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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 [tag:carbonyl-complexes] 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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Confused in hybridisation [on hold]

I stumbled upon a compound [Ni(Nh3)6] ^2+ which has Nh3 as a strong field ligand. Which implies that pairing will occur and only one last d-orbital will be left with no electrons. But I couldn't ...
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Coordination number of complex resulting from sodium nitroprusside test

In my textbook the following reaction is given to identify sulphide ion : Na2[Fe(CN)5(NO)] + Na2S --> Na4[Fe(CN)5NOS] (violet solution) Here's what I want to know : Is NOS a newly formed ligand? If ...
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16 views

Coordination compounds ean rule [closed]

Which complex follow the sidgwick rule Ean rule where M =24?
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44 views

Why do tetrahedral organic molecules show stereo-isomerism, but not tetrahedral transition metal complexes?

Both types of molecules show different arrangements of the molecule in space, so they should qualify for optical isomerism right?
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1answer
40 views

Why do some ions form tetrahedral complexes more readily than others? [closed]

Why does Co$^{2+}$ readily form tetrahedral complexes such as [CoCl$_4$]$^{2-}$, whereas Fe$^{2+}$ usually forms octahedral complexes?
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0answers
38 views

Disproportionation of Au(II)

Cu(II) and Ag(II) complexes are known to exist while Au(II) is unstable and disproportionates to Au(I) and Au(III). My guess as a possible reasons to this effect is that Au(II) like Cu(II) and Ag(II) ...
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0answers
28 views

Do benzene rings participate in denticity [closed]

Do benzene rings will act has dentates in the following ligand? I've heard that benzene rings act as ligand but whether in this case too they will be electron donors??
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2answers
157 views

Statistical model of ligand substitution

Recently, I was told that in case of a particular step of a generic ligand substitution reaction: $$\ce{M(OH2)_{$N - n$}L_{n} + L <=> M(OH2)_{$N - n - 1$}L_{$n + 1$} + H2O}$$ The probability ...
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2answers
57 views

Is [Co(NH₃)₄Cl₂]Cl paramagnetic or diamagnetic?

$\ce{NH3}$ is known to be a strong field ligand, while $\ce{Cl}$ is known to be a weak field ligand. Is $\ce{[Co(NH3)4Cl2]Cl}$ a high spin complex or a low spin complex? I assumed this to be a high ...
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14 views

Changes in metal-ligand bond lengths of coordination compounds

Consider change in length of the metal-ligand bond in the following reaction: $\ce{[Cr(CN)6]^3- + e^- -> [Cr(CN)6]^4-}$ I initially had two theories (based on general electrostatics and d-...
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Why do polyoxometalates have good electrochemical/ redox properties?

Many authors are using polyoxomethalates immobilised in carbon nanomaterial as electrocatalysts for energy related reactions (ORR, HER, OER). Other metal alloys have also shown to be successful as ...
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Reason for synergistic effect in coordination compounds

I read that if we consider a coordination compound between a metal(say M) and a ligand (say CO,Carbon monoxide). The CO forms a coordinate covalent bond between its filled $\sigma$ orbital and the ...
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0answers
28 views

Metal complexes and bonding of ligands

I am currently learning about transition metal complexes, however I keep seeing complexes like $\ce{[Al(H2O)6}]^{3+}$ but aluminium isn't a transition metal. Is this a case that any metal can form a ...
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2answers
69 views

Colour change when excess ammonia added to [Cu(H2O)6]2+

Since ammonia is a stronger ligand than $\ce{H2O}$ shouldn't the colour of the new solution $\ce{[Cu(NH3)4(H2O)2]}$ be lighter as the energy gap will be higher and so light with higher frequency and ...
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1answer
31 views

Treatment of ambidentate ligands in geometrical and optical isomerism

Are ambidentate ligands considered different entities when they donate through different atoms? For example will a hypothetical square planar complex like [Pt(ONO)2(NO2)2] show geometrical isomerism?
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63 views

Is cobalt (III) hexaaqua paramagnetic or diamagnetic?

The complex ion $\ce{[Co(H2O)6]^3+}$ has $\ce{Co}$ in the $+3$ oxidation state, meaning it has an electron configuration of $[Ar] 4s^0 3d^6$. Therefore it has 4 unpaired electrons and would be ...
7
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1answer
52 views

How to determine the number of water ligands attached to Pd in palladium chloride aquacomplex PdClₓ · yH₂O?

Normally this can be achieved using UV-vis: there is a strong absorbance around wavelength 220 nm which varies based on the number of ligands. If the palladium concentration is too high, the solution ...
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0answers
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Can factors such as non-chelating ions in solution or the temperature of solution change the d orbital splitting of complexes?

My currently primitive understanding of metal complexes is that the d orbital splitting depends on: Identity of central ion Charge density of ligand Geometry of complex ion oxidation number of ...
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22 views

ML6 Type Coordinate Complexes - Drawing a Molecular Energy Orbital Diagram

In class we recently discussed how to draw out molecular orbital energy diagrams for compounds such as NH3 (ammonia). Building upon this, we touched on how to construct a molecular energy diagram for ...
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2answers
43 views

Equilibrium constant for complex cobalt ion

What is the equilibrium constant for the $\ce{Co(H2O)_6^{2+}(aq) + 4 Cl-(aq) <=> CoCl_4^{2-}(aq) + 6H2O(l)}$? I've looked at various sources but none seem to yield the actual equilibrium ...
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0answers
27 views

Shortcut method to find atomic term symbols ignoring the spin orbit coupling

Is there any shortcut method by which we can find the atomic term symbols ignoring the spin-orbit coupling, i.e. ignoring the values of J. For instance, when writing the d-d transitions for any ...
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How do we get the wave function of Ligand Group Orbitals with the same symmetry as that of the corresponding metal orbitals

In the book Principles of Structure and Reactivity by Huheey, Chapter 14, the author has taken linear combination of ligand orbitals to form ligand group orbitals and then further combination of LGOs(...
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1answer
41 views

N-heterocyclic carbene metal complexes. Question about the delocalization of the nitrogen lone pairs

I am wondering why nitrogen lone pairs are delocalized in NHC metal complexes. What I can think of is, when complex is formed, plus charge is formed on the carbon atom and therefore delocalization ...
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27 views

Aufbau's principle violation at the time of complex formation

My doubt is why don't we write 4s orbital before 3d as it is lower in energy according to Aufbau's principle? (I'm getting this info from other sites that 3d comes before 4s in transition metals but I'...
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Do species with more unpaired electrons attract magnets more strongly than those with fewer unpaired electrons?

My lecture notes state that you can distinguish between high spin and low spin complexes by their magnetic properties. This thought came to me: consider two octahedral crystal fields with a d7 ...
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Reference Request- good exercise book/reference material for ligand Field Theory? [duplicate]

Title. I currently own Problems in Molecular Orbital Theory and found it pretty helpful for my understanding, and was wondering if a similar book existed for ligand Field Theory (there is one chapter ...
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1answer
102 views

C4v point group complexes and the group orbitals (MO Theory)

Out of curiosity, what would the group orbitals be like in a C4v complex (square planar complexes or octahedral complexes with 5 identical ligands and 1 other) look like? I get a irreducible ...
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1answer
72 views

Is there a difference between a chelate ligand and a polydentate ligand?

I'm confused because my lecture notes state that chelate ligands are a subset of polydentate ligands.
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42 views

Are all ambidentate ligands monodentate?

Several websites define an ambidentate ligand as being monodentate. What about a ligand with say 3 atoms that can act as donor atoms, but due to the sterics of the ligand, only any two atoms can ...
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0answers
41 views

Is ammonium ion a positive ligand? If yes, please explain how does it coordinate with metal

In some books the examples for positive ligands are given as: $\ce{NO+}$, $\ce{NO2+}$, $\ce{NH2-NH3+}$, $\ce{NH4+}$, $\ce{H3O+}$, $\ce{PH4+}$. I can understand about the first three examples, but ...
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1answer
50 views

Aqueous copper and how it reacts with NH3

I have learnt that you can test whether an unknown metal is copper by doing a simple test tube reaction. The reaction involves adding aqueous $\ce{NH3}$ to the test tube which contains the copper. ...
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2answers
153 views

Is Fe(OH)2 soluble in alkalis?

I have just started inorganic chemistry in school and I have just learnt about metal aqua ions and how they react in water. I learnt that $\ce{[Fe(H2O)6]^2+}$ reacts in water by losing a $\ce{H+}$ ...
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29 views

ionisation isomers [closed]

With ionisation isomers, how do you know which ligand (out of $\ce{Br}$ and $\ce{NH3}$ for example) exchanges with the compound outside the bracket?
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1answer
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Distinguishing cis and trans positions

What I fail to understand is why does trans isomer contain $2$ $\ce{Cl}$ at axial positions but $2$ $\ce{NH3}$ are not taken to be so. Isn't the two $\ce{NH3}$ in the trans isomer in the picture cis ...
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1answer
55 views

Can superoxide ion act as a ligand in a similar fashion as peroxide?

There is a question in my chemistry book: Find oxidation state of platinum ion in the complex $\ce{[Pt(O2)(en)2Br]+}$. My books says that there is peroxide, but I want to ask why it is peroxide? ...
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Aqua complex scarcity for transition metal ions of second and third row

I've read that for the second and third row of the transition metal ions, almost no [M(OH$_2$)$_6$]$^{2+}$ or [M(OH$_2$)$_6$]$^{3+}$ complexes are known, while they're very common for the first row. ...
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26 views

My problem with Tollen's reagent [duplicate]

The formula of Tollen's reagent is $\ce{[Ag(NH3)2]+}$. What is the bond existing between the silver(I) atom and the ammonia groups? Because ammonia is stable, it doesn't need to gain or donate any ...
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98 views

Structure of (CH3COO)3Fe

I'm a grade 12 student trying to comprehend MOT & LFT in Co-ordination compounds. For one of our salt analysis(practicals), the test for acetate ion includes the addition of Neutral Ferric ...
2
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1answer
119 views

Why is carbon monoxide a monodentate ligand

Carbon monoxide has lone pairs on both the carbon and the oxygen atoms. However, I have never seen any complex where the oxygen atom or both the oxygen and the carbon atoms are the donors. I know ...
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163 views

Why does hydration enthalpy decreases instead of increasing down the group?

I have seen in my text book that for group 1 and 2 metals the hydration enthalpy decreases down the group.The reason I have found on the postWhich d-block cation has the maximum hydration enthalpy? is ...
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1answer
73 views

Why does ligand substitution occur when OH- is a better ligand than NH3?

$$\ce{[Cr(H2O)3(OH)3](s) + 6NH3 -> [Cr(NH3)6]^3+ + 3H2O + 3OH-}$$ When excess $\ce{NH3}$ is added to triaquatrihydroxychromium(III), why does ligand substitution occur when $\ce{OH-}$ is a better ...
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2answers
61 views

Vibronic coupling: How do I determine the new point group after vibration?

So I was recently discussing the transitions in Egyptian Blue ($\ce{CaCu[Si4O10]}$) with some of my students, who had to prepare this compound. What I like in particular in this case is how, at least ...
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2answers
103 views

What is the bond in H2O (water) molecule ? And why? [duplicate]

Is it covalent or coordinate covalent bond ? Because it can be a bond between O and 2 H atoms and so it will be covalent bond . And it can be a bond between H (+ve) ion and Oh(-ve)ion and it will be ...
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0answers
100 views

How to understand MO diagrams for cationic octahedral transition metal complexes

I am having problems understanding the construction of MO diagrams in octahedral transition metal complexes within ligand field theory (LFT) when the metal center is asumed as an cation: I am ...
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1answer
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How can I get create complex metal ion solution such that the majority of the central metal ions only have one specific ligand?

I'm looking for a way to have the ligand, Chloride ion, datively bond with Copper Sulphate. I understand it is as simple as creating a solution of Hydrochloric Acid and dissolving Copper Sulphate ...
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1answer
90 views

Second order Jahn-Teller effect for d0 complexes

I was wondering why the second order Jahn-Teller effect is also said to happen for many d0-systems? It makes sense to me that due to relativistic effects and the stabilization of the s-Orbital and ...
4
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1answer
98 views

Optical Isomerism in Coordination Compounds of type MA₂B₂(CC)

I was asked the following question: How many optical isomers are there for $\ce{[Cr(NH3)2Cl2(en)]^+}$ ? First of all I figured out the following four geometrical isomers of the above complex: Out ...
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1answer
36 views

UV Absorption of iodine with some solvent

$I_2$ in solution is typically absorbing around $525 \; nm$ this is why it appear to be magenta, I recently learn that with some solvent : Benzene Toluene $o$-Xylene $p$-Xylene The coordination ...
2
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0answers
153 views

Fluoride anion as a strong field ligand

In the case of $\ce{[Fe(H_2O)_6]^{3+}}$ there are $5$ unpaired electrons as water acts as a weak field ligand. But instead of flouride acting as a weak field ion in the $\ce{[MnF_6]^4-}$ , why does it ...
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1answer
281 views

Explain the structure of HNC (Hydrogen Isocyanide)

What are the different types of bonds present in the structure? Does Nitrogen donates one electron from its lone pair to carbon and acquires a positive charge? How do I determine the Oxidation state ...