Questions tagged [ligand-field-theory]

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How to explain oxidizing power from Molecular Orbital Theory

I am trying to explain the oxidizing property of $\ce{Fe^3+}$ in $\ce{H2O}$ and $\ce{CN^-}$ which is $\ce{[Fe(H2O)6]^3+}$ and $\ce{[Fe(CN)6]^3-}$. The electrochemical reactions along with their ...
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Why does the nitrito ligand have a higher Δo than water in the spectrochemical series?

I collected some data to determine the value of $\Delta_\text{o}$ for a some transition metal complexes (attached) and I'm very confused as to why $\Delta_\text{o}$ for the $\ce{ONO-}$ ligand is ...
ajk's user avatar
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3 votes
1 answer
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Deriving population of $t_{2g}$ orbitals in transition metal oxides

I have recently studied ligand field theory but there is one thing I do not understand. Consider an octaedral geometry of ligands around a transition metal with a $t_{2g}$ - $e_g$ splitting of atomic $...
Matteo's user avatar
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When relaxing the strong field interaction, the (t2g)^2 configuration splits into 4 states. What is the symbolic configuration of the Eg state?

When relaxing the infinitely strong field, the electrons start to feel one another's presence. They will, therefore, give rise to sets of states such as T1g, T2g... for the (t2g)^2 initial ...
Viliam Philippe Frano's user avatar
1 vote
1 answer
396 views

Which is better ligand, PH3 or PF3?

It confuses me that many researches pointed out different results about phosphine ligands properties (σ-donor and π-acceptor). Since both phosphine $\ce{PH3}$ and phosphorus trifluoride $\ce{PF3}$ ...
Shira's user avatar
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1 answer
111 views

How to find the ligand field splitting of d orbitals in a square planar complex?

I am working with a Iron square planar complex with $\ce{NH2-}$ and $\ce{OH-}$ ligands having cis and trans conformation. My question is how to theoretically/computationally calculate the ligand filed ...
Harshdeep Chhabra's user avatar
6 votes
1 answer
378 views

Why is there no neutral [Cr(OC)6] or anionic [Fe(NC)6] - isomers of cyanide and carbonyl complexes?

I was just reading about linkage isomerism, that usually arise due to the fact that some ligands are ambidentate (i.e. $\ce{SCN}$ and $\ce{NCS}$). I then think to myself, considering only the ligand ...
Tensor's user avatar
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Why is anhydrous trans-Bis(glycinato)copper(II) more stable than it's cis isomer?

As is shown in Ref.1, the trans isomer is much more stable, at least at molecular level. Based on the crystal structural data from Ref.2 and atomic radii of O and N from wikipedia and some little ...
RTChou's user avatar
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-2 votes
1 answer
110 views

UV absorbance titration to determine binding stoichiometry

I previously posted a question but I think I did not explain correctly. I want to construct a Job plot using UV-Vis titration to find binding stoichiometry. I have 20uM of ligand solution and 20uM of ...
dojodna's user avatar
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Can halide be a sigma donor?

When I took inorganic classes, I was told that halide is a pi donor. Assume I am using metal hexahalide why I can't put the $p_z$ orbital of the halides directing to the metal centre? With that halide ...
some one's user avatar
3 votes
1 answer
147 views

Assigning structure based on EPR spectroscopy

When given two copper(II) complexes - bis(N-3-chlorophenyl-salicydenaminato)copper(II) and bis(N-3-methylphenyl-salicydenaminato)copper(II) - how can you predict their EPR spectrum and hence their g ...
qwerty09's user avatar
-1 votes
1 answer
339 views

Why are electrons paired up in hexaaquacobalt(III)?

I know water is in the middle of the spectrochemical series generally being the differentiator between the weak field and strong field ligands. I have generally seen water being a weak field ligand, ...
Rudransh Sinha's user avatar
4 votes
1 answer
887 views

Why aluminum does not form ammonia complex ion?

I learned in my textbook that zinc forms more stable complex ion with NH3 than OH- because NH3 has only one lone pair and that makes repulsion between d orbital electron in zinc and lone pair electron ...
satoru kurita's user avatar
-1 votes
1 answer
321 views

Why does low spin character predominate in hexafluoronickelate(IV)?

According to my book there are no unpaired electrons in $\ce{NiF6^2-}$. However, that should not be the case since fluoride is a weak field ligand. Why does hexafluoronickelate(IV) behave as a low ...
amspsingh04's user avatar
0 votes
0 answers
66 views

Crystal Field Splitting Energy - Tetrachlorocuprate and Tetrachlorocobaltate

I'm a high schooler from India and it's my first time on this stack exchange. I was wondering why the crystal field splitting energy of tetrachlorocuprate differs so much from tetrachlorocobaltate. ...
chuffyduffy's user avatar
2 votes
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191 views

Why are ligand orbitals always lower in energy than the metal orbitals in the ligand field theory?

The below image has been used to represent the ligand field theory for transition metals: (Source: https://chemed.chem.purdue.edu/genchem/topicreview/bp/ch12/ligand.php) Also, other similar images ...
ecneics's user avatar
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3 votes
1 answer
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Why does iron carbonyl have five carbonyl groups instead of six or four?

When finely divided iron combines with carbon monoxide, we get the complex $\ce{Fe(CO)_5}$. Why the number 5? It doesn't even relate to the orbital theory wherein we can see the number of empty and ...
Dusty_Wanderer's user avatar
1 vote
1 answer
147 views

How can we predict the formula of a coordination compound by just knowing the ligand and central metal? [closed]

Question: On complete reaction of $\ce{FeCl3}$ with oxalic acid in aqueous solution containing $\ce{KOH}$, resulted in the formation of product A. The secondary valency of $\ce{Fe}$ in the product A ...
Tatai's user avatar
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1 vote
1 answer
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How does the anti-bonding eg orbital (eg*) affect the bonding of ligands?

In the molecular orbital for octahedral metal-ligand complexes, there is an eg orbital and an eg* orbital. When the d orbitals on the metal split, it will fill up some of the eg* orbitals I believe. ...
M.L's user avatar
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1 vote
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515 views

Strength of Pi Donor and Acceptors as Ligands

The spectrochemical series is usually known as the "strength" of the ligands. It makes sense on a basic level as the more willing a ligand is to donating its electrons (via a $\sigma$-bond), ...
chematwork's user avatar
1 vote
0 answers
191 views

Tetrahedral complex and vibronic coupling or different rule for d-d transition?

I'm currently preparing a few slides for an upcoming talk in our group. I would like to mention some of the very basics regarding crystal field and ligand field theory as well, though this will not be ...
Justanotherchemist's user avatar
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0 answers
219 views

Is Porphyrin Planar?

I have been looking at this diagram from quite some time, I know the 18 pi electron cycle that forms porphin(e) is definitely planar but what about the whole molecule?... The Nitrogen's act as a ...
Informal Limits Lad's user avatar
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1 answer
350 views

Which of the following octahedral complexes absorbs the photon with the longest wavelength, λ?

I wonder which of the following absorbs photons with the longest wavelength, $\ce{[Cr(CN)6]^3-}$, $\ce{[Cr(SCN)6]^3-}$ and $\ce{[Cr(H2O)6]^3+}$. I know the one to absorb the highest wavelength should ...
pinkUnicorn999's user avatar
5 votes
0 answers
310 views

Molecular orbital diagram for carbene-metal and carbodiphosphorane-metal interaction

I am interested in understanding how carbenes and carbodiphosphoranes interact differently with a transition metals. I would like to use qualitative molecular orbital theory arguments (with an ...
Yoda's user avatar
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2 votes
0 answers
71 views

Maximum absorption wavelength directly proportional to the donor number of the ligand for a copper(II) coordination complex

I am looking at a set of results showing a directly proportional relationship for an increasing maximum absorption wavelength (UV-Vis spectra) with increasing donor number of solvent ligands. The ...
user avatar
3 votes
1 answer
11k views

Is there an 'easy' way to determine if a ligand is a pi acceptor, donor or neutral?

First of all I am confused how something can be pi neutral? something either does or doesn't have filled p orbitals for example. given something I have never seen acting as a ligand before like ...
user avatar
3 votes
1 answer
727 views

Denticity of bridging ligands

How would we assign denticity to bridging ligands? For eg, consider $\ce{NH^-_2}$, it has 2 lone pairs and can hence act as a bridging ligand, making 2 metal-ligand bonds. So I thought it should be ...
K. Chopra's user avatar
5 votes
1 answer
397 views

Intuitive Explanation for why more negative charge on ligand does not imply more splitting effect?

I have studied coordination chemistry as part of my school curriculum and we covered Crystal Field Theory as our final theory, and the book says that Ligand Field Theory and Molecular Orbital Theory ...
FoundABetterName's user avatar
2 votes
1 answer
672 views

Why does this ligand form 6-coordinate complexes with Transition elements and 8-coordinate complexes with Inner transition elements? [closed]

The ligand given above shows different denticities with common transition and inner-transition metal ion i.e. 6 and 8. The extra two denticities come from the two Nitrogen having 1 lone pair each. I ...
R_Squared's user avatar
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7 votes
1 answer
2k views

What is the shape of [Cr(NO)₄]?

I was learning about crystal field theory recently. I am quite confused about predicting the shape of $\ce{[Cr(NO)4]}$ complex because I am not able to conclude whether it will be square planar or ...
Chem-Learner's user avatar
3 votes
1 answer
5k views

Why is the crystal field splitting energy larger for square planar than octahedral complexes?

I recently came across a fact that for the same combination of metal and ligand, the crystal field splitting energy for square planar complexes is larger than that of the corresponding octahedral ...
Chem-Learner's user avatar
0 votes
2 answers
540 views

Why are chelating ligands often used to treat poisoning by heavy metals (e.g. mercury, lead)?

Why are chelating ligands such as EDTA often used to treat poisoning by heavy metals (e.g., mercury, lead)? I have a vibe that it has something to do with the lone pairs of electrons that are able to ...
sophia's user avatar
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2 votes
1 answer
337 views

Effective Bohr Radius in Transition Metal Complexes?

I am playing around with a toy model of a transition metal complex where the HOMO are $d$-electron states of predominantly transition metal character. Let's say this is a $d^1$ (or $d^9$) system and ...
user157879's user avatar
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0 answers
3k views

Finding the wavelength of maximum absorption and Crystal Field Splitting of [Ni(H2O)6]2+

(I haven't been here for a long time, so tell me if my formatting is fine) Given The $\ce{[Ni(H2O)6]^2+}$ complex appears green in solution from the transmitted light. Estimate the wavelength of ...
Choop's user avatar
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1 vote
1 answer
3k views

About Fe(III) and Fe(II) coordination complexes

Why does Fe(III) form octahedral coordination complexes if it has 5 electrons in its d-orbitals? I understand that Fe(II) has 6 electrons in its d-orbitals and 6 lone pairs from 6 ligands as the 12 ...
chematwork's user avatar
0 votes
1 answer
215 views

What is the binding mode of the ligand in complexes with quadruple metal-metal bonds?

I'm wondering which atomic orbital is left in a complex with quadruple metal-metal bond to bind the steric ligand, since all d orbitals except the x2-y2 are used for the metal-metal bonds? or is it ...
John's user avatar
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3 votes
0 answers
5k views

Why CO is a stronger and more common ligand than N2?

Both N2 and CO are considered sigma-donor and pi-acceptor. Their MO diagram is similar, so I wonder why CO binds generally more strongly and it is a more common ligand.
C.X.F.'s user avatar
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1 vote
0 answers
125 views

Why does the hexachlorocopper(II) ion not form?

I am not entirely sure if this question has been answered before, but I was wondering why when copper forms a complex ion with chlorine there are only 4 chlorine ligands. I asked my teacher and he ...
sab hoque's user avatar
  • 247
11 votes
2 answers
12k 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?
user226375's user avatar
1 vote
0 answers
580 views

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 ...
Nha's user avatar
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1 vote
0 answers
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Difference in properties of water as ligand vs 'in lattice'

I'm trying to understand the difference in properties between water in crystals in different positions in the lattice. In this wikipedia article It quotes: Both notations can be combined as for ...
tomhepz's user avatar
  • 111
3 votes
1 answer
1k 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{...
S R Maiti's user avatar
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0 votes
2 answers
8k views

What is the number of unpaired electrons in (Fe(H2O)5NO)2+? [closed]

Given the fact that $\ce{NO+}$ is a strong field ligand and iron is in the +1 oxidation state, the valence orbitals of $\ce{Fe+}$ must undergo rearrangement from $\mathrm{3d^{6}4s^{1}}$ to $\mathrm{3d^...
user3244786's user avatar