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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20 views

Why does fe +2 have a hexaaqua and not penta, octaaqua?

Why does fe +2 have a hexaaqua and not penta, octaaqua? Similarly, why does copper have Hexaaqua as well since in the case of copper, the reason that it follows so to have 36 electrons to make itself ...
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Sp2d hybridisation [closed]

What's the deal with Cu(en)2++ since it's C.N. 4 and Cu stays as 3d9 in +2 state how is it sp2d and not sp3 infact, why does sp2d even exist, if a p orbital is already vacant for the ligand to use
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Doubt regarding VBT and nature of NH3 as a ligand

Why is [Ni(NH3)6]++ outer orbital but [Co(NH3)6]+++ is not? Also some help on the order of the spectrochemical series would be really appreciated
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What is the mechanism of amination of aryl halide using cuprous oxide catalyst? [closed]

The simplified version of the reaction is $$\ce{Ph-Cl + 2 NH3 + Cu2O ->[\pu{200 °C}, \pu{150 atm}] Ph-NH2 + CuCl2 + H2O}.$$ I want to know its mechanism and the role of copper catalysis, and also ...
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Can someone help with the nomenclature of this metal complex. MarvinSketch is giving me trouble

I’m trying to get a name for the structure above using MarvinSketch for my undergraduate senior thesis. This is the first time I’ve had to draw a metal complex in MarvinSketch, and I’m having trouble ...
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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 ...
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Beer Lambert law when complex is tetragonal (Jahn-Teller elongated)

I wondered what modifications there would be to the Beer Lambert law to find the molar extinction coefficients for the solution if the solvent contained the ligands which bind to the metal centre of a ...
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Coordination compound nomenclature for [Cu(acac)(bpy)]BPh4

The title says it all really. I thought it would be acetylacetonatobipyridinecopper(II) tetraphenylborate. Is this correct? I feel as though it looks a bit clumsy and wasn’t sure if I was supposed to ...
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Comparison between Molecular Orbital Theory and Valence Bond Theory

I have been reading about introductory Molecular Orbital Theory lately. Till now, I have used Valence Bond Theory to evaluate bonding. I have a few questions about it:- In VBT, we used the idea that ...
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Why does [Ni(gly)2] show optical isomerism despite having no chiral carbon?

For optical isomerism chiral carbon should be present i.e. carbon with four different groups but this compound doesn't have one then why does it show optical isomerism?
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1answer
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Ambiguity in definition of primary valency in Werner's theory

In Concise Inorganic Chemistry (5th Edition) on page 196 , the primary valency of $\ce{[Co(NH3)5Cl]Cl2}$ is given to be 2. In other textbooks and in the question here, we get the idea that: The ...
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1answer
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Wavelength and Colour in Coordination complexes

My textbook said that coordination complexes with weak field ligands require a larger wavelength for obtaining enough energy for electron transfer(and hence, the manifestation of a colour), but if E = ...
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1answer
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Naming and structure of PtCl4.2HCl (complex/coordination compound)

Given that $\ce{PtCl4.2HCl}$ when reacted with excess of $\ce{AgNO3}$ produced zero moles of $\ce{AgCl}$, I understand that all the chlorine atoms are inside the coordination sphere. But what will the ...
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2answers
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Is plane of symmetry a necessary and sufficient condition for optical inactivity in coordination compounds? [closed]

In organic chemistry, we have to check for all three types of symmetry in a compound to check its chirality, ie, plane, alternate axis and centre of symmetry. But in coordination compounds, do we need ...
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Visualizing the e_g and t_2g orbitals in case of tetrahedral crystal field splitting

I am reading about the crystal field theory (CFT) for the case of tetrahedral coordination entities. I understand that the $\mathrm{t_{2g}}$ orbital is nearer to the ligand than the $\mathrm{e_g}$ ...
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Ionic radius for tetrahedral metal–ligand complexes

The ionic radii for metal–ligand complexes that are in an octahedral coordination are easy to find. I understand that when the $\mathrm{e_g}$ orbital is filled, the ionic radius increases because the ...
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Nickel(II) acetylacetonate crystals coming out blue

An experiment in my class has us synthesising the acetylacetonate complex from hydrated nickel chloride being added to a solution of ammonia, acetylacetone and water. The products came out pale blue, ...
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1answer
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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 ...
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1answer
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Has a low spin tetrahedral Ni(II) complex been synthesised?

How can $\ce{Ni(II)}$ form a low spin tetrahedral compound? I was not able to find such compounds. $\ce{Ni(II)}$ will have $\mathrm {4s^03d^8}$ and tetrahedral needs $\mathrm{sp^3}$. So $2$ electrons ...
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1answer
44 views

Jahn Teller Effect on Metal Complexes

I've been learning how the Jahn Teller Distortion effects the orbitals in Metal complexes and how the splitting of eg and t2g orbitals happens. But the book mentions that the effect is strong for ...
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Molar conductivity in compounds showing coordination isomerism

Question Which of the following complex has lowest molar conductivity? $\ce{[Co(NH3)6][Cr(NO2)6]}$ $\ce{[Cr(NH3)5(NO2)][Co(NH3)(NO2)5]}$ $\ce{[Cr(NH3)4(NO2)2][Co(NH3)2(NO2)4]}$ $\ce{[Co(NH3)5(NO2)][...
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2answers
858 views

Possible structure if a compound like AB4 is polar?

I was asked the following question in JEE Mains (2nd September, Shift 1) 2020, If a compound AB4 is polar (having non-zero dipole moment), then it's structure could be (A) Square planar (B) ...
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Metal coordination in enzymes: What type and number of bonds form between amino acid residues and Fe(II)?

My understanding: Transition (d-block) metals, as found in intracellular proteins, are limited to about 10 elements including amongst others Fe, Ni, and Cu. Due to the reductive environments inside ...
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Coordination number in π-complexes

I wanted to know what is the coordination number of the metal atom in π-complexes like Zeise's salt, ferrocene and dibenzene chromium. I found some data on it but its a bit contradicting. Can anyone ...
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Nomenclature of K2(PdCl4) [closed]

In the compound $\ce{K2[PdCl4]}$, the oxidation state of Pd is +2 so as per the nomenclature rules, the name of the central metal inside the coordination is simple if it's a cation. So if we name the ...
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57 views

Adding a base and a salt to a hydrated complex

The question goes like this: $\ce{Fe(NO3)3}$ V= $\pu{1 liter}$ and $\ce{[Fe(NO3)3]} =\pu{0.1 moles/liter}$. Calculate the $\mathrm{pH}$ of this solution using the values of $K$ given. We add a solid ...
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1answer
57 views

Molar conductivity of coordination compound [duplicate]

The compound is $\ce{[Cr(H2O)6]Cl3}$. Which isomer has least molar conductivity ? Correct answer : $\ce{[Cr(H2O)4Cl2]Cl.2H2O}$ My answer : $\ce{[Cr(H2O)3Cl3].3H2O}$ Molar conductivity is directly ...
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Parallel between polarisability of donor atom and CFS strength

Observing the strength of crystal field splitting by different ligands, can the following be considered?: Most of the members in the series are ligands where the donor atom is nitrogen, oxygen or ...
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1answer
129 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 ...
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1answer
64 views

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

What change takes place in the denticity of this ligand if it is an inner-transition metal ion vs a common transition metal? Primarily, why does the ligand behaves differently with the two situations ...
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1answer
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Formal charge in a co-ordinate covalent bond

In coordinate bond, Does the donor atom have positive formal charge and the acceptor atom have negative formal charge? For example, in carbon monoxide the oxygen atom donates its lone pair of ...
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Infra red stretching frequency of carbon monoxide ligand in borane carbonyl compared to that of free carbon monoxide

Why is the infrared stretching frequency of $\ce{CO}$ in the borane carbonyl $\ce{BH3CO}$ more than that of free $\ce{CO}$? Is there any real explanation for this? There will be a small amount of ...
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Protonated forms of EDTA and their constants of formation with metal ions

It is widely known that the fully deprotonated form of EDTA (usually written as Y4-) is the only form that is significantly involved in complexation reactions. From what I have read, this accounts for ...
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1answer
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What is the magnetic moment of tris(oxalato)nickelate(IV)?

I'm really struggling with finding the magnetic moment of this complex: In the solutions, it says that it is 2.83 BM (which corresponds to 2 unpaired electrons). However, in drawing out the d orbital ...
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1answer
84 views

How to predict which complex is formed and which are soluble?

How does one come to know (in this table) which metal cations form ammonia complexes and which ones form hydroxy complexes on reaction with $\ce{NH4OH}$ Reference: J.D Lee - Concise Inorganic ...
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1answer
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Determination of spinel structure by CFSE

$\ce{CuFe2O4}$ has inverse spinel structure, but $\ce{ZnFe2O4}$ has normal spinel structure. Explain. I know that normal spinels have a structure like $\ce{(A^{II})^{tet}(B^{III})^{oct}_2O_4}$-like ...
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1answer
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I am having problem with this question including topics of redox reactions and charges [duplicate]

What is the oxidation number of $\ce{Fe}$ in $\ce{K4[Fe(CN)6]}$? This seems to be a pretty easy problem. Just input the oxidation numbers of everything and equate for 'x'. But the problem is that I ...
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CFSE Calculation

I have $\ce{[ML6]}$ & $\ce{[MD6]}$ as two complexes. I know the $\Delta_0$ & hybridisation of each of them. How do I calculate the CFSE for $\ce{[ML4D2]}$ ? This is my way of thinking : I can ...
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55 views

In which condition CO uses the oxygen end for bonding?

Generally Metal Carbonyl complex are formed from Carbon end. Is it possible under some specific condition that the Oxygen end is used? (PS -I know about the structures of M-CO bonding)
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Aquo metal complex structure

Draw the structure of the complex $\ce{Co(NO_3)_2*6H_2O}$ i) without and ii) with one of the nitrates being in the coordination sphere as a bidentate ligand and identify if the inversion center is ...
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Comparing $\ce{PPh3}$ and dppe

The ligands $\ce{PPh3}$ and dppe (dppe = 1,2-Bis(diphenylphosphino)ethane) are both strong field ligands, but is one obviously a stronger field ligand than the other or are they roughly equal? The ...
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1answer
223 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 ...
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1answer
292 views

What do 'sigma' and 'pi' in front of ligands in the formula of a coordination compound mean?

The following coordination compound was given in the book Concise Inorganic Chemistry by J.D. Lee (Adapted by Sudarsan Guha) under the topic 'Effective Atomic Number (EAN)': $\ce{[Ti(\sigma -C5H5)2 (\...
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Distinguishing between different geometries of bromochlorobis(triphenylphosphine)platinum(II) using ¹⁹⁵Pt NMR

Question The question off which I am basing my question assumes that $\ce{[PtClBr(PPh3)2]}$ can exist in either the square-planar or tetrahedral geometry. If one would use $\ce{^{195}Pt}$ NMR ...
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1answer
289 views

Why is acetate a monodentate ligand?

Why is the acetate ion considered a monodentate ligand as opposed to a bidentate ligand considering both oxygen atoms can donate their respective lone pair of electrons?
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1answer
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Structural isomers of hexaammineiron(III) hexacyanidocobaltate(III)

Find the number of structural isomers of $\ce{[Fe(NH_3)_6][Co(CN)_6]}$ This was a question solved by my teacher as follows: The $\ce{CN}$ will show linkage isomerism while $\ce{NH_3}$ and $\ce{CN}$ ...
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1answer
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Naming of [Pt(py)4][PtCl4]

Why is $\ce{[Pt(py)4][PtCl4]}$ called tetrakis(pyridine)platinum(II) tetrachloridoplatinate(II) and not tetrapyridineplatinum(II) tetrachloridoplatinate(II)? I thought you use tetrakis for ligands ...
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2answers
297 views

Why can't ligands with “locked structures” undergo chelation?

The following quote is from the book Concise Inorganic Chemistry by J.D. Lee (Adapted by Sudarsan Guha), from the chapter "Coordination Compounds", page 177: ...it must be noted that $\ce{NH2NH2}$ ...
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1answer
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What is the electron count in this nickel complex?

Our class has started learning about electron counting using the ionic method. I was having a little difficulty, especially when there are two metals in one complex, so I looked at Wikipedia for help. ...

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