Topic
Ligand
About: Ligand is a research topic. Over the lifetime, 67732 publications have been published within this topic receiving 1359684 citations. The topic is also known as: complexing agent & ligands.
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TL;DR: In this article, a ligand electrochemical parameter, El (L), is described to generate a series which may be used to predict M(n)/M(n-1) redox potentials by assuming that all ligand contributions are additive.
Abstract: : A ligand electrochemical parameter, El (L), is described to generate a series which may be used to predict M(n)/M(n-1( redox potentials by assuming that all ligand contributions are additive. In this fashion it performs a similar purpose to the Dq parameter in electronic spectroscopy. The parameter is defined as 1/6 that of the Ru(III)/Ru(II) potential for species RuL6 in acetontrile. The El(L) values for over 200 ligands are presented and the model is tested over a wide range of coordination complexes and organometallic species. The redox potential of a M(n)/M(n-1) couple is defined to be equal to:- E(calc) = f Sigma EL (L) + c. The values of f and C, which are tabulated, depend upon the metal and redox couple, and upon spin state and stereochemistry, but, in organic solvents, are generally insensitive to the net charge of the species. Consideration is given to synergism, the potentials of isomeric species, and the situations where the ligand additivity model is expected to fail. In this initial study, the redox couples are restricted almost exclusively to those involving the loss or addition of an electron to the tzg (in Oh) sub-level.
832 citations
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TL;DR: In this paper, the authors highlight the use of non-innocent redox active ligands in catalysis and highlight four main application strategies of redox-active ligands: oxidation/reduction of the ligand to tune the electronic properties (i.e., Lewis acidity/basicity) of the metal.
Abstract: In this (tutorial overview) perspective we highlight the use of “redox non-innocent” ligands in catalysis. Two main types of reactivity in which the redox non-innocent ligand is involved can be specified: (A) The redox active ligand participates in the catalytic cycle only by accepting/donating electrons, and (B) the ligand actively participates in the formation/breaking of substrate covalent bonds. On the basis of these two types of behavior, four main application strategies of redox-active ligands in catalysis can be distinguished: The first strategy (I) involves oxidation/reduction of the ligand to tune the electronic properties (i.e., Lewis acidity/basicity) of the metal. In the second approach (II) the ligand is used as an electron reservoir. This allows multiple-electron transformations for metal complexes that are reluctant to such transformations otherwise (e.g., because the metal would need to accommodate an uncommon, high-energy oxidation state). This includes examples of (first row) transition ...
822 citations
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06 Nov 1972
TL;DR: In this article, the authors present a method for detecting the presence of a specific orGANIC material by employing a MODI-SPECIFIC for one or a group of objects (HEREINAFTER this articleERRED AS TO "LIGANDS") and binding an ENZYME to the LIGAND or LIGANF.
Abstract: NOVEL BIOLOGICAL ASSAY METHOD FOR DETERMINING THE PRESENCE OF A SPECIFIC ORGANIC MATERIAL BY EMPLOYING A MODI-SPECIFIC FOR ONE OR A GROUP OF MATERIALS (HEREINAFTER REFERRED AS TO "LIGANDS") AND BINDING AN ENZYME TO THE LIGAND OR LIGANF. D C UNTERFEIT TO PROVIDE AN "ENZYME-BOUNDLIGAND OR LIGANG COUNTERFEIT TO PROVIDE AN "ENZYME-BOUNDLIGAND," AN EXTREMELY SENSITIVE METHOD IS PROVIDED FOR ASSAYING FOR LIGANDS. THE RECEPTOR WHEN BOUND TO THE ENZYME-BOUND-LIGAND SUBSTANTIALLY INHIBITS ENZYMATIC ACTIVITY, PROVIDING FOR DIFFERENT CATALYTIC EFFICIENCIES OF ENZYME-BOUND-LIGAND AND ENZYME-BOUND-LIGAND COMBINED WITH RECEPTOR. THE RECEPTOR, LIGAND AND ENZYME-BOUND-LIGAND ARE COMBINED IN AN ARBITRARY ORDER AND THE EFFECT OF THE PRESENCE OF LIGAND ON ENZYMATIC ACTIVITY DETERMINED. VARIOUS PROTOCOLS MAY BE USED FOR ASSAYING FOR ENNZYMATIC ACTIVITY AND RELATING TO THE RESULT TO THE AMOUNT OF LIGAND PRESENT.
812 citations
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TL;DR: In this article, the dynamics and mechanism of this reaction were probed by determining its kinetic order and final equilibrium position relative to incoming (R‘S) and initial (RS) protecting thiolate ligands.
Abstract: Monolayer-protected gold clusters (Au MPCs) are stable, easily synthesized, organic solvent-soluble, nanoscale materials MPCs with protecting monolayers composed of alkanethiolate ligands (RS) can be functionalized (R‘S) by ligand place-exchange reactions, ie, x(R‘SH) + (RS)mMPC → x(RSH) + (R‘S)m(RS)m-xMPC, where x is the number of ligands place-exchanged (1 to 108) and m is the original number (ca 108) of alkanethiolate ligands per Au314 cluster The dynamics and mechanism of this reaction were probed by determining its kinetic order and final equilibrium position relative to incoming (R‘S) and initial (RS) protecting thiolate ligands The reactions were characterized by 1H NMR and IR spectroscopy, and the dispersity of place-exchange reaction products was preliminarily inspected by chromatography The results of these experiments show that ligand exchange is an associative reaction and that the displaced thiolate becomes a thiol solution product Disulfides and oxidized sulfur species are not involv
804 citations
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TL;DR: This review presents the development of a more general method to determine the steric parameter of organometallic ligands and two case studies are presented: the tertiary phosphines and the N-heterocyclic carbenes.
798 citations