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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19 views

Energy diagram of copper iodide complex

We did an experiment where copper iodide 4-methylpyridine and copper iodide imidazole was formed and now we are asked what orbital the electron is excited from and to. After much research we still ...
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1answer
50 views

Ligand substitution reaction in coordination compounds

I know that the following substitution reaction can take place: $$\ce{[Cu(H2O)4]^2+ (aq) + 4NH3 (aq) -> [Cu(NH3)4]^2+ (aq) + 4H2O (l)}$$ This is because ammonia is a stronger ligand than water. ...
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24 views

Benzannulation of 18-crown-6

I know crown ethers can be used to complex metal ions. Question: What important properties do 18-crown-6 change during the benzannulation from 18-crown-6 to DB18C6 (dibenzo-18-crown-6)? How do these ...
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1answer
55 views

Naming a coordination compound

I was asked to determine the coordination compound which has the name: $$\text{triamminetrinitritocobalt(I)}$$ I thought it must be: $$\ce{[Co(NH3)3(ONO)3]^2-}$$ The $-2$ charge can be deduced by ...
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1answer
215 views

Why is the solution of (NH4)2[Ce(NO3)6] used as an oxidizing agent? [closed]

In an MCQ, the correct statement regarding the abovementioned compound is that its solution is used as an oxidizing agent. I do not understand why that is so.
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Counterion exchange

I have a quick question about counterion exchange. I have this very practical problem at my hands that I have a ethyl sulfate $(\ce{EtSO4-})$ counterion for a $\ce{R4N+}$ moiety ($\ce{R}$ = 3 ...
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2answers
360 views

Chromium cyanide complexes

I have rarely seen any chromium $(\ce{Cr})$ square planar complexes and I have been told that $\ce{[Cr(CN)4]-}$ is tetrahedral. So, if the statement is actually correct, are there any other known ...
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1answer
680 views

Confused on how to draw cis-[Ni(H2O)4(NH3)2]Cl2 [closed]

I got a question on my practice exam telling me to draw cis-diamminetetraaquanickel(II) chloride, but I'm not sure on how to place the two $\ce{Cl}$ atoms.
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1answer
50 views

Isomerism and namegiving

Is this the right chemical formula of the $\ce{Rb[Pt(NH3)Br2Cl]}$ complex: rubidium amminedibromidochloridoplatinate(II)? And is it correct that it has geometric isomerism, being square planar with a ...
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1answer
127 views

Should we expect Jahn–Teller distortion in bis(ethylenediamine)nickel(II)?

(ii) The stepwise stability constants of the following complexes in aqueous solution at $\pu{25 °C}$ are given below: $$ \begin{array}{cll} \hline \ce{M} & \ce{[M(en)2(H2O)2]^2+} & \ce{[M(en)3]...
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Why do statistical effects impact stepwise stability constants?

I have a question regarding the stepwise stability constants of metal complex formation/substitution. My lecture notes say that if we have a metal complex, say $\ce{[MX_{6}]}$, and a substitution ...
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104 views

Stability order of chelate complexes of nickel and iron

Which stability order is correct? $\ce{[Ni(en)2]^2+} > \ce{[Ni(dmg)2]}$ $\ce{[Fe(edta)]^2-} > \ce{[Fe(en)3]^3+}$ In the first case I think the stability depends upon the strength of the ligand ...
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What is the order of crystal field stabilisation energy for tris(ethylenediamine)chromium(III) chloride and hexaaquachromium(III) chloride?

In my book it is given that the crystal field stabilisation energy for $\ce{[Cr(en)3]Cl3}$ is more than that of the complex $\ce{[Cr(H2O)6]Cl3}.$ By what I have studied, the crystal field ...
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Why CO is a weak pi-acid ligand?

This question was given by my chemistry professor, but I doubt that this question is not correct. Following the lewis definition of the acid, any molecule or atom acts as a acid if it accepts an ...
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1answer
509 views

Why is dimethylglyoximate a bidentate ligand and not a tetradentate ligand?

Why can't the 2 oxygen atoms donate a lone pair and hence become binding sites? Is it because of the angle made by the oxygen and Nitrogen atoms?
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1answer
539 views

Optical activity of cis coordination compounds

I came across a statement saying, "Consider a Octahedral coordination compound of type [MA2X2]. Then, if the compound is in a cis form, it shows optical activity as there is no plane of ...
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3answers
743 views

Which would have a more intense transition: a low spin d6 complex or a high spin d5 complex?

I have an assignment question for second year inorganic which asks to rank the intensity of d-d transitions for a number of complexes. Two are $\ce{[Fe(OH2)6]^3+}$ and $\ce{[Fe(CN)6]^4-}.$ Both will ...
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1answer
335 views

Ionization isomerism in coordination compounds

Ionization isomerism is defined as complexes which have same empirical formula but ionize to different ions in solution. Consider the complex $\ce{[Pt(NH3)4Cl2]I2}$. The other possible ionization ...
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2answers
285 views

Relation between the oxidation state of central atom and its coordination number in a complex compound? [closed]

We know for a complex say $\ce{[Co(NH3)3Cl3]}$ we have $\ce{Co^{3+}}$ and its coordination number here is 6. And for this if we know either oxidation state or coordination number then other is fixed. ...
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What's an appropriate ligand for Pd-Ag redox?

I want to reduce palladium with silver (in cellulose): $\ce{Pd^{2+} + 2Ag->2Ag+ +Pd}$. What is a good ligand and spectator ion for both metals? (The pH is not critical.) Ones I have considered: $\...
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Will disodium EDTA effectively destroy Tollens' reagent?

As I understand it, if I mix $\ce{[Ag(NH3)2]NO3}$ and $\ce{Na2EDTA}$ the silver will complex much more strongly with the EDTA than the ammonia, and the hydrogen ions will protonate the ammonia, ...
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1answer
253 views

Sulfate and carbonate ions as ligands

The pentahydrate salt of copper (II) sulfate exists as a blue solid while the anhydrous and monohydrate salts appear as white solids. The structures of these salts are discussed here. The blue colour ...
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383 views

Reaction between Sodium Thiosulfate and Iron Chloride

I'm doing a paper on catalytic effectiveness in this reaction, and am trying to identify how the catalysts are speeding up the reaction. Based on what I can find, $\ce{Fe}$ starts as $\ce{Fe^3+}$, ...
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1answer
294 views

About Fe(III) and Fe(II) coordination complexes

Why does Fe(III) form octahedral coordination complexes if it has 5 electrons in its d-orbitals? I understand that Fe(II) has 6 electrons in its d-orbitals and 6 lone pairs from 6 ligands as the 12 ...
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Explanation for why nickel turns green in hydrochloric acid

My daughter has a chemistry test that I am helping her prepare for. One question is Nickel sulfate, $\ce{NiSO4(aq)}$ is a green solution. Nickel chloride, $\ce{NiCl2(aq)},$ is a yellow solution. If ...
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1answer
157 views

Formation of green precipitation whilst adding potassium fluoride to aqueous solution of copper(II) sulfate [closed]

Aqueous copper sulfate solution (blue) gives a green precipitation with aqueous potassium fluoride. Explain these experimental results. I've read answers like, $\ce{H2O}$ is a weak ligand and ...
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1answer
836 views

Magnetic nature of tetraamminedichlorocobalt(III) chloride

I know how to predict magnetic nature when the compound contains only strong field or only weak field ligands. But in $\ce{[Co(NH3)4Cl2]Cl},$ $\ce{NH3}$ is a strong ligand whereas $\ce{Cl-}$ is a weak ...
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157 views

Changes in conductivity of CuSO4 solution after NH3 solution is added

In my high school chemistry class we are writing a lab. Originally, I wanted to measure the rate of a ligand exchange reaction at different temperatures by measuring changes in conductivity. After ...
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1answer
88 views

Is it important to use arrows as bonds in writing coordination compounds? [closed]

Why are the coordination compounds representated by arrows? Is it necessary to write every coordination compounds with the arrow side of the bond facing the metal ion and the other part the ligand?
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1answer
388 views

Why there are more examples of carbonylate anions than metal carbonyl cations?

I know that metal carbonyl complexes that do not follow EAN rule or 18 electron rule try to achieve that by gaining electron (forming carbonylate) or loosing electron (forming carbonyl cations). But ...
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1answer
102 views

Software that determines whether a molecule can exist and draw it from a formula?

I have run calculations that predict atomic configurations. As a simple example, in a system that contains H and O, I might get a list like: ...
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1answer
85 views

What is the binding mode of the ligand in complexes with quadruple metal-metal bonds?

I'm wondering which atomic orbital is left in a complex with quadruple metal-metal bond to bind the steric ligand, since all d orbitals except the x2-y2 are used for the metal-metal bonds? or is it ...
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90 views

Ce₂(SO₄)₃ solubility in water [duplicate]

I have mostly come across examples of solids whose solubility increases in liquids with an increase in temperature. However, there seem to be exceptions to generalized rule this such as the solubility ...
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923 views

Effect of Synergic Bonding on Bond Lengths in Metal Carbonyls

Consider the metal carbonyl, pentacarbonyl iron(0). There exists synergic bonding between the central metal atom, iron and the neutral carbonyl ligands. This strengthens the metal-ligand bond but ...
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284 views

Structure and oxidation state of bridging complexes

I am confused about the structure of bridging complexes with the bridging ligands as $\ce{OH-}$ or $\ce{NH2-}.$ Aren't they both monodentate ligands? And if they form a simple coordinate bond, then ...
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1answer
100 views

Does a complex that has no overall charge still have color?

The iron complex $\ce{[Fe(H2O)6]^2+}$ is colored but I'm wondering, if a pair of chloride ion is inserted on its secondary valency to form [FeCl2(H2O)6], does the complex loose its color or not?
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1answer
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Why does only the cis-isomer of potassium dioxalatodiaquochromate(III) form?

A friend of mine performed a standard synthesis reaction of potassium dioxalatodiaquochromate(III) by adding potassium dichromate to ethandioic acid dihydrate and a little water. The synthesis ...
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29 views

Why is it important to know the spin of bioinorganic complexes?

During a bioinorganic chemistry course, my teacher gives a lot of importance to spin states of metal ions and how they changes (or not) after the formation of a complex. For example, when hemoglobin'...
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0answers
60 views

How is Mn+7 in the Permanganate ion considered as momentarily reduced to +6 in LMCT? [duplicate]

I saw this passage on a book and it says that Ligand to Metal Charge Transfer (LMCT) overpowers d-d transitions thus the permanganate ion has an intense purple color. However, it was mentioned that ...
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80 views

Why does the hexachlorocopper(II) ion not form?

I am not entirely sure if this question has been answered before, but I was wondering why when copper forms a complex ion with chlorine there are only 4 chlorine ligands. I asked my teacher and he ...
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0answers
60 views

Determining geometry of coordination compund without experimental data [closed]

How can I determine if a coordination compound has a tetrahedral or square planar geometry without any experimental data (such as magnetic spin) by just looking at its formula? For example, what is ...
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1answer
1k views

Electronic configuration in [Ni(CN)4]2-

$\ce{[Ni(CN)4]^2-}$ is a low spin , inner orbital complex having $\mathrm{dsp^2}$ hybridisation. According to Crystal Field Theory, $\ce{CN^-}$ is a strong field ligand that causes pairing of ...
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1answer
296 views

Why is Polonium the only metal to crystallize forming Simple Cubic Cell?

I have read that Polonium is the only metal that crystallizes forming SCC. I searched for a concrete explanation but all they were saying is the stability of Polonium at STP. I can't really comprehend ...
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115 views

When H2NCH2CH2PH2 acts a monodentate ligand, it is the phosphine end that chelates. Why is that?

In some occasions, if the ligand acts on Pd it do so as a monodentate ligand. I am attempting to explain this phenomenon but came into a block.
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60 views

Does dichlorobis(triphenylphosphine)nickel(II) have a d⁰ electron count?

I am currently in dilemma because I'm trying to construct an octahedral splitting diagram for the $\ce{NiCl2(PPh3)2}$ complex. If the complex is $\mathrm{d^0}$ system, how would I determine whether ...
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1answer
2k views

What kind of isomerism does Ni(PPh3)2Cl2 have and what is their IUPAC name? [duplicate]

I know that there are 2 isomers that $\ce{Ni(PPh3)2Cl2}$ have and they exist in equilibrium. I am tempted to name them cis- and trans- but it does not sound right.
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1answer
67 views

What makes a compound basic? [closed]

Aluminum chlorohydrate is often referred to as basic aluminum chloride. The pH value of ACH is about 4. How is basicity in this context defined?
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2answers
203 views

Colour of metal complexes with the same type and number of ligands

Crystal Field Theory says that because of d-orbital splitting caused by different ligands we have 2 different energy levels for d-orbitals. It also says that transition metals are coloured because ...
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1answer
1k views

Products of the reaction between chromium(III) chloride, zinc and sulfuric acid

The aim of my experiment was to make a Cr(II) aquacomplex in situ, and for that I have the reaction: $$\ce{CrCl3·6H2O + Zn}$$ and I add concentrated sulfuric acid to it. I know that chromium(III) ...
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1answer
241 views

Horizontal symmetry plane of cis-dichloroosmiumtetracarbonyl

Consider the molecule $\ce{Os(CO)4Cl2}$ with a drawing given below via Chemtube3d: I thought in this molecule, if I drew a horizontal plane, then a $σ_\mathrm{h}$ would be present i.e. A ‘horizontal’ ...

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