A special class of compounds in which a electron deficient central atom (usually a metal ion) is bonded to many electron donors called ligands. These compounds are highly stable and are widely found in nature. They also have a wide variety of industrial applications.

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Can an atom bond with more than 8 other atoms?

Is it possible for an atom to bond with 8 other elements (same or other type)? If yes, then please give some examples. If no, then what could be the possible reason for it? Update + Edit: My question ...
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0answers
13 views

Why does the value of Δo increase with increased charge on the metal?

A greater positive charge means the ligand is strongly attracted and pulled closer, and thus it creates a stronger crystal field. The potential energy value of the barycentre should thus be higher, ...
3
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1answer
55 views
+100

Water exchange at Al (III)

Why is the rate of water exchange at Al(III) centres so slow ? According to this medical book (p.5) it is $10^{5}$ times faster at Mg(II).
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14 views

Methyl orange coordination compound chemistry

Methyl orange changes colors depending on the acidity or basicity of the solution. But I have read that it forms complexes with certain ions. Can anybody suggest any resource regarding the ...
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62 views

coordination chemistry and werners theory of complex compounds [on hold]

A solution containing 2.674 g of $\ce{CoCl3*6NH3}$ was passed through the cation exchanger. The eluted solution yields 4.305 g precipitate of $\ce{AgCl}$ with an $\ce{AgNO3}$solution. ...
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1answer
46 views

How to decide whether complex will be octahedral or tetrahedral? [on hold]

$\ce{Ni^{+2}}$ with $\ce{Cl-}$ is tetrahedral but with $\ce{H2O}$ the complex formed is octahedral, why?
4
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1answer
30 views

Nomenclature of complexes: Cyano vs Cyanido ; Chloro vs Chlorido

What is the correct nomenclature for $\ce{CN^-}$ and $\ce{Cl^-}$ ligands in coordination compounds? Wikipedia says the coding name(?) as cyanido and chlorido while this suggests cyano and chloro. ...
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0answers
19 views

Crystal field theory for calculating lattice parameters

If I have an 8-coordinated metal cation (e.g., $\ce{Te}$, $\ce{Nb}$, $\ce{Ta}$, $\ce{Sb}$, $\ce{Bi}$, $\ce{Zr}$, $\ce{Hf}$) by oxygen anions, is there a way to theoretically calculate the structure of ...
6
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1answer
41 views

In Crystal Field Theory what does Δo=10Dq mean?

While studying the Crystal Field Theory I was told $D_q$ is a unit, related to the unit $\Delta_{\mathrm{O}}$ by the relation $\Delta_{\mathrm{O}} = 10 D_q$. But aren't $\Delta_{\mathrm{O}}$ and $D_q$ ...
12
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2answers
369 views

What's so special about chelation? [duplicate]

There is another closely related post here , and I've also read the referenced wiki article including applications of chelation, but I still don't see what's so special about chelation. I understand ...
1
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0answers
39 views

Reaction between [Cu(NH3)6]2+ and NaOH

What type of reaction occurs between $\ce{[Cu(NH_3)_6]^{2+}}$ and $\ce{NaOH}$ and what are the products. And what happens when $\ce{NH_3}$ is evaporated from the product? can someone explain please.
3
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1answer
26 views

Determining spin of metal complex

Is there any way to determine the spin of $\ce{[Fe(OH)6]^{4-}}$ without looking at the spectrochemical series?
7
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1answer
59 views

Purpose of ammine in Tollens' reagent

In this previous question the mechanism for the reaction of Tollens' reagent was outlined. As I understand it the oxidising agent in Tollens' is the diamminesilver(I) complex $\ce{[Ag(NH3)2]+}$ but ...
4
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0answers
20 views

why is cobalt hexacyano complex uncommon?

In huheey they have written hexacyano cobalt(II) is uncommon but pentacyanoaqua cobalt (II) is common. They mentioned something about Jahn Teller distortion but I could not get the meaning
2
votes
1answer
72 views

High or low spin complex of Zn2+ and Ti3+

The zinc ion in its +2 state can show no more pairing, since all the electrons are already paired - so in any complex it forms it will have the same magnetic moment as it does right now. $\ce{Ti}$ in ...
11
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3answers
105 views

Why is ligand substitution only partial with copper(II) ions and ammonia?

When studying ligand substitution (at UK year 13 level), the following example has been given: \begin{align} \ce{[Cu(H2O)_6]^2+ + 2NH3 &<=> [Cu(OH)_2(H2O)_6] + 2NH4^+}\\ ...
7
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0answers
38 views

Oxo ligand molecular orbital diagram with metal center

With highly oxidizing metal center, we expect that the hydroxide ligand's proton becomes acidic and will be lost to the surrounding media, creating an oxo ligand. The oxo ligand is a $\pi$ basic ...
3
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23 views

Is hydrolytic polymerisation the mechanism by which the precipitate forms from the neutral complex?

From basic coordination chemistry and acid-base equilibria we understand that a metal hexa-aqua ion can be deprotonated until it's positive charge is balanced by the negative charge of the hydroxides ...
1
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1answer
41 views

Calculation of CFSE

I need to find CFSE for these: $\ce{[Ti(H2O)6]^3+}$, OK $\rm Ti$ is $\rm 4s^23d^2$, $\rm Ti^{3+}$ is $\rm 4s^03d^1$. Afterwards it becomes $\rm d^4sp^2$ or $\rm t_{2g}^5e_g^4$ so CFSE is ...
-4
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1answer
45 views

Reaction with silver oxalate?

I was asked which geometrical isomer of $\ce{[M(NH3)2Cl2]}$, viz. cis or trans would react with silver oxalate. The possible reaction could be formation of silver chloride but since the coordination ...
5
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1answer
64 views

Rate constants for water exchange

Are rate constants for water exchange of transition metal aqua-complexes tabulated anywhere ? I haven't been able to find a resource which is anywhere near comprehensive.
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0answers
55 views

Why [MnCl6]^2- has got 4 unpaired electrons instead of 3?

In $\ce{[MnCl_6]}^{2-}$, $\ce{Mn}$ has +4 oxidation state which gives it a $\ce{3d^3}$ $\ce{4s^0}$ configuration. But how is it having 4 unpaired electrons?
4
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2answers
60 views

Can any atom donate more than 1 lone pair as a coordinate bond to the same metal?

This would mean the formation of a sigma and one or two pi bonds, all coordinate. I haven't heard of this happening, like fluorine anion or water with 2 lone pairs on O will donate only one lone pair, ...
6
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1answer
54 views

How hydrate isomerism results difference in colours?

The standard example is $\ce{CrCl3.6H2O}$, which can have three distinctly different crystalline compounds now known as $\ce{[Cr(H2O)6]Cl3}$ (violet), $\ce{[CrCl(H2O)5]Cl .H2O}$ (blue-green), and ...
3
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1answer
100 views

What is the highest possible expanded octet?

Often called "hypervalent", chemicals like Phosphorous Pentachloride and Sulfur Hexaflouride are possible due to the fact that their central atoms form covalent bonds with more than four other atoms, ...
4
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1answer
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2
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24 views

Decomposition of hexaurea-chromic-chloride-trihydrate

I am sitting over a TG diagram of the decomposition steps of hexaurea-chromic-chloride-trihydrate ($\ce{[Cr(CO(NH2)2)6]Cl3 \cdot 3 H2O}$) and cannot really make sense of the products it might ...
1
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1answer
35 views

Changing solubility of metal complex by adding ethanol

After creating a solution of copper(II)-sulfate-pentahydrate, water and concentrated ammonia, the newly formed complex (tetraamminecopper(II)-sulfate-monohydrate) is completely dissolved in water. By ...
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0answers
12 views

Why Bari centre is considered as Zero energy level?

Why the degenerate energy level of d orbitals before forming complex is considered zero? what advantages are there for taking the mean of t2g and eg orbitals as zero?
2
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1answer
64 views

Does sodium form complexes like transition metal ions?

I realise that there is a similar question here Difference between sodium ion and a transition metal ion dissolving in water? and it seems to answer my question, however I was reading about how ...
1
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1answer
47 views

Iodine color change in different complexes

Why does the color of iodine differ when it forms a charge transfer complex with benzene (pi donor) - pink and ethanol (electron pair donor) - brown? Does the HOMO-LUMO energy differ, if so how?
0
votes
1answer
40 views

Why member ring is favoured in chelates?

why chelates which form 3 or 4 member rings or 6 or 7 member rings are as stable as 5 member ring chelates? for example if we measure stability of chelates with oxygen donors, say oxalate, malonate, ...
2
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1answer
38 views

what are possible isomers of (meso-stilbenediamine)(isobutylenediamine) palladium (II)?

It can form a square planar and a tetrahedral complex but within square planar or within tetrahedral can there be isomers possible?
1
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3answers
49 views

Does tetramine copper dissolve cellulose?

I saw a Youtube video which showed that cotton (cellulose) dissolves in deep blue solution of tetramine copper made by adding 20% ammonia in copper carbonate salt. I tried to replicate the process ...
2
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1answer
69 views

Why should a complexometric titration be kept neutral?

In my next lab, I'll be doing a complexometric titration of a copper solution with EDTA and a murexide indicator. The lab guide advises to keep the pH level nearly neutral by adding a diluted ...
1
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1answer
63 views

Ratio of copper(II) ions to EDTA?

One question in a test I am preparing for is: What is the ratio of copper(II) ions to EDTA in a $\ce{[Cu(EDTA)]^{2-}}$ complex? I know that EDTA forms up to 6 coordinate bonds with the central ...
4
votes
1answer
96 views

Why does Fe(CO)₄ adopt a tetrahedral, as opposed to square planar, geometry?

Why does $\ce{Fe(CO)4}$ adopt a tetrahedral, as opposed to square planar, geometry? Here's my analysis: Factors for square planar: coordination: 4 $\ce{Fe(0)}$: d8 $\ce{CO}$: strong field ligand ...
3
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1answer
29 views

Bipyridyl complex isomers

What type of stereoisomers do these two complex compounds represent?
2
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0answers
107 views

Why is inner orbital complex more stable than outer orbital complex?

I learnt that $\ce{Cr(II)}$ ion is a stronger reducing agent than $\ce{Fe(II)}$ In an aqueous solution as inner orbital complexes more stable than outer orbital complexes? I cannot understand why is ...
1
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1answer
29 views

Are there ways to fully dissociate a complex salt?

A complex salt is a salt where the metal and ligands do not dissociate in water. For eg : $\space\ce{K_4[Fe(CN)_6]}$ when put into $\space\ce{H_2O}$ dissociates as : $\space\ce{4K^+} + ...
2
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1answer
45 views

Why do electrons not get paired up in [Fe(H2O)5NO]2+?

The magnetic moment of [Fe(H2O)5NO]2+ is 3.87 Bohr magneton, which implies there are 3 unpaired electrons. Since iron is in +1 oxidation state (due to charge transfer with nitrosyl group), it's ...
1
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1answer
42 views

MO scheme for coordination complexes (tetrahedral) - Heteroligand vs. homoligand

How is the MO diagram drawn for a tetrahedral complex with heteroligands (e.g. $\ce{[NiCl2(PPh3)2]}$) different from a tetrahedral complex with the same type of ligand? Do we consider the same "a1 and ...
6
votes
1answer
138 views

Why is copper (II) coordination number so big?

Consider tetraaminecopper (II) ion. $\ce{[Cu(NH3)4]++}$ or $\ce{[Cu(NH3)4(H2O)2]++}$ Copper (II) ion has electron configuration $\ce{[Ar] 3d^9}$. How do the 4 electron pairs from ammonia atoms form ...
0
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0answers
29 views

Effect of radioactivity on bonding [duplicate]

What effect does $\alpha$ or $\beta$ decay have on the bonding in molecules? In particular the example I was thinking of was if you have a radioactive metal at the centre of a complex ion. I had a ...
5
votes
2answers
187 views

Is tetraammine dichloro cobalt (III) an optically active compound?

Is $$ \text{Co}[{(\text{N}{\text{H}}_{3})}_{4}{\text{Cl}}_{2}]$$ optically active? If so, write its stereo-isomers. I know that for a compound to be optically active, it should ...
1
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2answers
86 views

Why would there be differences in UV/Vis spectrum?

$\ce{[NEt4]2[NiBr4]}$ dissolved in $\ce{MeCN}$ and $\ce{[NEt4]2[NiBr4]}$ dissolved in $\ce{H2O}$ have different UV/visible spectra in the visible region. How would they differ, for example would one ...
0
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2answers
85 views

Thermogravimetric Analysis of hydrated compounds

I have been given this thermogravimetric analysis of my compound $\ce{NiBr2.$x$\,H2O}$ and I need to work out the number of moles of water in the complex. Also why are there two steps in the data?
2
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1answer
131 views

What does it mean in a Ni(II)complex if the HNMR spectrum appears unbroadened and unshifted & what does this tell you about the coordination geometry?

I am trying to work out the an unknown Ni(II) complex. I don't known the geometry and I have read that broad lines on the nmr spectrum indicate large compounds with symmetric environments. Does this ...
4
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2answers
127 views

Why does Cobalt have different coordination numbers in its complexes with water and thiocyanate?

I'd like to know why does cobalt(II), $\ce{Co^2+}$, form $\ce{[Co(H2O)6]^2+}$ complex with water while it forms $\ce{[Co(SCN)4]^2-}$ with the thiocyanate? Why is there $\ce{6H2O}$ but only $\ce{4 ...
3
votes
3answers
212 views

Are these reaction equations for the formation of the brown ring complex correct?

The above are the reactions given in my book for the qualitative analysis of nitrate ion (formation of the brown ring complex). I think that the reactions above are incorrect. The first one shows ...