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What is the nephelauxetic series?
The nephelauxetic series is a list of ligands or metal ions ordered on the basis of the strength of their nephelauxetic effect. This refers to a decreasing Racah parameter (B), a measure of inter-electronic repulsion, that occurs when a free transition-metal ion forms a complex with different types of ligands.
How is nephelauxetic effect calculated?
The nephelauxetic effect / is calculated by the formula / F B/B0, where B0 F 785cmY1 [4, 5] is the Racah parameters for free Mn2+ ion. By substituting the B and B0 (as mentioned above), we find that / F 0.78.
Which has highest nephelauxetic effect?
SPECTROSCOPY OF LANTHANIDE COMPLEXES The above series in general is similar to the ligand nephelauxetic series observed in the case of d-transition metals. The greatest nephelauxetic effect has been observed in sulphides [46], cyclopentadienides [47], and oxides [48] of lanthanides.
Racah parameters were generated as a means to describe the effects of electron-electron repulsion within the metal complexes. Comparisons between tabulated free ion B and B of a coordination complex is called the nephelauxetic ratio (the effect of reducing electron-electron repulsion via ligands).
Is co High spin or low spin?
Strong-field ligands, such as CN− and CO, increase the Δ splitting and are more likely to be low-spin. Weak-field ligands, such as I− and Br− cause a smaller Δ splitting and are more likely to be high-spin.
What is chelate effect?
The chelate effect is the enhanced affinity of a chelating ligand for a metal ion compared to its monodentate ligand counterpart(s). This term comes from the Greek chelos, meaning “crab”. Tridentate ligands, which bind through three donors, can bind even more tightly than bidentate, and so on.
What is DQ value?
This factor (Dq) is actually the minimum value of ∫ (±2)*V oct (±2) d t and the values the other d wave functions are the multiples of this quantity [t should be read as tau]. Here a4 – represents mean fourth power radius of d electrons of the central metal ion (Note that 4- should be read as dash on 4).
What is racah parameter discuss the factor which affects its magnitude?
When an atom has more than one electron there will be some electrostatic repulsion between those electrons. The amount of repulsion varies from atom to atom, depending upon the number and spin of the electrons and the orbitals they occupy.
What is meant by high-spin and low spin complexes?
High-spin complexes: When crystal field splitting energy is greater than electron pairing energy, the complexes formed are high-spin complexes. ii. Low-spin complexes: When crystal field splitting energy is smaller than electron pairing energy, the complexes formed are low-spin complexes.
Is paramagnetic high-spin?
The strength of the paramagnetism of a coordination complex increases with the number of unpaired electrons; a higher-spin complex is more paramagnetic.