Skip to main content

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.

215 questions with no upvoted or accepted answers
Filter by
Sorted by
Tagged with
10 votes
0 answers
631 views

Identifying alkyl ligands as π-donors or π-acceptors in transition metal complexes

Is there a systematic way to identify an alkyl ligand as a π-acceptor or π-donor in a transition metal complex? Although various sources indicate that the weak field ligands are typically π-donors and ...
doarfo's user avatar
  • 101
9 votes
0 answers
598 views

Cobalt Chloride in various solvent/water mixtures - tested

In a recent post the solvatochromic behaviour of cobalt chloride in acetone was discussed. There were some ideas how the acetone might influence the ratio between the blue $\ce{[CoCl4]^2-}$ and the ...
Justanotherchemist's user avatar
7 votes
0 answers
569 views

Does solvate isomers exist for coordination compounds with ammonia solvent as ligand?

I could find many sources confirming the hydrate isomerism(with water as solvent) but I couldn't find any information about any other solvent. In all the sources "hydrate/solvate isomerism" ...
Govind's user avatar
  • 318
6 votes
0 answers
435 views

How to explain oxidizing power from Molecular Orbital Theory

I am trying to explain the oxidizing property of $\ce{Fe^3+}$ in $\ce{H2O}$ and $\ce{CN^-}$ which is $\ce{[Fe(H2O)6]^3+}$ and $\ce{[Fe(CN)6]^3-}$. The electrochemical reactions along with their ...
Shira's user avatar
  • 451
6 votes
0 answers
2k views

Does fluoride anion ever act as a strong field ligand?

In the case of $\ce{[Fe(H2O)6]^3+}$ there are $5$ unpaired electrons as water acts as a weak field ligand. But instead of fluoride acting as a weak field ligand in the $\ce{[MnF6]^4-}$ , why does it ...
Som V. Tambe's user avatar
5 votes
1 answer
129 views

Is concept of weak and strong field ligands applicable in valence bond theory?

I study coordination chemistry at high school. I have read about valence bond theory (VBT) and crystal field theory (CFT) as well. My teacher taught me that VBT is based on the experimental values of ...
InfinityLies's user avatar
5 votes
0 answers
586 views

Explanation of the trans-effect (thermodynamic and kinetic) for octahedral transition metal complexes

The thermodynamic trans effect refers to the ground state weakening of the metal-ligand bond in a complex by a ligand trans to it. The kinetic trans effect is the lablisation of a ligand in a complex ...
S R Maiti's user avatar
  • 5,685
5 votes
0 answers
339 views

Why does beryllium have an exceptionally high hydration energy?

You would expect solubility of Group $2$ fluorides to increase down the group, as lattice energy plummets much more sharply than hydration energy does. For the most part, this is true: $\ce{BaF2}$ is ...
Ray Bradbury's user avatar
5 votes
0 answers
414 views

Interference of Ca-EDTA with fluoride delivery in mouthwash

The goal of fluoride mouthwash is to deliver $\ce{F-}$ to the surface of the teeth to turn hydroxyapatite in the dental enamel into fluorapatite. Typically sodium fluoride or stannous fluoride are ...
vodona's user avatar
  • 315
5 votes
0 answers
2k 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 ...
Aditya Sriram's user avatar
5 votes
0 answers
2k views

Why is hexacyanoferrate(II) colored and at the same time diamagnetic?

I am wondering why $\ce{[Fe(CN)6]^4-}$ is colored and at the same time diamagnetic. For a transition metal to be diamagnetic all the electrons should be paired up in the d orbitals and at the same ...
paul's user avatar
  • 75
5 votes
0 answers
1k views

Does the wavelength of light absorbed by a complex depend upon extent of splitting or stability?

Background: we were doing Crystal Field Theory in school when this question popped up. Specifically we were talking about stability obtained due to the chelate effect and if the extra stability in a ...
Shivay Vadhera's user avatar
5 votes
0 answers
652 views

Why do nitrogen molecules not act as ligands in haemoglobin?

Nitrogen molecules $(\ce{N2})$ have lone pairs, which, as far as I know, is the property of oxygen molecules $(\ce{O2})$ that allows them to act as ligands bonding to iron in haemoglobin in the blood. ...
Matt Whitelock's user avatar
5 votes
0 answers
51 views

Cytotoxicity of Ru-complexes

I have a basic question: why are Ru(II)-complexes cytotoxic? What I know is that depending on the used ligand some of them interact with the DNA either via DNA-pi-stacking (intercalation) or binding ...
V.Fly's user avatar
  • 51
5 votes
0 answers
3k views

Why is the geometry of tetracyanonickelate(II) square planar? Why is it colorless?

Why is the geometry of $\ce{[Ni(CN)4)]^2-}$ square planar given that it has a coordination number of 4? Shouldn't its geometry be tetrahedral as it would minimise the bond angle and hence repulsion? ...
bean's user avatar
  • 625
5 votes
0 answers
3k views

dsp2 and sp3 hybrid orbital shapes in coordination chemistry

Why is $\mathrm{dsp}^2$ square planar but $\mathrm{sp}^3$ tetrahedral in shape? I am unable to find a reason anywhere. I know how to figure which hybridisation a compound is, but not why.
Mahathi Vempati's user avatar
5 votes
0 answers
194 views

Effects on Stretching Frequencies in Organometallic Complexes

If you added a negative charge to $\ce{Mo(CO)_6}$ how would this effect the $\ce{CO}$ stretching frequency in an IR spectrum? My thoughts are that it would lower the $\ce{CO}$ stretching frequency ...
Lavvers's user avatar
  • 51
5 votes
0 answers
523 views

Possible causes for flawed results of an EDTA titration for the Ca content of milk

Earlier today I was trying to find the calcium content of different milks as a part of a school assignment. I used this setup as the basis for my experiment: I was using $\pu{0.1 M}$ EDTA solution ...
Bruno KM's user avatar
  • 163
5 votes
1 answer
13k views

Inorganic IUPAC for Compounds with bridged ligands?

Can we use bis(tetraammine) instead of octaammine is the 2nd example ? As in the 1st example they used bis(pentaammine) and also in the 3 one the used bis(carbonylcyclopentadienyliron)
Chloritone_360's user avatar
5 votes
1 answer
3k views

Why can't oxalate ion donate two pairs of electrons from the two double-bonded oxygen atoms

So, I read that an oxalate ion is a bidentate ligand but since I saw that it has 4 oxygen atoms I was confused as to why it isn't a tetradentate ligand instead. I searched it on Google and found this:...
HeWhoMustBeNamed's user avatar
4 votes
0 answers
191 views

Ferrocene's band gap is supposed to make it colorless but it isn't. Why is it so?

Wang and Islam [1] state that the ferrocene molecule's band gap, i.e. the HOMO-LUMO gap at the Kohn-Sham level, is 5.03 eV, which corresponds to an absorption wavelength of at most 240 nm. So, ...
Kanghun Kim's user avatar
4 votes
0 answers
80 views

Do Metal Carbonyl complexes exhibit multiple back donation at the same time?

I came across a question which renewed one of my doubts that I had regarding bonding in metal Carbonyl complexes. According to me, metal should exhibit multiple back donation at the same time. ...
Rishi's user avatar
  • 477
4 votes
0 answers
116 views

How to use Sodium Thiosulfate for fixing dicopper (I) tetraiodomercurate (II)?

DISCLAIMER DO NOT TRY TO DEMERCURATE USING DESCRIBED PROCEDURE. CONSULT YOUR EMERGENCY SERVICE. I found a discrepancy between a government-approved procedure of living quarters demercuration and the ...
AntonPeganov's user avatar
4 votes
0 answers
129 views

Metal coordination in enzymes: What type and number of bonds form between amino acid residues and Fe(II)?

My understanding: Transition (d-block) metals, as found in intracellular proteins, are limited to about 10 elements including amongst others Fe, Ni, and Cu. Due to the reductive environments inside ...
CuriousTree's user avatar
4 votes
0 answers
2k views

Protonated forms of EDTA and their constants of formation with metal ions

It is widely known that the fully deprotonated form of EDTA (usually written as Y4-) is the only form that is significantly involved in complexation reactions. From what I have read, this accounts for ...
TheRelentlessNucleophile's user avatar
4 votes
0 answers
81 views

Rhombohedral second-order Jahn–Teller effect in Au(II) complex?

I was recently listening to a talk about the following work[1] when the author mentioned that they explained the following. In this $\ce{Au(II)}$-porphyrin complex you observe two sets of $\ce{Au-N}$ ...
Justanotherchemist's user avatar
4 votes
0 answers
3k views

Help understanding the pi-properties of the NCS- ligand

Course knowledge When considering the NCS- ion, I take all atoms to be sp hybridized. This means that there are 8 electrons that are accommodated in the $\pi$-system. There are two orthogonal 3-...
chemistrystudent's user avatar
4 votes
0 answers
71 views

Is there anyway to derive the number of water molecules in a hydrated salt, given just the formula for the anhydrous salt?

Is there anyway to derive the number of water molecules in a hydrated salt, given just the formula for the anhydrous salt? That's pretty much it. If not, why? For coordinated water, my guess is ...
Varad Mahashabde's user avatar
4 votes
0 answers
449 views

Differences between hexaaqua cobalt (III) complex and hexammine cobalt (III) complex in aqueous solution

Why is $\ce{[Co(H2O)6]^3+}$ a strong oxidizing agent and $\ce{[Co(NH3)6]^3+}$ stable in Aqueous solution? I think this has got to do with Pairing Energy and Ligand strengths of $\ce{H_2O}$ and $\ce{...
Sid's user avatar
  • 200
4 votes
0 answers
142 views

π-ligands in trigonal prismatic complexes

We recently had a discussion here about the symmetry problems for the often postulated s- and p-mixing with the d-orbitals in complexes to somehow allow a d-d-transition. It was pointed out back then ...
Justanotherchemist's user avatar
4 votes
0 answers
277 views

Why does the electrolyte used in Lechlanché cell turn blue?

In my school there are jars which are turned into Lechlanché cells. Basically the cell has aqueous ammonium chloride solution as the electrolyte which is obviously transparent in the beginning. The ...
Kartikeya Badola's user avatar
4 votes
0 answers
296 views

What will happen if ligand orientation is changed?

How we came to know ligand should approach from t2g orbitals in d5 configuration for tetrahedral complexes? What will be the difference in energy if ligand approach from eg? As far as I can think, ...
Aditya Shrivastava's user avatar
4 votes
0 answers
398 views

Precise explanation of macrocyclic effect

In most of the books, the reason of macrocyclic effect is given that It occurs due to preorganised structure of macro-cyclic ligand.  But a proper explanation of these two particular examples isn't ...
Aditya Shrivastava's user avatar
4 votes
1 answer
439 views

Crystal field splitting pattern with strong field and weak field ligands

What will be crystal field splitting pattern for octahedral complexes if some of the ligands are strong and some are weak field ligands?
Subhadip Pal's user avatar
3 votes
0 answers
27 views

What prevents an octahedral complex from always assuming the quadratic planar limiting case, due to the Jahn–Teller distortion?

When a given high-spin complex is Jahn–Teller distorted, this does not change the relative position of the total energy of the complex (assuming $\mathrm{d^{10}}$ configuration). Indeed, the ...
Rivinius's user avatar
3 votes
0 answers
58 views

Is aqua-meth-myoglobin (Fe3+) paramagnetic?

Is aqua-meth-myoglobin (Fe3+) paramagnetic? In this case, the iron has all 6 coordination positions occupied by ligands: 4 nitrogen atoms from the pyrrolic rings that compose the porphyrin, 1 ...
Arthur.chem's user avatar
3 votes
0 answers
68 views

Energy of d(x²-y²) and d(xy) orbitals the same with respect to trigonal symmetry?

In the orbital splitting diagrams of trigonal planar and trigonal bipyramidal complexes the d$_{x² - y²}$ and d$_{xy}$ orbitals have the same energy. I have always assumed that this is because they ...
Dion Silverman's user avatar
3 votes
0 answers
194 views

Why does Co(CO)4 exist as dimeric Co2(CO)8?

I was wondering why is this equilibrium below established at all... Why can't Co(CO)4 exist on its own, as a monomer?
Rudransh Sinha's user avatar
3 votes
0 answers
50 views

Electron count of complexes

For counting the electrons of the complex (RO)3W≡CMe, the book considers three RO- groups that donate a total of 10 electrons and it regards ≡CMe as [carbyne]- group in the ionic model and has a total ...
Cindy's user avatar
  • 31
3 votes
0 answers
88 views

Why doesn't Mn2+ ion form ammine complexes in aqeous medium?

Cations of 3d- elements particularly, the last four ones such as Cu2+ Zn2+ Co2+/Co3+and Ni2+ form metal-ammine complexes readily in aqeous solution, while the cations Mn2+ Cr3+ and Fe3+ usually dont. ...
Sudhagar's user avatar
  • 131
3 votes
0 answers
79 views

Why is hexacyanoferrate(II) coloured whereas tetrachlorocadmiate(II) is not, even though both lack unpaired electrons?

$\ce{K4[Fe(CN)6]}$ is coloured whereas $\ce{Na2[CdCl4]}$ is not. Even Laporte selection rule would suggest the tetrahedral cadmium complex to have a higher intensity of colour than the octahedral iron ...
Confused's user avatar
3 votes
0 answers
140 views

Can proton NMR be used to study transition metal complexes?

I prepared metal complexes with a Schiff base ligand L using cobalt(II) chloride hexahydrate, iron(III) chloride hexahydrate, and nickel(II) nitrate hexahydrate. I used 1H NMR to study the difference ...
Sunita's user avatar
  • 51
3 votes
0 answers
180 views

Can denticity and hapticity be defined simulaneously for a ligand?

I am freshly studying coordination chemistry. What I understand from denticity and hapticity is: Denticity - no. of electron donating sites in a ligand. Hapticity - no. of electron donating atoms in a ...
Fundamental's user avatar
3 votes
0 answers
89 views

Action of Fuller's Earth on Marble and Limestone

Using Fuller's earth is a very common and harmless way to treat marble and limestone that has been damaged/corroded by atmostpheric pollutants such as PM2.5/PM10 carbon particles (Soot) , Oxides of ...
pyramiskyma's user avatar
3 votes
0 answers
87 views

My EDTA titration isn't giving the right titre

I am, as a fun off-syllabus investigation, looking at hard water and how effective the EDTA titration method is, for permanent and temporary hard water. I ran a titration today and had horrific ...
Kay's user avatar
  • 31
3 votes
0 answers
58 views

Why can zinc porphyrins assume 5 coordinate geometries?

It has been reported that 5-coordinate geometries are possible and stable for Zn(II) porphyrin complexes. How do these complexes form and why are they stable when other 5-coordinate geometries of Zn(...
Tiocfaidh's user avatar
  • 131
3 votes
0 answers
141 views

Why is tetrachlorocuprate (II) yellow if it is high-spin?

From my knowledge of transition metal complexes, tetrahedral complexes generally have less splitting (compared to octahedral complexes) because they only involve four ligands are they aren't placed ...
chematwork's user avatar
3 votes
0 answers
300 views

Which acetate salt is blue and turns yellow when dissolved in water?

***Update Some questions I am considering to try to answer this question; When dissolving the powder in acetic acid, which ions are present? From what I've read, I haven't found any acetate salts ...
XisUnknown's user avatar
3 votes
0 answers
415 views

How is the UV-visible spectra of carbonatotetraamminecobalt(III) nitrate interpreted?

In a laboratory practice I have done a characterization of the $\ce{[Co(NH3)4CO3]NO3}$ and obtained the following spectra: I don't know if the band between 300 nm and 400 nm can be due to the effect ...
Enric Ros's user avatar
3 votes
0 answers
511 views

When is ammonia and water a strong ligand?

While studying the spectrochemical series, my sir said that as ammonia and water lie in the center, their behaviour as a ligand is tough to judge. For example if we have CO as a ligand, we know that ...
user95979's user avatar

1
2 3 4 5