# Questions tagged [coordination-compounds]

This tag is for questions concerning coordination compounds including but not limited to ligand properties, metal properties, orbital splitting, micro- and macroscopic properties of entire complexes etc. For complexes where carbon monoxide is the only ligand, use the [carbonyl-complexes] tag instead. For organic catalysts or proteins, the tag is applicable if the question is about the metal’s direct coordination sphere.

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### Do “weak-field” and “high spin” complexes refer to the same thing?

I will keep it brief; I know that there are weak field, "moderate" field, and strong field ligands and that these might contribute to a complex being high or low spin overall. My question is,...
1answer
34 views

### Iron-II to iron-III change in complex formation

We have an iron dust sample, which is treated with hydrogen chloride in aqueous solution. The solution enters in a reaction with a sodium hydroxide powder, from which we obtain a precipitate. Could we ...
1answer
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### Does iron(VI) fluoride exist?

Why does $\ce{FeF6}$ not exist? There are hexavalent iron compounds, so that is not the problem. There is the $\ce{[Fe(CN)6]^3-}$ ion, so there doesn't seem to be a steric problem.
0answers
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### How many stereoisomers are present in octahedral complexes of type MA3B2C?

Does $\ce{MA3B2C}$ type have optical isomerism or just geometric isomerism? I was told that it has three isomers, two cis and one trans. Are the two cis isomers optically active?
1answer
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### Toxicity of Mercury (II) Iodide and dicopper (I) tetraiodomercurate (II)

This is a continuation from my previous post. Could you please give me some info on the toxicity of compounds $\ce{HgI2}$ and $\ce{Cu2[HgI4]}$? I found on sigmaaldrich.com that these are very ...
0answers
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### Chemical properties of dicopper (I) tetraiodomercurate (II)

This is a continuation from my previous post. Where can I find information on the chemical properties of $\ce{Cu2[HgI4]}$? I found a mention that in reaction with $\ce{Na2S2O3}$ in presence of acid ...
0answers
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### How to use Sodium Thiosulfate for fixing dicopper (I) tetraiodomercurate (II)?

DISCLAIMER DO NOT TRY TO DEMERCURATE USING DESCRIBED PROCEDURE. CONSULT YOUR EMERGENCY SERVICE. I found a discrepancy between a government-approved procedure of living quarters demercuration and the ...
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### Effective Atomic Number stability comparison for equidistant values

EAN(Effective Atomic Number):- The amount of electrons around the central ion. EAN=(Atomic number - oxidation state)+(Number of electrons donated by ligands) Sidgwick's EAN Rule:- Sidgwick suggested ...
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### Equilibrium of zinc ion with ammonia

In my chemistry lab, we are testing the amphoteric properties of this metal. I understand zink can react with an acid or a base to form different compounds in solution based on pH. In one part of the ...
0answers
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### In the aquation of cis-platin, why are the chloride ligands, and not ammonia, replaced with water, despite chloride's larger trans effect?

https://doi.org/10.1021/ic000847w In this paper, the aquation of cisplatin is examined. When used to treat cancer, the chlorides are substituted with water molecules, which seems to go against the ...
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### Comparison of C=O bond strength in metal carbonyls

Find the weakest $\ce{C=O}$ bond among $\ce{[Mn(CO)6]+},$ $\ce{Fe[(CO)5]},$ $\ce{[Cr(CO)6]}$ and $\ce{[V(CO)6]-}.$ I thought the $\ce{C=O}$ bond strength would be lowest in $\ce{[V(CO)6]-}$ since the ...
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### Entropy and Gibbs Free Energy of Chelate Complexes

Of [Cd(NH2CH3)4]2+ and [Cd(en)2]2+ the stability of the latter is higher than the former attributing to chelation in the en complex .This is evident from the fact that the Gibbs Free Energy change for ...
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### Comparing bond lengths in metal carbonyls

Question: It's solution is given as: Now I don't understand which d$\pi$ electrons have been considered here. For example, in $\ce{Fe(CO)_5}$, according to this, number of d$\pi$ electrons would be ...
2answers
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### Is glycinate ligand a monoanion or a zwitterion?

Glycinate as far as I can guess from the structure is a monoanion with negative charge on oxygen atom (though that negative charge is resonating). But when I used this logic in my exam it costed me 4 ...
1answer
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### Octahedral, Tetrahedral or Square planar? [closed]

In cases where a metal ion like, Fe(III), Cr(III), Pt(II) is made to react with a ligand species like oxalate, CN-, CO etc and it forms a complex then, How do we determine whether 6 ligands will be ...
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1answer
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### EDTA titrations of singly charged cations

It is well known that EDTA can be used for titrations involving complexations of highly charged metal cations, with the most well known being those of the alkali earth metals and transition metals. ...
0answers
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### Is the Co-ordination number of Cobalt always 6 in every co-ordination compound?

For example in the following compounds CoCl3.6H2O CoCl3.6NH3 CoCl3.5NH3 CoCl3.4NH3 in all of these complexes, we took the a)oxidation state of Cobalt as +3 ( since there are 3 Cl- ions and NH3 and ...
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### 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), ...
1answer
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### Why are complexes of type MA3B3 not optical active?

Complexes of type $\ce{MA3B3}$ have two geometrical isomers, namely: fac-isomer mer-isomer If we look closely at the mer-isomer, it has a plane of symmetry, so it is optically inactive. But the fac-...
1answer
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### Calculate EAN for [Fe(diars)2Cl2]Cl? [closed]

I know EFFECTIVE ATOMIC NUMBER (EAN) as the following • The sum of the number of electrons, donated by all ligands and those present on the central metal ion or atom in the complex is called an ...
2answers
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### How tetraamminecopper(II) is formed? [duplicate]

I'm trying to get a sense of how $\ce{Cu^2+}$ and $\ce{NH3}$ are bonded together because it doesn't make any! I understand that $\ce{NH3}$ has a lone pair of electrons that can be donated (right?), ...
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### Which acetate salt is blue and turns yellow when dissolved in water?

***Update Some questions I am considering to try to answer this question; When dissolving the powder in acetic acid, which ions are present? From what I've read, I haven't found any acetate salts ...
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### Crystal field theory: splitting energy and stability

In crystal field theory, we admit that in a coordination compound there are only electrostatic interactions between the d orbitals of the central metal cation and the ligands (which are considered as ...
2answers
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### The colors that we see [closed]

I have a question. When I was studying Coordination Compounds, I came across this para: When a sample absorbs light, what we see is the sum of remaining colors that strikes our eyes. Observed and ...
1answer
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### Bridging Hydride Covalent Model Electron Count - Hartwig

How can a bridging hydride be considered a 3 electron donor in the covalent model for electron counting? On page 3 of John Hartwig's "Organotransition metal chemistry" textbook [1], he lists ...
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### Describe the formation of the [PbCl4]2- complex ion

The $\ce{[PbCl4]^{2-}}$ complex ion is formed when $\ce{PbCl2}$ is exposed to excess $Cl^-$ ions in solution as explained here and here through the following reversible reaction: \ce{PbCl2(s) + 2Cl^-...
2answers
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### Explanation of the orbital energies resulting from Jahn-Teller distortion of octahedral complex using MO theory

I am confused about the energies of the orbitals after Jahn-Teller distortion of an octahedral complex. Take elongation for example. To my understanding, since the ligands on the $z$ axis move away, ...