What is ligand: Definition and 16 Discussions

In coordination chemistry, a ligand is an ion or molecule (functional group) that binds to a central metal atom to form a coordination complex. The bonding with the metal generally involves formal donation of one or more of the ligand's electron pairs, often through Lewis bases. The nature of metal–ligand bonding can range from covalent to ionic. Furthermore, the metal–ligand bond order can range from one to three. Ligands are viewed as Lewis bases, although rare cases are known to involve Lewis acidic "ligands".Metals and metalloids are bound to ligands in almost all circumstances, although gaseous "naked" metal ions can be generated in a high vacuum. Ligands in a complex dictate the reactivity of the central atom, including ligand substitution rates, the reactivity of the ligands themselves, and redox. Ligand selection requires critical consideration in many practical areas, including bioinorganic and medicinal chemistry, homogeneous catalysis, and environmental chemistry.
Ligands are classified in many ways, including: charge, size (bulk), the identity of the coordinating atom(s), and the number of electrons donated to the metal (denticity or hapticity). The size of a ligand is indicated by its cone angle.

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  1. matthieu1973

    Designing best theoretical sax/clarinet mouthpiece ligand

    Hey to all.. I am in the process of designing a ligand for a clarinet mouthpiece for my own use created only out of string material (braided kevlar). For those uninformed (like me a few weeks ago) saxophone/clarinets are instruments where the vibration of the standing wave through the...
  2. Wrichik Basu

    Ammonia is a strong or weak field ligand?

    Ammonia is present in the spectrochemical series near the middle, just after water. Is it a strong field ligand, or a weak field ligand? Also, take into consideration the complex ##[Ni(NH_3)_4 Cl_2]##. Chloride ion is towards the left end of the spectrochemical series which means it is a weak...
  3. ReidMerrill

    Ligand Field Strength and UV absorbance

    I have a lab report for an experiment in which we used ion exchange chromatography to separate three Chromium complexes, CrCl2(OH2)4+, CrCl(OH2)52+, and Cr(OH2)63+ We used a UV vis to find the absorbance of each compound and used that to calculate the mole fraction of each ion in a mixture. One...
  4. K

    Ligand field theory and CuCl2 colors

    Copper (ii) chloride is a light brown solid, which slowly absorbs moisture to form a blue-green dihydrate. According to ligand field theory, water is a stronger field ligand than chloride. As a result, the dihydrate form should have a larger d orbital splitting than the anhydrous form. Thus...
  5. G

    Ligand Charge Density: PEG-COOH vs. PEG-OH

    I want to exchange my Au-citrate nanoparticle with two kinds of ligands :PEG-COOH and PEG-OH. Which one is suppose to have more anionic charge density.
  6. L

    Ligand field theory and f orbitals in magnetism

    I've been introduced to ligand-field theory lately and was then wondering what roles f orbitals play in the magnetic properties of elements and alloys. Apparently f orbitals behave oddly in that they hybridize in weird ways because they're so large and that the crystal field actually affects the...
  7. Y

    What are the best ligands for PbS quantum dots in solar cell applications?

    Hi everyone, I'm working with quantum dot (PbS). However, I'm actually not a chemist, so could anyone help me to address some issues regarding quantum dots especially related to ligand exchange process. My questions are: 1. anyone can address about what kind of functionality (e.g: thiol...
  8. J

    Ligand Exchange - are they reversible?

    Are ALL ligand exchange reactions reversible? Therefore, if the Kstab of one complex is LESS than that of the other complex, would it ONLY be possible to form the LESS stable complex by 'flooding' the mixture with the appropriate ion. (these values are not real but they illustrate what I...
  9. C

    Ligand field stabilization energies, is it correct to say

    the following?: low-spin d5 metal. Energy = -2Δ -4K (where K is exchange energy. i,e. minimization of energy due to parallel spins) low-spin d6 metal. Energy = -1.6Δ -3K Therefore: energy needed to add an electron = ΔE= 0.4Δ + K Is that correct? maybe I should be talking about...
  10. Ahmed Abdullah

    What enables cells to respond to changes in the concentration of a signaling ligand ?

    "In chemical signaling, adaptation enables cells to respond to changes in the concentration of a signaling ligand (rather than to the absolute concentration of the ligand) over a very wide range of ligand concentrations. The general principle is one of a negative feedback that operates with a...
  11. C

    Naming monodentate ligand complexes

    Hi guys, i know how to name monodentate ligand complexes but there is a particular one that my textbook and teacher's notes is quite the opposite, its regarding the fac and mer isomer. for a Ma3b3 structure, a fac forms a face and a mer have the ligands in meridian position, but for these...
  12. K

    After a ligand bonds to a receptor through intermolecular forces

    After a ligand bonds to a receptor through intermolecular forces, how is it unbound and what happens to it after it is?
  13. Q

    What is the effect of temperature on ligand integrin dimerization?

    Homework Statement 3 different RGD-containing ligands (including Integrilin) are used to form receptor-ligand complexes, and measured dimerization of ligand-bound receptors as a fuction of temperature in the range 20-40C using a variety of methods. The 3 ligands are cHArGd, cRGD, and...
  14. N

    Inorganic Ligand Naming Question

    Naming the complexes with two different types of ligands confuse me. How do you tell which ligand to include first in the name? Which ligand do you write first in the brackets? Thanks for anyhelp
  15. E

    Ligand substitution & first row transition metal complexes

    anybody know what the primary mode of ligand substitution for first row octahedral transition metal complexes?