast Exchange

The rate of the associative ligand exchange process on tetrakis (hexamethylphosphoramide)zinc(II) ion in CD2Cl2 solution, determined by 31P n.m.r. spectroscopy, is given by: ������������������� rate = 4k2[O=P(Nme2)3][Zn(O=P(NMe2)3)42+] The characteristic kinetic parameters are: k2(240 K) 304�17 dm3 mol-1 s-1, ΔH2‡ 22.7�0.9 kJ mol-1, and ΔS2‡ -101�4 J K-1 mol-1. ��� The preparations of [Zn(O=P(NMe2)3)4](ClO4)2, [Zn(O=P(OMe)3)5] (ClO4)2 and [Zn {O=P(Me)-(OMe)2}5](ClO4)2 are reported. The rate of ligand exchange upon the last two species was found to be in the fast-exchange limit of the n.m.r. time scale.

Controlled Steric Hindrance Enables Efficient Ligand Exchange for Stable, Infrared-Bandgap Quantum Dot Inks

2019 ◽  
Vol 4 (6) ◽  
pp. 1225-1230 ◽  
Author(s):  
Mengxia Liu ◽  
Fanglin Che ◽  
Bin Sun ◽  
Oleksandr Voznyy ◽  
Andrew Proppe ◽  
...  
Keyword(s):  
Quantum Dot ◽  
Steric Hindrance ◽  
Ligand Exchange

pH-Dependent solution dynamics of a manganese(ii) polyoxometalate, [Mn4(H2O)2(P2W15O56)2]16−, and [Mn(H2O)6]2+

2015 ◽  
Vol 44 (44) ◽  
pp. 19068-19071 ◽  
Author(s):  
Rupali Sharma ◽  
Jie Zhang ◽  
C. André Ohlin
Keyword(s):  
Exchange Rate ◽  
Ligand Exchange ◽  
Water Ligand ◽  
Solution Dynamics ◽  
Order Of Magnitude ◽  
Ph Dependent

The NMR-determined pH-dependent water–ligand exchange rate of a Mn(ii)-polyoxometalate varies by more than an order of magnitude, in contrast with those of a hexa-aqua ion.

scholarly journals Axial Ligand Exchange of N-heterocyclic Cobalt(III) Schiff Base Complexes: Molecular Structure and NMR Solution Dynamics

2013 ◽  
Vol 52 (2) ◽  
pp. 1069-1076 ◽  
Author(s):  
Lisa M. Manus ◽  
Robert J. Holbrook ◽  
Tulay A. Atesin ◽  
Marie C. Heffern ◽  
Allison S. Harney ◽  
...  
Keyword(s):  
Molecular Structure ◽  
Schiff Base ◽  
Ligand Exchange ◽  
Axial Ligand ◽  
Schiff Base Complexes ◽  
Solution Dynamics

scholarly journals Chemically Fueled Transient Geometry Changes in Diphenic Acids

2020 ◽  
Author(s):  
Isuru Jayalath ◽  
Hehe Wang ◽  
Georgia Mantel ◽  
Lasith S. Kariyawasam ◽  
Scott Hartley
Keyword(s):  
Quantitative Analysis ◽  
Kinetic Parameters ◽  
Dihedral Angle ◽  
Steric Hindrance ◽  
Molecular Geometry ◽  
Torsional Angle ◽  
Fuel Treatment ◽  
Simple Mechanism ◽  
Ethylcarbodiimide Hydrochloride ◽  
Biochemical Systems

Transient changes in molecular geometry are key to the function of many important biochemical systems. Here, we show that diphenic acids undergo out-of-equilibrium changes in dihedral angle when reacted with a carbodiimide chemical fuel. Treatment of appropriately functionalized diphenic acids with EDC (<i>N</i>-(3-dimethylaminopropyl)-<i>N</i>′-ethylcarbodiimide hydrochloride) yields the corresponding diphenic anhydrides, reducing the torsional angle about the biaryl bond by approximately 45°, regardless of substitution. In the absence of steric resistance, the reaction is well-described by a simple mechanism; the resulting kinetic parameters can be used to derive important properties of the system, such as yields and lifetimes. The reaction tolerates steric hindrance ortho to the biaryl bond, although the competing formation of (transient) byproducts complicates quantitative analysis.

Sign in / Sign up

Export Citation Format

Share Document