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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Why is Libethenite (Cu2(OH)PO4) color green?

It is not a complex compound and the copper atom is not oxidized so I'm wondering how does its color change. The book mentioned that at favorable conditions, adding water in Copper phosphate, which is ...
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Colour of metal complexes with the same type and number of ligands

Crystal Field Theory says that because of d-orbital splitting caused by different ligands we have 2 different energy levels for d-orbitals. It also says that transition metals are coloured because ...
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Why are d(xy),d(yz) and d(xz) orbitals involved in d³s hybridisation?

Shouldn't d(x²-y²) dxy and dz² orbitals participate? Since this corressponds to the best case overlap? What factors decide the participating orbitals in hybridisation? P.S I am well versed with the ...
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713 views

Why is Ni[(PPh₃)₂Cl₂] tetrahedral?

Since PPh₃ is strong field ligand and, the famous Wilkinson's catalyst, which also possess this ligand is square planar, then what makes the above complex tetrahedral?
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Changing of UV-Vis peak absorption after heating Ni(en)2(NO2)2

(c) The trans-isomer of $\ce{Ni(en)2(NO2)2}$ D is red $(λ_\mathrm{max} = \pu{500 nm}).$ It can be heated to give a new trans-isomer E, which is violet $(λ_\mathrm{max} = \pu{560 nm}).$ Assume that, ...
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Applying Ligand Field Theory, How Can The Color Of Transition Complex Ions Be Explained/Represented?

1. To my understanding, Crystal Field Theory allows for an explanation for the colors of transition metal complex ions due to the d-d transitions which occur. This transition ∆o, is from the t2g ...
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98 views

Derivation of t2g eg splitting in octahedral field

I am trying to make the derivation of the d orbitals splitting under an octahedral field but I am kind of at a loss and don't know of any literature that can provide a more introductory level of this ...
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148 views

Magnetic moment from given CFSE value

Spin magnetic moment of a octahedral complex having CFSE = $– 0.8∆$ and surrounded by weak field ligands can be: A. $\sqrt{15} \space \mu_B$ B. $\sqrt{8} \space \mu_B$ C. (A) & (B) ...
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79 views

Why do some ions form tetrahedral complexes more readily than others? [closed]

Why does Co$^{2+}$ readily form tetrahedral complexes such as [CoCl$_4$]$^{2-}$, whereas Fe$^{2+}$ usually forms octahedral complexes?
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41 views

Spin state change during crystallisation for [NiCl2(PPh3)2]

$\ce{NiCl2(PPh3)2}$ is a complex that is borderline between tetrahedral(high spin) and square planar(no unpaired electron, high splitting parameter) because $\ce{Cl-}$ is a weak field ligand and $\ce{...
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276 views

Electronic configuration of d5-d-10 in terms of t2g and eg in an octahedral field when delta O is smaller than pairing energy?

As per the Crystal Field Theory, d4 splits into t2g3 and eg1 when delta 0 < Pairing energy. What about d5, d6 and so in the same case? Does the fifth, sixth... electrons enter the t2g or eg ...
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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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222 views

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
1k 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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173 views

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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1answer
1k 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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338 views

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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408 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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233 views

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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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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469 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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253 views

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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956 views

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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1answer
359 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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244 views

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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1answer
577 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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1answer
2k views

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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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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320 views

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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1answer
85 views

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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996 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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1answer
1k views

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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1answer
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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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60 views

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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496 views

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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290 views

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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1answer
702 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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129 views

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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139 views

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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1k views

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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486 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 ...