Questions tagged [ligand-field-theory]
The ligand-field-theory tag has no usage guidance.
43
questions
6
votes
1
answer
348
views
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 ...
0
votes
0
answers
33
views
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 ...
3
votes
1
answer
61
views
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 $...
0
votes
0
answers
36
views
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 ...
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 $\ce{PF3}$ ...
0
votes
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 ...
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 ...
0
votes
0
answers
48
views
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 ...
-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 ...
0
votes
0
answers
131
views
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 ...
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 ...
-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, ...
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 ...
-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 ...
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.
...
2
votes
0
answers
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 ...
3
votes
1
answer
383
views
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 ...
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 ...
1
vote
1
answer
697
views
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. ...
1
vote
0
answers
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), ...
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 ...
1
vote
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 ...
0
votes
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 ...
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 ...
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 ...
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 ...
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 ...
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 ...
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 ...
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 ...
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 ...
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 ...
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 ...
0
votes
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 ...
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 ...
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 ...
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.
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 ...
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?
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 ...
1
vote
0
answers
96
views
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 ...
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{...
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^...