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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. ...

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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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28 views

Major Species when EDTA Dissolves in Water [on hold]

If you add solid EDTA to water, what is the major species (cation, anion, or molecule other than solvent) in solution?
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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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29 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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25 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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Why is t2g level above eg level in octahedral d4 complexes in orgel diagram?

I am taking an introductory course in chemistry. This picture was there in my lectures, i am bit confused i thought the t2g level were lower than eg in presence of a weak octahedral field but it is ...
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57 views

Possible mechanism for thermal decomposition of potassium permangante

Recently, I came across this reaction: I was wondering if there is any logical way to propose a mechanism for this, preferably an arrow-pushing one?
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27 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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23 views

Oxidation number of complex compound

Consider a complex $\ce{K2[Cr(CN)2(O)2\color{red}{(O2)}(NH3)]}$ How would you find the oxidation number of the red ligand? I think that $\ce{(O2)}$ could mean dioxide, superoxide, or peroxide. How do ...
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74 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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45 views

Lewis acids as ligands

Usually Lewis bases as my textbook says: According to me its not compulsory for a ligand to be a Lewis base, as $\ce{BF3}$ is a Lewis acid and can act as a ligand by accepting electrons from a ...
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37 views

Is Hydrogen Bond a Coordinate Bond

My book here explains hydrogen bonding, just as we all know it, but also says that the electron deficient hydrogen atom and the oxygen atom of nearby molecule form a coordinate covalent bond as the ...
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42 views

How is Be(OH)4 Formed?

I recently did a test paper and the question stated that Be(OH)2 is amphoteric and so I was asked to write equations showing it both acting as an acid and a base. Acid answer: $\quad\ce{Be(OH)2 + 2H+...
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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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29 views

Axial bond angle in tris(ethylenediamine)copper(II) complex

In the tris(ethylenediamine)copper(II) complex - $\ce{[Cu(en)3]^{2+}}$ the axial bond angle is not exactly $\pu{180 ^\circ C}$ Is it because the at axial positions $\ce{Cu}$ is bonded using two ...
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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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29 views

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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25 views

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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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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Coordination number, or contact ion pair, or frequency number of potassium acetate

I need to have the experimental value of coordination number (= contact ion pair = frequency number) of aqueous potassium acetate. I have the number for KCL from the following article, but my efforts ...
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39 views

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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44 views

Nitrosyl complexes: oxidation state ambiguity

What is the oxidation state of chromium in $\ce{[Cr(NH3)(CN)4(NO)]^{2-}}$ ? Well if we assume $\ce{NO}$ to be bent that is $\ce{NO-}$, then oxidation state of chromium will be $\mathrm{+3}$. If we ...
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54 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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93 views

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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135 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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59 views

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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182 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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159 views

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 ...
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What reactions will occur at the anodes and electodes of two iron electrolytic cells?

What reactions will occur at the anodes and electrodes of two iron electrolytic cells: both with iron metal electrodes, one with an iron(II) sulphate electrolyte, the other with an iron(III) sulphate ...
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Will potassium oxalate form stable complexes with Al 3+ AND Fe 3+ in an acidic solution?

I am trying to perform a complexometric titration of both Al 3+ and Fe 3+ in a sulfuric acid solution. I would be measuring the titration using a thermistor. The goal in this would be to complex all ...
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163 views

Why is the oxidation state of Co -1 in [Co(CO)4]-?

In $\ce{[Co2(CO)8]}$, most people say the charge of $\ce{Co}$ is 0. How does it become $\ce{[Co(CO)4]-}$? Most answers would say that $\ce{Co}$'s charge becomes -1. How does this work? -1 is not ...
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67 views

What is an uninegative ligand

I can't find a simple definition via google. All I get are research papers, that I don't understand.
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Failure to Locate Stationary Point in GAMESS

I'm currently trying to optimize the geometry of a complex using GAMESS at the B3LYP level. However, I keep failing to converge the SCF. I've already tried the following: increasing the number of ...
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1answer
38 views

Ammonia complex [closed]

I am desperately trying to find an aqueous chemical that will selectively form a complex with ammonia gas. Any suggestions please? I am building a gas sensor for ammonia
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Is there anyway to derive the number of water molecules in a hydrated salt, given just the formula for the anhydrous salt?

Is there anyway to derive the number of water molecules in a hydrated salt, given just the formula for the anhydrous salt? That's pretty much it. If not, why? For coordinated water, my guess is ...
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109 views

Why or why not can hydroquinone and 2H-pyrrole act as ligands?

I want to understand why hydroquinone and 3H-pyrrole can or cannot act as ligands in transition metal complexes. If they are ligands, then what is their denticity? I'm trying to understand the ...
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142 views

Is there a theoretical way to predict the coordination number a metal can have in a complex? [closed]

We know that metals can form complexes with different coordination numbers, but I was told that certain metals have a greater probability to have a certain coordination number. But I was not able to ...
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83 views

What is the hybridization of iron pentacarbonyl?

What is the hybridization of $\ce{[Fe(CO)5]}$? Is this correct?
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202 views

Does the wavelength of light absorbed by a complex depend upon extent of splitting or stability?

Background: we were doing Crystal Field Theory in school when this question popped up. Specifically we were talking about stability obtained due to the chelate effect and if the extra stability in a ...
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Does the mixture of a ligand exchange reaction contain all the complexes obtained in the part reactions?

A ligand exchange reaction involves many part reactions. So, does the mixture contain all the complexes from those part reactions? Quoting an example from ChemGuide: This can be written as an ...
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103 views

Differences between hexaaqua cobalt (III) complex and hexammine cobalt (III) complex in aqueous solution

Why is $\ce{[Co(H2O)6]^3+}$ a strong oxidizing agent and $\ce{[Co(NH3)6]^3+}$ stable in Aqueous solution? I think this has got to do with Pairing Energy and Ligand strengths of $\ce{H_2O}$ and $\ce{...
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Do metal ions of 4d and 5d series always form low spin complex?

I've recently come across a source where it stated that all 4d and 5d metals form low spin complexes irrespective of the strength of ligand. I'm not sure of the authenticity of the source and couldn'...