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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45 views

What is the IUPAC name of [Cr(H2O)5Cl]Cl2.H2O

What is the IUPAC name of $\ce{[Cr(H2O)5Cl]Cl2.H2O}$? The net says that the correct name is Pentaaquachloridochromium(III) chloride. But do we not have to account for the water molecule present ...
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1answer
50 views

are there any stable four membered chelate rings?

With reference to coordination compounds, most chelate rings formed with the metal atom and ligands are 5-member rings (including the central metal atom), such as complexes with Oxalate, ...
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0answers
33 views

t2g and eg electronic configuration

I have been told that with the help of crystal field theory, we can decide the electronic configuration ($\mathrm{t_{{2g}}}$ $\mathrm{e_g}$ configuration) of the metal ion in a complex. For example, ...
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1answer
40 views

Will the following complex show optical isomerism

So there is this question which asks whether the following complex $\ce{[Co(NH3)4Br2]+}$ will show optical isomerism or not. According to my knowledge it will show optical isomerism in cis ...
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0answers
51 views

Is reverse transition is possible?

We have seen many times, especially in d-block, where an atom of d-block like $\ce{Cr}$ which has outer most atomic configuration as $4s^2$, $3d^4$, there will be a transfer of one electron from ...
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1answer
61 views

What is primary valency

This is from an adapted version of Concise Inorganic Chemistry by J.D Lee.The part on primary valency is confusing me.It mentions that primary valency is the oxidation of the central metal (a number) ,...
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1answer
49 views

Which hydrate isomer of [Cr(H2O)6]Cl3 have lowest electrical conductivity [closed]

I found this question in my book and the answer that was given is $\ce{[Cr(H_2O)_4 Cl_2]Cl.2H_2O}$ but I think it should be $\ce{[Cr(H_2O)_5 Cl]Cl_2.H_2O}$ because in this case only one $\ce{H_2O}$ ...
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1answer
155 views

Geometry of Ni(acac)2

The complex $\ce{Ni(acac)2}$ is paramagnetic as expected , i.e it has two unpaired electrons giving rise to a magnetic moment of $ \sqrt{8}$ BM but doesn't have the tetrahedral geometry consistent ...
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1answer
696 views

How does Potassium Hexfluoronickelate(IV) exist in a stable state?

Nickel generally does not exist in a $+4$ Oxidation state. Wikipedia has the following to say regarding Nickel(IV): Ni(IV) is present in the mixed oxide $\ce{BaNiO3}$. ....... Ni(IV) remains a rare ...
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2answers
72 views

Coordination number of chromium(III) oxalate complex

The coordination number refers to the number of binders that interact with the central metal ion. So, in the complex $\ce{[Cr(C2O4)3]^3-}$ chromium is bound to three oxalate ions. Why its ...
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1answer
516 views

How is the bonding in the [Au6C(PPh3)6]2+ cluster explained?

How can carbon form six bonds in such a compound as $\ce{[Au6C(PPh3)6]^2+}?$ I understand how carbon with five bonds can be formed $(\ce{CH5+},$ for instance), but it shouldn't have enough electrons ...
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1answer
74 views

What is the difference between cyanato, cyanido and cyano? When should i use which? [closed]

I understand that cyanido is the newly adopted naming in place of cyano but what is cyanato? Can anyone please give examples to illustrate the difference?
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104 views

Why is chromate coloured but tungstate colourless?

I have to try and work this out using the tetrahedral molecular orbital diagram for $\ce{[WO4]^2-}$ but I am confused as both are $\mathrm d^0$ right?
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Specific examples of all-main-group complexes with significant d-orbital contribution

It is usually said that d-orbitals are not usually used in bonding, even for so-called "hypervalent" ones, in compounds that are made purely of main group compounds. However, after reading an article ...
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1answer
69 views

Why is iron pentacarbonyl known, but iron(III) hexacarbonyl is not?

Why is the neutral complex $\ce{[Fe(CO)5]}$ known, but the cationic carbonyl complex $\ce{[Fe(CO)6]^3+}$ is not known?
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Predicting colors of aqueous solutions

While going through my AP chem prep book again, I came across questions asking about the color of certain aqueous solutions. For example: Which of the following substances will produce a colorless ...
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85 views

Definition of t2g orbitals in CFT

My textbook defines $\mathrm{t_{2g}}$ orbitals as $\mathrm{t_{2g}}$ stands for a set of three orbitals which are asymmetric with respect to $C_2$ axes, perpendicular to the highest $C_n$ axes, but ...
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3answers
159 views

Determining the oxidation state of a bridging platinum complex

I want to ask a question about determining the oxidation state of a Platinum complex. I was presented today with the following complex and asked to comment on the oxidation state and hence the d-...
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3answers
95 views

How to simplify these system of equilibrium equations

What is the pH when $0.025$ mol $\ce{NiCl2}$ is added to $\pu{1.00 L}$ of a $\pu{0.100 M}$ solution of $\ce{HCN}$, if the formation constant for $\ce{Ni(CN)4^2-}$ is $K_f=\pu{1.0e22}$, and the $K_a$ ...
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1answer
34 views

Optical activity of cis-trans isomers of a co-ordination compound [closed]

Why do geometrical (cis and trans) isomers of [Pt(NH3)(Br)(Cl)(py)] not show optical activity ? Thanks In Advance...
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25 views

Ion exchange resins

My problem is explained quite easily: I have no experience with ion exchange resins but I would like to test something out in order to exchange my sulfate ions in solution for nitrate (can also be ...
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1answer
32 views

Is specific rotation defined for mixtures of enantiomers or meso compounds?

I recently had to do an experiment where we had to make a racemic mixture of D and L complexes and then resolve the enantiomers, and measure the optical rotation of the racemic mixture, and the ...
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1answer
61 views

Triphenylphosphine (PPh3) vs. 1,2-bis(diphenylphosphino)ethane (dppe) ligand?

What about $\ce{NiCl2(dppe)}$ makes it a more efficient catalyst for Suzuki cross-coupling as opposed to $\ce{NiCl2(PPh3)2}$ or $\ce{NiCl2(PCy3)2}$? How does the dppe ligand increase the reactivity of ...
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What prevents inner-sphere electron transfer from oxalato-iron(II) to chloro-platinum(II)?

In this book (p. 237), when talking about the reduction of $\ce{[PtCl4]^{2-}}$ by $[\ce{(C2O4)2Fe]^{2-}}$, the author states that There is no easy route for imparting electrons onto the $\ce{PtCl4}^...
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Why does thiocyanate bind to Fe³⁺ with the S side instead of the N side?

According to hard and soft acids and bases (HSAB) theory, "soft" Lewis bases bind to "soft" Lewis acids, and "hard" Lewis bases bind to "hard" Lewis acids. $\ce{Fe^3+}$ is a hard Lewis acid. In $\ce{...
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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
27 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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21 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
37 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
53 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
304 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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44 views

Why is [NiCl2(PPh3)2] tetrahedral and [NiCl2(PMe3)2] square planar? [duplicate]

I'm confused here since PPh3 is a strong field ligand and would try to make the molecule square planar but is bulky and would tend to adopt tetrahedral geometry to minimise sterric hindrance. And why ...
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1answer
117 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
38 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
75 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(...
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32 views

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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0answers
60 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 ...
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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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0answers
39 views

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
70 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
118 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
119 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
174 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
102 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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0answers
34 views

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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0answers
34 views

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
62 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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108 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
66 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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