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Nilanjan Bhowmick AIR 3, CSIR NET (Earth Science)
- IIT JAM
- Chemistry (CY)
When nh3 act as strong and week field legand
when NH3 act as strong and week field legand???????????????
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Dinesh khalmaniya 1 Best Answer
NH3 is a ligand with medium field strength. This is because its sigma donating capability is not very strong, and more importantly, it is neither a pi acceptor non a pi donor. That is why NH3 ligand is located at middle of the “Spectrochemical Series” for ligand but nature of ligand depends on the central atom whether it is 3d or 4d,5d and oxidation state whether it is +3 or more and electronic configuration. So always check the nature of complex so we can decide nature of any ligand
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A really important thing you have to understand here is that; The strength of a ligand actually depends upon the metal atom to which it is coordinated to. For eg; Cl- is considered as a weak ligand generally. But if you consider the complex [PtCl4]2- here Cl acts as a strong field ligand and causes e- pairing in Pt2+. This is mainly because of the large size of Pt atom.And for this reason,this complex is square planar and not tetrahedral. But to an extent,the strength of a ligand can be found out relating to its electronegativity.If a species is highly electronegative it has less tendency to donate e-s and thus is a weak field ligand.But still it is not completely acceptable as seen in the above anomaly. Being lewis bases(those who donate electrons) the ligands with less electronegativity will be stronger. Therefore, in general halogen or oxygen donors (eg-F-,Cl-,Br-,H2O)are weak field ligands and the ones in which carbon or nitrogen atom is the donor (eg-CN-,CO,NH3) are strong field ligands. After knowing this i highly recommend you read an article on crystal field theory, after which you will be able to determine whether the the ligands will form high spin or low spin complexes. Strong field and weak field ligands are semi-empirical concepts from crystal field theory.In short, weak field ligands (e.g. F-, Cl-, OH-, H2O) will result in lower splitting of the d-orbitals of the metal in the center of a complex, while strong field ligands (e.g. NH3, CN-, NO+, CO) will result in larger splitting. Wether a ligand produces a "strong" or a "weak" field was initially determined experimentally, which resulted in the so-called spectrochemical series, which lists ligands accor
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Amol ashok pawar
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It depends on the central atom , cordination number , oxidation state. If central atom is of 3d series — If cordination number is 6 (octahedral) and having +2 oxidation state then it is weak ligand and in +3 oxidation state it is strong ligand.If cordination number is 4 (tetrahedral) then it is weak ligand.
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Suman Kumar
What determines a ligand weak or strong ? Metal as well as ligand which makes the ligand strong. 3d Metal in +3 oxidation state Nh3 act as strong ligand. for 4d & 5d it is a strong ligand.