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Questions tagged [crystal-field-theory]

For questions relating to the electronic structure of inorganic complexes, particularly the splitting of degenerate $d$ or $f$ orbitals by the symmetry of the surrounding ligands.

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How to understand MO diagrams for cationic octahedral transition metal complexes

I am having problems understanding the construction of MO diagrams in octahedral transition metal complexes within ligand field theory (LFT) when the metal center is asumed as an cation: I am ...
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What is the magnetic moment of potassium hexacyanochromate(II)?

I calculated the magnetic moment of $\ce{K4[Cr(CN)6]}$? in the following way: $\ce{Cr^{+2}}$ has $4$ d electrons. And since $\ce{CN-}$ is a strong field ligand, the electrons will pair up in the $\...
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Fluoride anion as a strong field ligand

In the case of $\ce{[Fe(H_2O)_6]^{3+}}$ there are $5$ unpaired electrons as water acts as a weak field ligand. But instead of flouride acting as a weak field ion in the $\ce{[MnF_6]^4-}$ , why does it ...
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Bonding in Zeise's salt

I am not sure I completely understand the bonding in coordination compounds formed by donation of pi electron cloud by the ligands to the central atom. For example, consider Ziese's salt: I came ...
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1answer
270 views

Is cobalt(II) in the hexaamminecobalt(II) complex high spin or low spin?

I want to determine the electronic configuration of $\ce{Co}$ in $\ce{[Co(NH3)_6]Cl2}$ with Crystal Field Theory. I know that since the complex is octahedral, there would be degeneracy breaking and ...
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t2g orbitals in [Co(OH2)6]3+

Is the best description of the $\ce{t2g}$ orbitals in $\ce{[Co(OH2)6]^{3+}}$ bonding, antibonding, or nonbonding? My textbook says that if the complex only forms $\ce{\sigma}$ bonds, then the ...
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293 views

Why is CO ligand higher than CN- in the spectrochemical series?

I've drawn MO diagrams for both molecules and they are isoelectronic. The main difference is that $\ce{C}$ is closer in electronegativity to $\ce{N}$ than it is to $\ce{O}$ so there will be less ...
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Effect of oxidation state on d-orbital splitting

I am trying to understand the effect of oxidation state on d-orbital splitting e.g. in Iron. I understand that splitting itself is caused by the fact that different d-orbitals are positioned ...
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How does the Jahn-Teller distortion result in both elongation and compression?

Recently, I have been reading up on the Jahn-Teller effect and I have read articles and posts on it, such as What is the mathematical basis behind the Jahn-Teller effect?. However, many of these ...
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250 views

Why do NON -Transition elements exhibit variable oxidation state?

I know transition elements exhibit variable oxidation states because valence electrons are in d block and s which are very close so they have similar energies ,thus with slightly different energies ...
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Jahn Teller distortion and magnetic moments.

It is relatively well known that the discrepancy between the observed and experimental magnetic moments in the first row transition metals is attributed to spin-orbit coupling when it comes to metal ...
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767 views

Why is a [Cu(SCN)2] complex black?

I've been creating various Copper(II) complexes using different ligands and predicting their relative hues using Crystal Field Theory by using the spectrochemical series to predict the extent of d ...
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388 views

Tetragonal (z-in/z-out) in tetrahedral complexes?

Is it possible to have tetragonal distortion in tetrahedral complexes? Because distortions in octahedral complexes take place along the C4 axis to reduce the symmetry to D4h, but there is no C4 ...
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Crystal Field Theory - Operator Equivalent Methods

I am a bit confused by some of the points of operator equivalent methods in crystal field theory. I would appreciate any help I could get with any of my questions. First, I am confused as to the ...
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511 views

Why does cobalt primarily form low-spin complexes?

Why is $\ce{[Co(NH3)6]^3+}$ a low spin complex while the nickel equivalent is a high spin complex? And in general, why does cobalt have a tendency to form these low spin complexes? In "Why is ...
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Color of a coordination compound

In my class $12$ book, i'm supposed to explain the green color of solution of $\ce{[Ni(H_2O)_6]^{2+}}$ and the colorlessness of a solution of $\ce{[Ni(CN)_6]^2-}$. I tried to answer it using CFT and ...
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How does the dx2-y2 orbital bond with four ligands in square planar metal-metal complexes

I understand that the complex [Re2Cl8]2- has a bond order of 4 between the ruthenium ions. The bond comprises of sigma interactions between Dz2 orbitals, two sets of pi interactions between dxz and d ...
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426 views

Regarding Crystal Field Theory, where do the names eg and t2g come from?

So with Crystal Field Theory, a metal anion in an octahedral coordination complex has two sets of separately degenerate d orbitals--that is to say, the metal's dxy, dxz, and dxz orbitals are of a ...
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297 views

Crystal field splitting in complexes other than octahedral or tetrahedral [closed]

Is there a methodology to developing the crystal field splitting diagram for various crystal fields? I know the octahedral and tetrahedral diagrams, but if I'm asked to draw something like square ...
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Why does some compound as given in the image below change from low spin to high spin above a particular transition temperature?

Magnetic moment sudden increase at a particular temperature is explained by CFT. But why does it happen at all?
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Ionic interaction in crystal field theory

How correct is the assumption of ionic interaction between the ligands and the central metal atom in cft when many ligands do not even possess charge over them? Besides, I also referred to the ...
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384 views

Identifying a Positive or Neutral Ligand Inside Coordination Sphere?

There are some coordination compounds like $\ce{Na2[Fe(CN)5NO]}$, where ligands like $\ce{NO}$ are used which exist as both $\ce{NO+}$ (nitrosonium ion) and $\ce{NO^.}$ (neutral nitrosyl). How to ...
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Why is hexafluoridocobaltate(III) the only common high-spin cobalt(III) complex?

Almost all $\ce{Co^3+} (\mathrm{d^6})$ complexes are low spin, including $\ce{[Co(H2O)6]^3+, [Co(ox)3]^3–, [Co(NH3)6]^3+}$ and $\ce{[Co(CN)6]^3–}$. The only common high-spin cobalt(III) complex is $\...
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667 views

What's the configuration of chromium(III) in aqueous medium according to crystal field theory?

It has $\mathrm{3d^3}$ configuration, but how will we decide if they enter $\mathrm{t_{2g}}$ or $\mathrm{e_g}$ orbitals since we don't know which complex will form?
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Energies of d orbitals relative to the barycentre

Rather than referring to the energy of an isolated metal atom, the weighted mean of these two sets of perturbed orbitals $(\mathrm d_{xy}, \mathrm d_{xz}, \mathrm d_{yz}$ and $\mathrm d_{x^2 - y^2}$, $...
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Color difference among oxovanadium species

Why dioxovanadium $\ce{[VO2]+}$ is pale yellow, whereas orthovanadate $\ce{[VO4]^3-}$ is colorless? Both of them should be colorless if we ignore charge transfer for a moment, because in both cases ...
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Why do compounds form if overall energy of free ion increases according to CFT

According to crystal field theory, a free ion has certain energy and its energy increases when it is symmetrically surrounded by ligands. Now the degenerate d orbitals split into two new set of ...
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759 views

In an octahedral complex, what happens to the electrons donated by the ligand?

I am trying to understand how complexes are coloured. After some reading, I found out this was due to the d-d splitting induced by the coordinate bonds of ligands to the central metal ion. The ...
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What will happen if ligand orientation is changed?

How we came to know ligand should approach from t2g orbitals in d5 configuration for tetrahedral complexes? What will be the difference in energy if ligand approach from eg? As far as I can think, ...
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Why is anhydrous CuSO4 White while hydrated CuSO4 is Blue? (even though both have one unpaired electron)

We all know that $\ce{CuSO4.5H2O}$ is blue and it turns to $\ce{CuSO4}$ on heating which is white. I also learnt about coordination complexes and d-d transitions and how transition metal compounds are ...
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Theoretically, Which d orbital participates in sp3d and sp3d2?

This question is regarding the old way (inaccurate) $\ce{PCl5}$ and $\ce{SF6}$ are taught in elementary chemistry. In the crystal field splitting diagram for triagonal bypyramidal geometry, $\mathrm{...
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How to determine if a complex has a crystal field stabilization energy of zero?

I have encountered with the following question: The complex having zero crystal field stabilisation energy is: (A) $\ce{[Mn(H_2O)6]^3+}$ (B) $\ce{[Fe(H_2O)6]^3+}$ (C) $\ce{[Co(H_2O)6]^2+}$ (D) ...
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Why do ligands approach along the axes?

According to the Crystal Field Theory (CFT), it is given that ligands (their lone pairs) approach the central metal along the axes. When they approach, the degeneracy of the $\mathrm{d}$ orbitals is ...
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Crystal Field Splitting of d-Orbitals in Octahedral and Tetrahedral Ligand Fields

We're learning about the Crystal Field Theory (CFT, under coordination chemistry) at school now, and my teacher mentioned that the 5 d-orbitals split into orbital sets, namely the $\mathrm{t_{2g}}$ (...
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Spectrochemical Series - Latest version?

--Studying the Crystal Field Theory [under Coordination Chem.] at school now-- A book my teacher lent me [printed in 2002] has the spectrochemical series in it, and it depicts pyridine [py] as having ...
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d-orbital splittings in WS2 monolayer

The formerly degenerate $d$ orbitals of the tungsten atoms in the $\ce{WS2}$ monolayer are split into three groups: (1) $\mathrm{d}_{z^2}$, (2) $\mathrm{d}_{x^2-y^2}, \mathrm{d}_{xy}$ and (3) $\mathrm{...
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Deducing orbital degeneracy in geometries apart from octahedral or tetrahedral

How do you determine the crystal field splitting pattern when given the structure of a complex? It's quite simple for structures like octahedral or tetrahedral, but I find that the reasoning behind ...
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578 views

Clarification on absorption spectra and crystal field theory

My textbook, Chemistry: The Central Science, gives this figure to explain the purple color of the hexaaquatitanium(III) ion: Such absorption spectra are common to chemistry and biochemistry. However, ...
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What chemical properties that allow for colour exist in the dark?

Of course if there's no light around, there's no colour that you can see. On the other hand, the wall must have some property that makes it be blue. That property is still there in the dark. — ...
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Energy of orbitals under a crystal field

It is shown in octahedral crystal field splitting that both the $e_g$ orbitals have equal energy. But how can that be possible ? The $d_{x^2-y^2}$ is directed along both the axes (x and y) whereas ...
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Growing crystals that are in a magnetic field or subjected to an electric field

I know different crystals resonant at different frequencies but is it possible to grow crystal at a certain frequency. An example would be growing crystals using Epsom salt or Alum in a magnetic ...
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422 views

In crystal field theory, why do all the metal electrons enter the d orbitals and not the s orbital?

Suppose we have the complex $\ce{[Fe(H2O)6]}$. Iron has 26 electrons, and its electronic configuration is therefore $[\ce{Ar}]\,\mathrm{4s^2 3d^6}$, but in crystal-field theory, we say that the $\...
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How can the electronic structure of pentaaquanitrosyliron be explained?

The magnetic moment of $\ce{[Fe(H2O)5NO]^2+}$ is 3.87 Bohr magneton, which implies that there are 3 unpaired electrons. Since iron is in $+1$ oxidation state (due to charge transfer with nitrosyl ...
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Stability of transition metals in aqueous solution

Which is more stable in aqueous solution: $\ce{Cr^3+}$ or $\ce{Mn^3+}$? Why? My approach: $\ce{Cr^{3+}}$ should be more stable as the $\ce{3d}$ electrons will enter the $\mathrm{t_{2g}}$ orbitals. ...