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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1answer
18 views

Can o-phenanthroline be used as a complexing agent for lead(II)?

I’ve been trying to find a method to perform a spectrophotometric analysis to determine lead concentration (on the ppm level). This would require some chelator capable of forming a coloured complex ...
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0answers
23 views

Formation constant of Eriochrome Black T Complexed with Pb (II) [closed]

What is Eriochrome black t’s formation constant when complexed with Pb (II)? If Eriochrome was placed in solution with a metal ion complexed to NH3, would Eriochrome likely replace NH3 via ligand ...
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0answers
39 views

Is [Co(H2O)6]3+ a low spin or high spin complex?

I had been taught that although $\ce{H2O}$ is normally a weak field ligand for 3d transition elements, $\ce{Co^{3+}}$ is an exception and forms a low spin complex with conventionally W.F.L. like $\ce{...
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Effect of optical isomerism on colour of transition metal complexes

I know that different stereoisomers of a given transition metal complex (cis- and trans- forms) have different colours. But do different optical isomers (non-superimposable mirror images) have ...
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1answer
47 views

Does tris(ethylenediamine)iron(III) exhibit optical isomerism? [closed]

I'm studying 12th. In my book they mentioned that $\ce{[Co(en)3]^3+}$ exhibits optical isomerism. But in that same book, there is a question Which of this doesn't exhibit isomerism? and the ...
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1answer
41 views

Is NH3 a strong ligand or weak? [closed]

Sometimes it produces high spin complex and sometimes low one. Is there any generalised result
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1answer
52 views

For group 13 elements M³⁺, why is the formation of MCl₄⁻ more favorable than for group 12 elements M²⁺?

I'm not a chemist and I'm trying to understand a chemistry point from a talk I went to recently. Any help would be much appreciated. The speaker was talking about $+3$ (Group 13) elements in the ...
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0answers
42 views

Why does the binding of DMSO to metal via the S atom (k-S) strengthens the S=O bond?

So, DMSO (dimethyl sulfoxide) can form metal complexes in both $\mathrm{\kappa O}$ and $\mathrm{\kappa S}$ mode i.e. binding with the oxygen or the sulfur respectively. The general explanation given ...
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2answers
197 views

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

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 ...
2
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1answer
56 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
50 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
47 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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1answer
90 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
90 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
203 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
702 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
116 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 ...
10
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1answer
537 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
129 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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1answer
119 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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0answers
23 views

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
108 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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2answers
177 views

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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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
188 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
98 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
38 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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0answers
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
38 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
72 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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0answers
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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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0answers
25 views

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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0answers
9 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
31 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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0answers
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
38 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
62 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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30 views

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
310 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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0answers
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
150 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
39 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
81 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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0answers
34 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
68 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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0answers
55 views

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
47 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
82 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
153 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
179 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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