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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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Co-ordination bond, Valence Bond Theory [on hold]

For Co(iii) ions when a weak ligand approaches (F), there is formation of sp³d² hybrid orbitals where only 2 d orbitals are going hybridisation, why can't all the 5 d orbitals participate in ...
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How do chelating ligands interact with metal orbitals?

How do ligands like acac and ox interact with metal d orbitals? I know both are pi donor ligands (weak field), so do they interact with the T2g set of orbitals?
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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
31 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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29 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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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
39 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
133 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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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
35 views

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
31 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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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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0answers
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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 ...
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1answer
72 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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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
59 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
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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
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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
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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
63 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 ...
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1answer
82 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
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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 ...
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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
143 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 ...
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1answer
182 views

Oxidation No. of Fe and NO in Nitroprusside ion [duplicate]

For the complex $\ce{[Fe(CN)5NO]^{2-}}$ wikipedia cites that the oxidation no. of Fe is +2 and that of NO is +1. CN being -1 the net charge thus becomes -2. However at certain places I read that NO is ...
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97 views

Hydrate isomerism

My book specifically mentions in the solution to a question: $\ce{[CrBrCl2 (H2O) (NH3)2].H2O}$ is not the hydrate isomer of $\ce{[CrCl2 (H2O)2 (NH3)2]Br}$ But the author hasn't provided any ...
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1answer
345 views

Bonding in Zeise's salt

I am not sure I completely understand the bonding in coordination compounds formed by donation of pi electron cloud by the ligands to the central atom. For example, consider Ziese's salt: I came ...
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1answer
80 views

Lewis acids as ligands

Usually Lewis bases as my textbook says: 2.3 Ligands The ligands are the ions or molecules bound to the central atom/ion in the coordination entity. This is better visualized as the combination ...
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Conformations in complex compounds with polydentate chelating ligands?

Does conformational Isomerism also occur in complex compounds where chelation occurs like in organic chemistry and if it happens is the stability order also similar like in Anti Staggered , skew , ...
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Inorganic IUPAC for Compounds with bridged ligands?

Can we use bis(tetraammine) instead of octaammine is the 2nd example ? As in the 1st example they used bis(pentaammine) and also in the 3 one the used bis(carbonylcyclopentadienyliron)
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Color change of aqueous ferric salt when reacted with phosphate

I have a question about an equilibrium system: $$\ce{Fe^3+ (aq) + SCN-(aq) <=> [Fe(SCN)]^2+ (aq)}\\ \text{(yellow)} \quad \text{(colorless)}\quad \qquad\text{(red)}\qquad\quad$$ The question ...
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Rhombohedral second-order Jahn–Teller effect in Au(II) complex?

I was recently listening to a talk about the following work[1] when the author mentioned that they explained the following. In this $\ce{Au(II)}$-porphyrin complex you observe two sets of $\ce{Au-N}$ ...
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Why are 5-ringed saturated chelates more stable than unsaturated ones while 6-ringed unsaturated chelates are more stable than saturated ones?

5-ringed saturated chelates seem to be more stable than unsaturated ones. On the other hand, 6-ringed unsaturated chelates are more stable than saturated ones. Why do these hold true?
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Why is the probability of a didentate ligand to form a chelate with a central atom, high?

When one ligating group of didentate ligands (like ethylenediamine) is coordinated with a central atom, then the probability of the other ligating group being coordinated, and hence forming a chelate, ...
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π-backbonding in tungsten complexes

I need to find in which of the following complexes the M-CO bond is stonger: [WO3(CO)3] and [W(CH3)3(CO)3]. According to my knowledge this is chiefly determined by the π-backbonding and how good ...
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Help understanding the pi-properties of the NCS- ligand

Course knowledge When considering the NCS- ion, I take all atoms to be sp hybridized. This means that there are 8 electrons that are accommodated in the $\pi$-system. There are two orthogonal 3-...
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1answer
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Is (Zn(OH)4)2- acidic or alkaline?

My chemistry teacher told me that $\ce{Al(OH)4^-}$, $\ce{Pb(OH)4^2-}$, $\ce{Zn(OH)4^2-}$ are called complex ions. So will they break down in some conditions and give out $\ce{OH-}$ to show alkaline ...
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Are crown ethers “recycled”, typically?

I know that crown ethers have the interesting property of strongly complexing alkali metals, which allows them to be used in organic solvents (eg. as "dissolving-activity enhancing agents" for ...
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1answer
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In Diazonium Ion why does N contain 4 bonds?

Nitrogen's valenc number is 3. Sometimes it can form a co-ordinate bond by donating it's lone pair electrons. In diazonium ion N has 4 bonds, then one of those 4 bonds must be a co-ordinate bond. ...
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Identification for qualitative analysis

The flow chart is indicative of a compound with a silver cation, because $\ce{Ag+}$ reacts with $\ce{I-}$ to form yellow $\ce{AgI}$. Since $\ce{Ag+}$ does not form a hydroxide complex, it forms the ...
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1answer
73 views

Why is there only one ionization isomer of [Cr(NH3)5(NO2)]Cl2?

How many isomers are possible for $\ce{[Cr(NH3)5(NO2)]Cl2}$? Consider all possible types of isomerism and draw each isomer. My texbooks presents only three possible isomers: $\ce{[Cr(NH3)5(NO2)]Cl2}$ ...
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Molecular orbital diagram for terminal metal-oxo complex with dative bonds

I am interested in terminal metal-oxo complexes and their electronic structure, specifically those with coordination numbers of 6, including the oxo ligand. I know that Fe(IV)-oxo complexes tend to ...
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1answer
446 views

Why is CO ligand higher than CN- in the spectrochemical series?

I've drawn MO diagrams for both molecules and they are isoelectronic. The main difference is that $\ce{C}$ is closer in electronegativity to $\ce{N}$ than it is to $\ce{O}$ so there will be less ...
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why do the complex [Cu(NH3)5NO2]SO4 show ionisation isomerism?

In ionisation isomerism, secondary valencies can be replaced by primary valencies on the condition that net charge going outside the coordination sphere must be equal to net charge coming inside it . ...
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234 views

IUPAC name of C₆(CH₃)₆²⁺

What is the correct IUPAC name (or least incorrect one, if the current rules can't precisely describe that) of the interesting species $\ce{[C6(CH3)6]^{2+}}$ (which is extensively discussed here), ...
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IUPAC nomenclature of chelates

I could finally get a copy of the Red Book 2005 from a library. In the chapter dedicated to nomenclature of coordinate complexes, while explaining the κ-system of specifying donor atoms, the following ...
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Cobalt Chloride in various solvent/water mixtures - tested

In a recent post the solvatochromic behaviour of cobalt chloride in acetone was discussed. There were some ideas how the acetone might influence the ratio between the blue $\ce{[CoCl4]^2-}$ and the ...
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1answer
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Considering the d-d transition how, does tetracyanidonickelate(II) ion exist as a colored complex?

As I refer on google, the resources indicated that, the d block elements which have unpaired electrons as in their ions, when they are making complexes with ligands, they can absorb different ...