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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1answer
27 views

Coordination complex - nitrito-N & nitrito-O

I am currently learning the coordination compounds and encountered a new isomerism called linkage isomerism. I am thinking that if I want to get some $\ce{[Co(NO2)6]^3-}$, I should have to dissolve $\...
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0answers
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My EDTA titration isn't giving the right titre

I am, as a fun off-syllabus investigation, looking at hard water and how effective the EDTA titration method is, for permanent and temporary hard water. I ran a titration today and had horrific ...
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Determining the direction of electron transfer in a coordinate bond [closed]

I am curious as to how electron transfer takes place in a co-ordinate bond in complexes. Take for example, the nitrito-$\ce{O}$ molecule, where $\ce{M}$ is a metal, $$\ce{M<—O—N=O}$$ In the ...
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1answer
23 views

Determining difference between co-ordination complexes of copper [duplicate]

What's the difference between the co-ordination compounds $\ce{Co.(H2O)6}$ and$\ce{[Co(H2O)6]^2+}$?
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1answer
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Stability of complexes based on number of rings [duplicate]

$\ce{[Co(edta)]^-}$ has 5 rings in total and in $\ce{[Co(en)_3]^{3+}}$, there are 3 rings. The stability of the former is more than that of the latter. The reason I was told was that a complex with ...
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can anyone provide me the list of exceptions in hybridization associated with coordination complexes? [closed]

I want a list (or atleast what u can list) of exceptions or deviations from natural hybridization that a particular complex shows. I am always keen to know more about things that don't follow the ...
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1answer
32 views

Aren't isothiocyanate and thiocyanate ligands monodentate?

I will keep it brief; if I generalize what an assignment is telling me, then a metal complex with 2 (iso)thiocyanate ligands would be named "bis(isothiocyanate)...metal(oxidation state) or bis(...
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2answers
224 views

Explain on the basis of valence bond theory that tetracyanonickelate(II) ion with square planar structure is diamagnetic

Answers on the internet suggest that tetracyanonickelate ($\ce{([Ni(CN)4]^{2-}}$) with square planar structure is diamagnetic because $\ce{CN-}$ is a strong field ligand and causes pairing, but my ...
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Hybridization of tetraamminecopper(II) [duplicate]

So I wanted to find out all details including hybridization, number of unpaired electrons and dipole moment, etc. for the compound $\ce{[Cu(NH3)_4]^2+}$ Does anyone know why? Here is what I found on ...
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1answer
179 views

Finding the valency of transition metals in coordination complexes

I understand how to find the valency of atoms in small organic compounds. For instance, for CH4, the valency of carbon is 4, while the valency of each hydrogen is 1. But for a coordination complex, ...
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Do Metal Carbonyl complexes exhibit multiple back donation at the same time?

I came across a question which renewed one of my doubts that I had regarding bonding in metal Carbonyl complexes. According to me, metal should exhibit multiple back donation at the same time. ...
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Why can zinc porphyrins assume 5 coordinate geometries?

It has been reported that 5-coordinate geometries are possible and stable for Zn(II) porphyrin complexes. How do these complexes form and why are they stable when other 5-coordinate geometries of Zn(...
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Calculating electric reduction(or oxidation) potential for complex ion formation equation?

I would like to calculate the standard electric potential($E°$) for the following equation. $$\ce{Pt^{2+}(aq) + 4Cl-(aq) → [PtCl4]^{2-}(aq)}$$ $K_f = \pu{1.0 * 10^16}, T =\pu{ 298K}$ I figured out $ΔG°...
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1answer
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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,...
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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 ...
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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.
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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?
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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 ...
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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 ...
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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 ...
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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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78 views

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 ...
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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 ...
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1answer
46 views

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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2answers
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Why transition metal chloride complex have lower reduction potential than metal aqua ions?

Why transition metal chloride complex have lower reduction potential than metal aqua ions? For example: $$ \begin{align} \ce{Au^3+(aq) + 3 e- &-> Au(s)} &\quad E^\circ &= \pu{+1.52 V}\...
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1answer
328 views

IUPAC name of H[AuCl4]

Is $\ce{H[AuCl4]}$ tetrachloroauric [III] acid or hydrogen tetrachloroaurate[III]? As per the rules I have studied the latter name is correct. Then why am I getting the former name mentioned ...
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Why does beryllium have an exceptionally high hydration energy?

You would expect solubility of Group $2$ fluorides to increase down the group, as lattice energy plummets much more sharply than hydration energy does. For the most part, this is true: $\ce{BaF2}$ is ...
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1answer
47 views

Why is hydrated beryllium ion acidic?

The beryllium ion, $\ce{Be^{2+}}$, forms the aquo complex $\ce{[Be(H2O)4]^{2+}}$. According to LibreTexts, this complex is acidic in solution: $$\ce{[Be(H2O)4]^{2+} + H2O -> [Be(H2O)3OH]+ + H3O+}$$ ...
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Are high spin complexes and spin free complexes the same thing?

While solving some Coordination Compounds problems, I came across a problem that asked Select which complex is high spin or spin free octahedral complex. The term 'spin free' sounds like a complex ...
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Why is tetrachlorocuprate (II) yellow if it is high-spin?

From my knowledge of transition metal complexes, tetrahedral complexes generally have less splitting (compared to octahedral complexes) because they only involve four ligands are they aren't placed ...
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1answer
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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. ...
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2answers
54 views

Why iron(II) spectrometry is not measured in distilled water and it requires a complexing agent like o-Phen?

We know that iron(II) ions in water have a green colour. Why we cannot draw the spectrum of iron(II) directly in distilled water to measure the absorbance then determine the concentration of iron(II)? ...
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0answers
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Why does π-backbonding in a metal-carbonyl complex lead to a decrease in C-O bond strength?

I understand that π-backbonding in this complex involves the σ-donation of carbonyl to an empty d orbital of the metal, and the π-donation of the d electrons of the metal to the π* MO of the carbonyl. ...
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2answers
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What exactly is hydrolysis? What are the products of hydrolysis of aluminium?

I came across three reactions while studying p-block compounds in inorganic chemistry. $$\ce{2Al + 2NaOH + 6H2O -> 2 Na[Al(OH)4] + 3H2} \label{eq:1} \tag{1}$$ $$\ce{Al2O3 + 2NaOH + 3H2O -> 2 Na[...
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1answer
54 views

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. ...
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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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0answers
41 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), ...
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1answer
114 views

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-...
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1answer
62 views

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 ...
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2answers
58 views

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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67 views

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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32 views

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 ...
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2answers
86 views

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 ...
5
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1answer
150 views

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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0answers
105 views

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^-...
6
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2answers
133 views

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, ...

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