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This discussion is being held at Talk:Ligand (biochemistry). Single word comment moved there. Walkerma 02:49, 17 December 2005 (UTC)
The word ligand is used very differently in biochemistry and in chemistry. It is important to keep this as a branch point. anyone searching for ligand would come in here and click on the biochemistry side or the inorganic chemistry side. They can be directed to the right place. This should not be moved permanently to biochemistry {ashoka.samuelson@gmail.com}
As a chemistry undergraduate I found the ligand (chemistry) page very clear and extreamly useful when researching for EDTA titration information. Having looked at the ligand (biochemistry) article I think I would have found it confusing if the two had been merged. I am happy as things are - with a link between the pages. Thanks for the excellent service. (contributed by 86.132.215.214)
Since the consensus is to keep these articles apart, I think the merge proposal should be removed. -- Scot t 12:50, 25 March 2006 (UTC)
The charge on the central atom (called the oxidation number) constrains the number of ligands that may be bonded because each type of ligand donates a characteristic number of electrons, and there is a requirement for overall neutrality. This sentence was removed. It is strictly true that neutrality is required for a molecule overall, but the complex may be a complex ion (positive or negative) and most transition metals bond octahedrally regardless of the charges of the ligands or their own oxidation states. I see what the author of the above sentence was getting at, but how could it be better said? Srnec 21:59, 19 April 2006 (UTC)
I moved a lot of parts from Complex (chemistry), which were merely descriptions of ligands, to this page, I do believe that some could serve a function here, but there is quite some redundancy. I will try to clean-up the mess later (but feel free to mess around with it), for now I am busy with Complex (chemistry). -- Dirk Beetstra 21:24, 16 May 2006 (UTC) (hume nahi pata kuch , paise kamane ko likhdiya bas))
Smokefoot, I fail to understand the rationale for most (perhaps all) of your most recent edits. For example:
Finally, the sections you want to delete are there so thhhhat someone finds them when they come to this article. They are not in-depth. They are here for comprehensiveness (so that nothing of importance is completely left out, leaving the reader to search it out some more). Srnec 00:15, 18 May 2006 (UTC)
Take a whack at fixing it up! We can work together as I have done with others.-- Smokefoot 02:36, 18 May 2006 (UTC)
I have moved some things to Complex (chemistry) (reactions, geometry (which was already available on the other side), isomerism (needs cleanup on the other side). I still have a bit of trouble with strong/weak field ligands. The spectroscopy belongs on the other side, where the strength has reason to be on this end... I will edit on when I have time today. About the large macrocycles, take care not to write it in a 'by definition' way, that a ligand is multidentate does not by definition mean that it will bind better than the loose ligands (I have seen some tridentate 'ligands' around, which just seem to refuse in all cases to act as a ligand. There is more to it than multidenticity, the 'hardness' of the ligand has to match the metal, the geometries have to be OK (of the free orbitals on the metal in combination with how the glove fits the hand), and some metals have a tendency to prefer certain symmetries. -- Dirk Beetstra 07:17, 18 May 2006 (UTC)
==Denticity vs. hapticity== lamborghini
Is the following sentence correct:
Srnec 17:07, 18 May 2006 (UTC)
So the sentence is correct? Good. Also, to answer a question above, the lists are convenient separate so that people can identify ligands based on different properties, or find a ligand of a given property. Srnec 03:18, 19 May 2006 (UTC)
== Database problem == bmw Seems that the page came true, removed the dump again (illegible anyway) -- Dirk Beetstra 22:27, 24 May 2006 (UTC)
I have put the remainder of the ligands in a table, which is far from complete, so I have added an 'expand' to it. Things that need to be done:
Hope you can help. Cheers! -- Dirk Beetstra 13:17, 29 May 2006 (UTC)
There are now two statements above the page, where the word ligand is used in another sense than the inorganic way, should 'ligand' not be a disambiguation page, pointing towards ligand (biochemistry), ligand (pharmacology) and ligand (chemistry) (the latter should then contain the information now on ligand)?? -- Dirk Beetstra 09:03, 3 June 2006 (UTC)
The current article (July 9, '06) states: "In chemistry, a ligand is an atom, ion, or molecule (see also: functional group) that generally donates one or more of its electrons through a coordinate covalent bond to, or shares its electrons through a covalent bond with one or more central atoms or ions (these ligands act as a Lewis base. Fewer examples exist where a molecule can be described as a ligand that accepts electrons from a Lewis base (hence, the ligand acts as a Lewis acid)." Whether we like it or not, the second sentence contradicts the first. We can't begin the article by saying in effect " ligands are Lewis bases, unless they are Lewis acids, and oh, sometimes they donate one electron to make covalent bonds" - which is what it currently says. I dont have any great ideas about how to resolve the current wide-open definition.
My recommendation would be to admit that the nomenclature is imperfect but that generally, ligands are considered to be the Lewis base component of an adduct. Thus BF4- has four fluoride (vs fluorine) ligands. -- Smokefoot 18:12, 8 July 2006 (UTC)
Note: The entries in the table are sorted by field strength, binding through the stated atom (i.e. as a terminal ligand), the 'strength' of the ligand changes when the ligand binds in an alternative binding mode (e.g. when it bridges between metals) or when the conformation of the ligand gets distorted (e.g. a linear ligand that is forced through steric interactions to bind in a non-linear fashion). hellow
hellow = vandalism right? —The preceding unsigned comment was added by 144.136.38.19 ( talk) 09:36, 19 February 2007 (UTC).
So whats the goal with the tables - list every ligand? As we known virtuallyevery organic compound is a ligand under the right circumstances. If one excludes agostic complexes, then every amine, phosphine, ether, alkene, arene, heterocycle... Some thought might be given to a classification scheme (perhaps based on donor atoms and denticity and branched vs linear) otherwise this article collapses under the weight of minutia. The second table is entitled "Other general (should be 'generally') encountered ligands (alphabetical)" Note the word "general." IMHO.-- Smokefoot ( talk) 15:04, 18 November 2007 (UTC)
Hmm... if there were a list, common ligand classes like phosphines, amines, porphyrins should be included. There should probably be mention of specialized ligand classes like scorpionates too. Other common specific ligands like COD, acac, Cp/Cp'/Cp*, DPPM/E/P/F too. At least, this is what is notable from my POV. But if we end up with an unmaintainable list, perhaps we should describe some common classes in the text instead? Perhaps we can use sortable tables to make it more usable? --
Rifleman 82 (
talk)
15:41, 18 November 2007 (UTC)
Can we have another image of a more conventional ligand? The one posted was obscure. The legend was incidentally ungrammatical and misspelled. Tmangray ( talk) 16:51, 2 April 2008 (UTC)
Metal ions bound to strong-field ligands follow the Aufbau principle, whereas complexes bound to weak-field ligands follow Hund's rule.
According to its own article the Aufbau principle seems to include Hund's rule, so what is meant by "whereas" (or by Aufbau principle and Hund's rule) here? —Preceding unsigned comment added by 194.81.223.66 ( talk) 09:18, 18 August 2008 (UTC)
There is no mention of L-type and X-type, their distinction and meaning. While a trivial distinction that falls out of the electron counting, these are terms in use and I wonder if they don't warrant at least a mention somewhere within Wikipedia. Are there any thoughts? Gaedheal ( talk) 15:05, 29 October 2009 (UTC)
""Ligand, in chemistry, is any atom or molecule attached to a central atom, usually a metallic element, in a coordination or complex compound. The atoms and molecules used as ligands are almost always those that are capable of functioning as the electron-pair donor in the electron-pair bond (a coordinate covalent bond) formed with the metal atom.
Examples of common ligands are the neutral molecules water (H2O), ammonia (NH3), and carbon monoxide (CO) and the anions cyanide (CN-), chloride (Cl-), and hydroxide (OH-). Occasionally, ligands can be cations (e.g., NO+, N2H5+) and electron-pair acceptors. The ligands in a given complex may be identical, as the CO ligands in Fe(CO)5 and the H2O ligands in [Ni(H2O)6]2+, or different, as the CO and NO ligands in Co(CO)3(NO).
A metal ion in solution does not exist in isolation, but in combination with ligands (such as solvent molecules or simple ions) or chelating groups, giving rise to complex ions or coordination compounds. These complexes contain a central atom or ion, often a transition metal, and a cluster of ions or neutral molecules surrounding it.
Ligands are ions or neutral molecules that bond to a central metal atom or ion. Ligands act as Lewis bases (electron pair donors), and the central atom acts as a Lewis acid (electron pair acceptor). Ligands have at least one donor atom with an electron pair used to form covalent bonds with the central atom.
The term ligand come from the latin word ligare (which meaning to bind) was first used by Alfred Stock in 1916 in relation to silicon chemistry.
Ligands can be anions, cations, or neutral molecules. Ligands can be further characterized as monodentate, bidentate, tridentate etc. where the concept of teeth (dent) is introduced, hence the idea of bite angle etc.
Attachment of the ligand to the metal may be through a single atom, in which case it is called a monodentate ligand, or through two or more atoms, in which case it is called a didentate or polydentate ligand."" 49.185.137.168 ( talk) 13:52, 15 May 2022 (UTC)
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