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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4
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1answer
3k views

How can different no. of unpaired electrons lead to different colours of co-ordination compounds?

To make the question clear I would like to take an example. $\ce{K_3[Fe(CN)6]}$ and $\ce{K3[FeF6]}$ shows different colors in solutions. It is given in my textbook that it is because of different ...
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1answer
80 views

Does deprotonation of a hexaaquaion continue until neutral charge

I learned that deprotonation is the process in which a proton is lost from ligand $\ce{H2O}$ molecules surrounding a central metal ion (I am referring to hexaaqua ions). Also, the process continues ...
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2answers
33k views

Werner's theory and complex salts

According to Werner's theory, metal ions have two types of valency-primary and secondary, where the primary valency is said to be satisfied by negative ions only, and the secondary valency can be ...
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1answer
81 views

Does chelation take ions out of solution

Does EDTA take $\ce{Mg^{2+}}$ and $\ce{Mn^{2+}}$ out of solution, so that it can be removed by a filter? Or does it just take it out of any chemical reactions going on in the solution?
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3answers
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Hybridisation of Mn in potassium permanganate

I'm clear with the concepts of crystal field theory. But I can't figure out the exact reason why the hybridisation of manganese in potassium permanganate ($\ce{KMnO4}$) is $\mathrm{d^3s}$. Can anyone ...
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1answer
749 views

Which d-orbitals split according to CFT?

According to CFT, the degenerate d-orbitals split into $eg$ and $t_2 g$ groups. Are these the outermost nd orbitals which are vacant(4-d in case of 4th period) or the penultimate filled (n-1)d ...
6
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2answers
8k views

Why Cl⁻ can't act as bidentate ligand?

$\ce{Cl-}$ is a monodentate ligand. It has four lone pairs then why it can't donate two lone pairs to central atom and act as a bidentate ligand?
7
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1answer
1k views

Difference between sodium ion and a transition metal ion dissolving in water?

In class, I learned that when $\ce{NaCl}$ is dissolved in water, the partially negative oxygen part of the water molecules surround the $\ce{Na+}$ ion and energy is given off (hydration enthalpy) ...
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1answer
886 views

Formation of coordination complexes?

I'm having trouble understanding how exactly coordination complexes are formed. Compounds such as $\ce{[Cu(H2O)6]++}$ are the ligands filled into the empty 3 of 4p orbitals+ 1 of 5s orbital + 2 of ...
1
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1answer
903 views

If I add some KOH, where will the reaction shifts?

I just got a final test and one of the question is: $\ce {Ni^2+}$ + 6$\ce{NH_3}$ $\ce {<=>}$ $\ce{[Ni(NH3)6]^2+}$ If we add some aqueous $\ce{KOH}$ after the reaction reach equilibrium, where ...
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0answers
2k views

Magnetic moment of coordination complexes?

To understand the commonly quoted magnetic values of coordination complexes (central ion) we use $$m_l=\sqrt{n(n+2)} \text{BM where BM}=\frac{e\hbar}{2m_e}\text{JT}^{-1}$$ $n$=number of unpaired ...
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1answer
2k views

What is the number of unpaired electrons in cobalt(II) tetrathiocyanate?

Find the number of unpaired electrons present in the d orbital (whose lobes are present along the axis) for the complex $\ce{[Co(SCN)4]^{2-}}$. Since $\ce{{SCN}^{-}}$ is a weak ligand I did not pair ...
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2answers
1k views

Symmetry and stability of a molecule (Jahn-Teller Distortion)

I've taught in my class that if a molecule posses high degree of symmetry it's stability will be more,in other words symmetry and stability are directly proportional. Is this statement correct? And if ...
7
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3answers
103k views

How to calculate crystal field stabilisation energy?

How to calculate it? I know that it depends on the coordination compound and the number of electrons present in t2g and eg orbitals and the final answer is expressed in terms of crystal field ...
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6answers
11k views

Do ligands with a positive charge exist?

Are there positively charged ligands which can bind to a central metal atom to form coordination compounds? My thoughts: I know that ligands are Lewis bases which donate a pair of electrons, and the ...
9
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3answers
25k views

Is there a mnemonic to study the spectrochemical series?

Mnemonics help to by-heart things which are difficult to do so and which are important. I found mnemonics for studying the periodic table, electromagnetic series etc which were of great help. So, is ...
4
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1answer
713 views

Oxidation state of metal in metal oxo complexes always positive?

Do all metals in metal oxo complexes (eg $\ce{Fe}$ in Ferrate, $\ce{Mo}$ in $\ce{MoO4}$,...) have positive oxidation states?
7
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2answers
10k views

Optical isomerism in Co-ordination Compounds

Optical isomerism in normal organic molecules can be found out by looking for chiral carbon, and the number of isomers can be found out by drawing different spacial orientations of the same. But, I ...
2
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1answer
8k views

Difference between 18 electron rule and effective atomic number rule

Is there any difference between 18-electron rule and effective atomic number rule? Both rules are based on attainment of a noble gas configuraion as a criteria for stability of complexes. Besides, ...
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1answer
753 views

Geometrical Isomerism of Metal Complex

Does $\ce{Ni((en)2(Cl)2)}$ show cis-trans form ? And if No Why not ?
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1answer
784 views

What Could Formations of Linkage Isomers of [Co(NH₃)₅NO₂]²⁺ be like?

I am trying to draw the structure of this complex $\ce{[Co(NH3)5NO2]^{2+}},$ however I am not sure if the linkage isomers of this complex like this:
6
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1answer
354 views

Strongest chloride complex as predicted by HSAB theory

Why won't $\ce{Ni^2+}$ form a complex with $\ce{Cl-}$, while the ions $\ce{Cu^2+}$ and $\ce{Co^2+}$ form the complexes $\ce{[CuCl4]^2-}$ and $\ce{[CoCl4]^2-}$? According to the HSAB theory, $\ce{Cl-...
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1answer
1k views

Which d-orbital configurations form an octahedral complex?

With reference to crystal field splitting in octahedral complexes, my textbook shows the following table of distribution of $d$-orbital electrons in octahedral complexes, based on the energy ...
2
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1answer
733 views

Bonding in a bridged metal carbonyl

Can someone please explain the bonding in a bridged metal carbonyl (like diiron nonacarbonyl)? I cannot understand what kind of bonds (sigma/pi) exist between the bridging carbonyls and the metals. ...
14
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1answer
4k views

What does the eta notation mean in the naming of a transition metal complex?

I am reading a paper (Gutel et al., J. Mater. Chem. 2007, 17, 3290-3292) and I have come across the following reaction: In organic solvents, the decomposition under mild conditions of ($\eta^4$-1,...
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4answers
104k views

Tetrahedral or Square Planar

How can one predict whether a given complex ion will be square planar or tetrahedral when its coordination number is 4 using crystal field theory ? Is it possible to theoretically predict this?
6
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1answer
12k views

Normal Spinel and Inverse Spinel

According to my notes, octahedral site stabilization energy (OSSE), sterical effects and electronic effects in stability create a confusion in this theory. However, we are able to solve this problem ...
7
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3answers
17k views

Complexes formed by lanthanides and actinides

A very simple test for the presence of alcohols in the lab involves adding ceric(IV) ammonium nitrate solution which gives a pinkish red colour in the presence of alcohol. When I looked up the ...
11
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3answers
22k views

What is the meaning of '(en)'?

What is the meaning of $\ce{(en)}$ on this two coordination compounds: $\ce{[Co(en)_2(NO_2)_2]Cl}$ $\ce{[Cd(en)_2(CN)_2]}$ Is it a type of compound? If yes, what is the meaning?
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1answer
4k views

MO-Scheme of SCN- and its bonding properties when used as a ligand

I tried to figure out the MO-scheme of the tetragonal-bipyramidal complex trans-$\ce{[Co(en)2(NCS)2]SCN}$ in which the isothiocyanate ligands are bound to the $\ce{Co^3+}$-Ion in $\eta^{1}$-mode (en = ...
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2answers
4k views

How do copper sulphate and the like change crystal structure on adding water of hydration?

Copper sulphate, in its hydrated form, is crystalline, whereas the anhydrous form is amorphous. Gypsum has a similar story-- on heating the crystalline dihydrate we get an amorphous hemihydrate. (...
16
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2answers
300 views

What are the mechanisms for capture of As(III) and As(V) by magnetite from water?

Magnetite, $\ce{Fe3O4}$ is able to capture $\ce{As(III)}$ and $\ce{As(V)}$ from drinking water through the following mechanisms. Bidentate-binuclear complex Monodentate-binuclear complex (both from ...
7
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2answers
149 views

How to understand this form of writing the solution: (some salt • n H₂O)?

For example — "high purity chloride salt of Zinc $(\ce{ZnCl2.2H2O})$" or "various concentrations of $\ce{FeCl2.4H2O}$". What does the number before $\ce{H2O}$ mean?
53
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8answers
68k views

Is iron in the brown ring compound in a +1 oxidation state?

In the standard brown ring test for the nitrate ion, the brown ring complex is: $$\ce{[Fe(H2O)5(NO)]^{2+}}$$ In this compound, the nitrosyl ligand is positively charged, and iron is in a $+1$ ...
19
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1answer
652 views

Why does benzene bend in this reaction?

From here I can see why hapticity changes here, but not why it is necessary for the benzene ring to bend. The resonance energy of benzene is pretty large, and there's no balancing increase in ...
13
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2answers
452 views

Is aqueous medium necessary for complex formation? if so, why?

If dry ammonia gas is passed through anhydrous copper sulfate, will it turn blue (due to the formation of tetraamminecopper(II) complex)? Or will silver chloride form diamminesilver(I) complex in ...
25
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4answers
3k views

How may copper acetate ligands be manipulated to change colors?

I have a solution of copper acetate and I would like to play around with the ligands to get different colors. Background: The copper acetate was made through mixing vinegar (5% acetic acid), $\ce{...

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