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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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Crystal Structure of FeSO4.7H2O [closed]

Question: No. of H-bonds in $\ce{[Fe(H2O)6]SO4.H2O}$? My Doubt: I am confused in the correct crystal structure of $\ce{[Fe(H2O)6]SO4.H2O}$. Is the structure for $\ce{[Fe(H2O)6]SO4.H2O}$ attached below ...
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Is double excitation of nitrogen possible, and would it be able to use it as a central atom in a coordination complex?

I’m 17 and in my 2nd year of high-school (we have it a tad different here in the Czech Republic) and am interested in theoretical chemistry so that’s the explanation of the nature of my question. So, ...
Prokop Hoza's user avatar
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Paramagnetism in coordination complexes

A complex is classified as paramagnetic or diamagnetic based on the electronic configuration of the central atom/ion. Should the properties (para/dia) of surrounding ligands also affect the nature of ...
Sarah's user avatar
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How does Hexaaquanickel(II) show color

I have studied that there must be unpaired electrons in $t_2g$ orbitals so that they can make transition to the eg orbital by absorbing energy from light. But in $\ce{[Ni(H2O)6]^2+}$ $\ce{Ni^2+}$ has $...
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Splitting of the d$_{xy}$ orbital in square planar transition metal complexes

In square planar complexes, the d$_{x^2-y^2}$ occupies the highest energy level due to it interacting greatest with the ligands. The d$_{z^2}$ orbital is also raised slightly higher in energy than the ...
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Difference in the absorption spectrum of gaseous atoms and complex ions

An absorbance spectrum is a graph that shows how much light is absorbed by the material at each wavelength of light. Both spectra are due to electronic transition, but for gaseous atoms, this spectrum ...
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Magnetic moment and pairing of electrons in hexaaquairon(III)

I understand that $\ce{H2O}$ acts as a strong ligand for $\ce{Fe^3+},$ $\ce{Cr^3+},$ and $\ce{Co^3+}.$ So, shouldn’t the electrons pair up in the $\mathrm{t_{2g}}$ orbitals? Wouldn’t that cause a ...
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Why each atom is given zero oxidation state for the coordinate bond? [closed]

How a coordinate bond can be formed by donor atom more electronegative than acceptor atom ? How electrons can go from the donor atom overcoming the nuclear force in this case? And even if the ...
Rohit P L's user avatar
-3 votes
1 answer
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Does cobalt form square planar complexes? [closed]

So I came across a question where we were required to identify the possible central metal atom using the following clues. An aqueous solution of metal ion M1 reacts separately with reagents Q and R ...
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Why can't group 2B metals (Zn, Cd, Hg) form complexes with ligands such as CO, nitrosyl (NO), and olefins but do from complexes with NH3, CN- etc?

Why Group 2B metals (Zn, Cd, Hg) can form complexes with Ammonia ($\ce{NH3}$), Cyanide ($\ce{CN-}$) etc. and not with ligands such as carbonyl ($\ce{CO}$), nitrosyl ($\ce{NO}$), and olefins? What I ...
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Why is Chromium hexacarbonyl diamagnetic?

So there was a question in coordination chemistry regarding the nature of $\ce{[Cr(CO)_6]}$ The book had the question under VBT and solved it using "strong ligands cause all electrons to pair up&...
Aurelius's user avatar
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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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Pairing of electrons in Nickel in presence of strong ligand(tetrahedral)

For tetrahedral CFSE, Nickel's last 6 electrons will go in the t2g set of orbitals. Since it is already the higher energy orbital, pairing should NOT happen right? However, all internet sources I ...
Mohammed Hamza's user avatar
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D-d splitting in transition metal ions

Cu+2 ion has total of 9 electrons in its 3d orbital. When it undergoes d-d splitting an electronic transition can take place between t2 and e as in {Cu(CN)4}-2 complex because of the presence of one ...
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Charge of a complex ion [closed]

Consider $\ce{[Cr(H2O)6]^3+}$, the charge on the Chromium before the water molecules react is $3+$, clearly each water ligand contributes one lone pair, meaning the formal charge should be $3-6=-3$ (...
nav op's user avatar
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Why do the carbonyl oxygens in EDTA not participate in coordination?

I recently had two, very brief lectures on coordination compounds. In those lectures, my teacher mentioned EDTA because of its importance in analytical chemistry and its very stable complexes and ...
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Transition of electrons between t2g and eg to give colour of coordination compounds

In the case of a hexaaquairon (III) complex, the iron (III) ion has 5 electrons, each singly occupying one d orbital. As the d orbitals are occupied, the vacant 4s, 4p and 4d orbitals are hybridised ...
Tabi Khan's user avatar
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Question on electron density

I was working with ammonia ($\ce{NH3}$) and phosphine($\ce{PH3}$). Both have lone pair electron. But $\ce{NH3}$ is stronger base (Lewis base) than $\ce{PH3}$. I was told by my instructor that it is ...
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Electron configuration in benzene chromium tricarbonyl

I am not sure what is the electron configuration in benzene chromium tricarbonyl? From what I can work out, Cr is in 0 oxidation state (since all ligands are neutral). The complex is tetrahedral so ...
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Jahn-Teller Distortion: How to compare magnitudes (in Cu2+ complexes)?

Octahedral complex of copper(II) undergo structural distortion (Jahn-Teller). Which one of the given copper(II) complexes will who the maximum structural distortion? (en - ethylenediamine) (A) $[Cu(...
magneticMono_Poal247's user avatar
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1 answer
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Determining High Spin or Low Spin Configuration: Influence of Weak and Strong Field Ligands

Can a coordination complex be classified as high spin if it possesses the same number of unpaired electrons in both weak and strong field ligand environments? I am curious about the factors that ...
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On the geometry of quadra-coordinated coordination complexes [duplicate]

How do we tell whether a complex with a four coordinated central metal ion takes on a square planar geometry or a tetrahedral geometry?
XXXMATHEMATICION's user avatar
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Products formed on reaction of aqueous solution of iron(III) nitrate nonahydrate

Crystalline iron(III) nitrate nonahydrate, Fe(NO3)3.9H2O, has a very pale violet color. When added to water, the crystals dissolve to form a brown solution. Treatment of this brown solution with ...
Priyanshu Kumar's user avatar
1 vote
2 answers
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Why wont Al(OH)3 form in this reaction?

I am in grade 11. We were learning qualitative salt analysis and my teacher wrote a reaction on board - $$\ce{Al^3+ +H2O\rightarrow[Al(H2O)6]^3+}.$$ Now as far as structure of the complex is concerned ...
Aleph's user avatar
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Why does the answer given consider octahedral splitting even though there is no specification of the complex

My textbook (NCERT Chemistry Part 1) gives this question as an example: Why is $\ce{Cr^2+}$ reducing and $\ce{Mn^3+}$ oxidising when both have $d^4$ configuration? And the solution given along with ...
Harshul's user avatar
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1 answer
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Why do most sulphate salts have water of crystallization in them?

Looking at most of the sulphate salts (there are so many but just to name some Epsom salt, blue vitirol, gypsum...) they have some amount of water crystallized within them (Epsom salt is $\ce{MgSO4....
some random person's user avatar
5 votes
1 answer
157 views

Is concept of weak and strong field ligands applicable in valence bond theory?

I study coordination chemistry at high school. I have read about valence bond theory (VBT) and crystal field theory (CFT) as well. My teacher taught me that VBT is based on the experimental values of ...
InfinityLies's user avatar
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1 answer
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Colour of coordination compounds due to d-d transition

Hexaaquanickel(II) is green but tetracyanidonickelate(II) is colourless. On internet I found two explanations. One used valence bond theory that claimed there is no excitation of electron in ...
Harjot Dhillon's user avatar
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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1 answer
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Bond length in square planar coordination complex of Platinum

(Q): Select the correct statements for $[Pt(NH_3)_2Cl_2]$ : (a): Geometrical Isomerism (b): Optical Isomerism (c): All bond length are equal. (d): Chelation effect is effect. (e): Hydrogen bonding is ...
Ahmad Raza Beg's user avatar
2 votes
3 answers
242 views

How to calculate the pH of a solution with addition of a complex

The scenario is this. I have $50$ mL of $0.1$ M $\ce{NH4^+}$ at a certain temperature which gives it a $K_a=5.2\times 10^{-8}$. To this solution, I add $0.02$ moles of $\ce{Cd(NO_3)_2}$. It is known ...
Pen and Paper's user avatar
2 votes
0 answers
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Isomers of Pentaaminechlorocobalt(III) chloride

What kind of isomers does $\ce{[Co(NH3)5Cl]Cl2}$ exhibit? I can rule out geometrical and optical due to there being $\ce{5 NH3}$ ligands which central metal atom cannot have different positions of $\...
Razz's user avatar
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Color of coordination compounds

My book(Page $259$ section $9.5.5$) says that the color mainly comes from absorption of light in the coordination compound: The color is complementary of the wavelength it absorbs , the wavelength ...
Razz's user avatar
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1 answer
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Reason behind paramagnetic substances having color

I've read in many books that paramagnetic substances are coloured while diamagnetic substances are colourless (yes there are some exceptions too). But nowhere i could find a reason for this phenomenon....
Gnanadeep Sai's user avatar
3 votes
0 answers
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What prevents an octahedral complex from always assuming the quadratic planar limiting case, due to the Jahn–Teller distortion?

When a given high-spin complex is Jahn–Teller distorted, this does not change the relative position of the total energy of the complex (assuming $\mathrm{d^{10}}$ configuration). Indeed, the ...
Rivinius's user avatar
2 votes
2 answers
444 views

What does the 2 in t2g stand for?

I have read so far that it is about whether the d-Orbital is symmetric to a C2 element perpendicular to its main rotational axis. If all the given orbitals in a group are symmetric to that element, ...
Rivinius's user avatar
1 vote
1 answer
496 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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0 answers
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What is the shape of tetraamminenickel(II) complex?

I have basic knowledge of crystal field theory (CFT) and how to predict geometries in complexes with a coordination number of 4. For $\ce{[Ni(NH3)4]^2+}$, we find that the metal center, $\ce{Ni^2+}$, ...
sushant_padha's user avatar
1 vote
1 answer
130 views

Significance of Character tables in d orbital splitting

When we have a molecule say (Co(NH2)6) hypothetically any octahedral molecule it has the point group of Oh and the character table shows the quadratic function such as ($z^2,2z^2-x^2-y^2$) ($xy, xz, ...
Harshdeep Chhabra's user avatar
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1 answer
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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
384 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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-2 votes
1 answer
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Do transition metals only carry d-electrons as valence electrons until group 11?

as I was revisiting my lecture notes in inorganic chemistry, I noticed that we treated the transition metals as elements where the energetic order of 4s ad 3d orbitals is reversed. For example ...
Mäßige's user avatar
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-4 votes
2 answers
105 views

Mechanism of S2Cl2 and NaHSO3 [closed]

I learned that NaHSO3 reacts with S2Cl2 to give Na2S4O6 as product. After looking up the structure of Na2S4O6, it confuses me that four sulfur atoms connect together. I couldn't figure out the exact ...
Shira's user avatar
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2 votes
0 answers
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Crown ether complex formation with cesium carbonate

I am searching for some papers which form complex between crown ether and caesium carbonate. But Most papers only use caesium carbonate as a base in the synthesis of crown ether, not ionic compound ...
Krang Lee's user avatar
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1 answer
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Do complexes of a metal distribute in between the water and an organic compound layer?

My original question is one that is stated in the title, and I also have some side questions too. I came across this question where you have a CuSO4 aqueous solution. Then you take an Ammonia aqueous ...
donthababakka's user avatar
3 votes
0 answers
58 views

Is aqua-meth-myoglobin (Fe3+) paramagnetic?

Is aqua-meth-myoglobin (Fe3+) paramagnetic? In this case, the iron has all 6 coordination positions occupied by ligands: 4 nitrogen atoms from the pyrrolic rings that compose the porphyrin, 1 ...
Arthur.chem's user avatar
-2 votes
1 answer
180 views

How does an equilibrium move when increasing the concentration of water?

I have the following equilibrium given: $$\ce{[Co(H2O)6]^2+(aq) + 4 Cl-(aq) <=> [CoCl4]^2-(aq) + 6 H2O(l)}$$ (I imagine the (l) for water is wrong, as the water is a part of the solution) The $\...
Rekeren1's user avatar
3 votes
0 answers
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Energy of d(x²-y²) and d(xy) orbitals the same with respect to trigonal symmetry?

In the orbital splitting diagrams of trigonal planar and trigonal bipyramidal complexes the d$_{x² - y²}$ and d$_{xy}$ orbitals have the same energy. I have always assumed that this is because they ...
Dion Silverman's user avatar
1 vote
0 answers
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Why is the distinction from "coordinative bond" useful at all? [closed]

There are 3 types of coordinative bonding, complex formation at the electron donor, complex formation at the electron donor acceptor and complex formation at the electron acceptor, so what is the ...
iwab's user avatar
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What is the actual complex formed in Fehling's solution?

What is the actual complex formed in Fehling's solution when Fehling’s solution A and Fehling’s solution B are mixed in equal amount? Wikipedia suggests: $\ce{[Cu(C4H4O6)2]^2-}$ But the book I follow ...
CHEMUMAN's user avatar

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