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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Hybridization of central atom in linear complexes

In Linear complexes (Like Diamminesilver(I)) what is the hybridization of the central metal atom ?(VBT) How will its crystal field splitting be like (CFT) ?
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Why doesn't the $5s$ orbital involve in $sp^{3}d^{2}$ hybridization?

Consider a co-ordinate complex like $[CoF_{6}]^{-3}$ for example. Here the hybridization is $sp^{3}d^{2}$ by the Valence Bond Theory, as illustrated also in this solution to a question on the same: I ...
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What do the boxes in an orbital diagram represent? [closed]

Now, online it says that s,p,d and f represent different orbitals. Ok, but when I searched what the boxes meant in the diagram for that orbital, I found out that each box is also an orbital with ...
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Equilibrium of zinc ion with ammonia

In my chemistry lab, we are testing the amphoteric properties of this metal. I understand zink can react with an acid or a base to form different compounds in solution based on pH. In one part of the ...
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In the aquation of cis-platin, why are the chloride ligands, and not ammonia, replaced with water, despite chloride's larger trans effect?

https://doi.org/10.1021/ic000847w In this paper, the aquation of cisplatin is examined. When used to treat cancer, the chlorides are substituted with water molecules, which seems to go against the ...
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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 ...
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Is [Fe(OH)(H2O)5]+ more likely to be oxidized than [Fe(H2O)6]2+?

I want to know if the $\ce{[Fe(OH)(H2O)5]+}$ ion formed upon adding water to $\ce{[Fe(H2O)6]^2+}$ is more likely to be oxidised to $\ce{Fe^3+}$ than $\ce{[Fe(H2O)6]^2+}$. If it is, then why?
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Difference between coordination compound and coordination complex [closed]

Hi can you tell me the difference between coordination compound and coordination complex? Define the two terms inorder to make the difference evident.
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Comparison of C=O bond strength in metal carbonyls

Find the weakest $\ce{C=O}$ bond among $\ce{[Mn(CO)6]+},$ $\ce{Fe[(CO)5]},$ $\ce{[Cr(CO)6]}$ and $\ce{[V(CO)6]-}.$ I thought the $\ce{C=O}$ bond strength would be lowest in $\ce{[V(CO)6]-}$ since the ...
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Maximum absorption wavelength directly proportional to the donor number of the ligand for a copper(II) coordination complex

I am looking at a set of results showing a directly proportional relationship for an increasing maximum absorption wavelength (UV-Vis spectra) with increasing donor number of solvent ligands. The ...
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Why is molar extinction coefficient for dithiocyanatobis(triphenylphosphine)nickel(II) so high?

I recently looked at a data set where $\ce{[Ni(SCN)2(PPh3)2]}$ had 0 unpaired electrons (from magnetic moment calculation) which indicated to me that it was square planar. I wondered how it could have ...
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Determining the number of triphenylphosphine ligands in nickel(II) complex

A complex is synthesised by combining hydrated solutions of $\ce{NiCl2}$ $(\pu{0.6 g})$ with $\pu{1.35 g}$ triphenylphosphine $(\ce{PPh3}).$ After cooling the product precipitates as a solid with ...
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Entropy and Gibbs Free Energy of Chelate Complexes

Of [Cd(NH2CH3)4]2+ and [Cd(en)2]2+ the stability of the latter is higher than the former attributing to chelation in the en complex .This is evident from the fact that the Gibbs Free Energy change for ...
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The complex [Cr(NH3)6]3+ is a high or low spin complex?

Why is it correct to say that this complex $\ce{[Cr(NH3)6]^3+}$ is a high spin complex? I thought it was a low spin complex because $\ce{NH3}$ is a strong ligand, but in an exercise, I have to explain ...
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Will the bond order of CO be greater in its existence as carbon monoxide or in metal carbonyl?

$$\text{Bond order} = \frac{N(b) - N(a)}{2}$$ Where $N(b)$ is the number of electrons in bonding orbitals and $N(a)$ is the number of electrons in antibonding orbitals. As in metal carbonyls, there is ...
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Comparing bond lengths in metal carbonyls

Question: It's solution is given as: Now I don't understand which d$\pi$ electrons have been considered here. For example, in $\ce{Fe(CO)_5}$, according to this, number of d$\pi$ electrons would be ...
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1answer
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Which of the following octahedral complexes absorbs the photon with the longest wavelength, λ?

I wonder which of the following absorbs photons with the longest wavelength, $\ce{[Cr(CN)6]^3-}$, $\ce{[Cr(SCN)6]^3-}$ and $\ce{[Cr(H2O)6]^3+}$. I know the one to absorb the highest wavelength should ...
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Is glycinate ligand a monoanion or a zwitterion?

Glycinate as far as I can guess from the structure is a monoanion with negative charge on oxygen atom (though that negative charge is resonating). But when I used this logic in my exam it costed me 4 ...
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Octahedral, Tetrahedral or Square planar? [closed]

In cases where a metal ion like, Fe(III), Cr(III), Pt(II) is made to react with a ligand species like oxalate, CN-, CO etc and it forms a complex then, How do we determine whether 6 ligands will be ...
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Why transition metal chloride complex have lower reduction potential than metal aqua ions?

Why transition metal chloride complex have lower reduction potential than metal aqua ions? For example: $$ \begin{align} \ce{Au^3+(aq) + 3 e- &-> Au(s)} &\quad E^\circ &= \pu{+1.52 V}\...
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1answer
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IUPAC name of H[AuCl4]

Is $\ce{H[AuCl4]}$ tetrachloroauric [III] acid or hydrogen tetrachloroaurate[III]? As per the rules I have studied the latter name is correct. Then why am I getting the former name mentioned ...
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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 ...
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Porphyrin Wheel Dynamic Ligand System

In the synthesis of a Porphyrin wheel detailed at the end, the researchers where able to add another ligand (a heterocyclic ligand) to a Porphyrin holding a metal ion. How is this possible when the ...
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Why is hydrated beryllium ion acidic?

The beryllium ion, $\ce{Be^{2+}}$, forms the aquo complex $\ce{[Be(H2O)4]^{2+}}$. According to LibreTexts, this complex is acidic in solution: $$\ce{[Be(H2O)4]^{2+} + H2O -> [Be(H2O)3OH]+ + H3O+}$$ ...
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Are high spin complexes and spin free complexes the same thing?

While solving some Coordination Compounds problems, I came across a problem that asked Select which complex is high spin or spin free octahedral complex. The term 'spin free' sounds like a complex ...
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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 ...
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How does the anti-bonding eg orbital (eg*) affect the bonding of ligands?

In the molecular orbital for octahedral metal-ligand complexes, there is an eg orbital and an eg* orbital. When the the d orbitals on the metal split, it will fill up some of the eg* orbitals I ...
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Why iron(II) spectrometry is not measured in distilled water and it requires a complexing agent like o-Phen?

We know that iron(II) ions in water have a green colour. Why we cannot draw the spectrum of iron(II) directly in distilled water to measure the absorbance then determine the concentration of iron(II)? ...
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Why does π-backbonding in a metal-carbonyl complex lead to a decrease in C-O bond strength?

I understand that π-backbonding in this complex involves the σ-donation of carbonyl to an empty d orbital of the metal, and the π-donation of the d electrons of the metal to the π* MO of the carbonyl. ...
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What exactly is hydrolysis? What are the products of hydrolysis of aluminium?

I came across three reactions while studying p-block compounds in inorganic chemistry. $$\ce{2Al + 2NaOH + 6H2O -> 2 Na[Al(OH)4] + 3H2} \label{eq:1} \tag{1}$$ $$\ce{Al2O3 + 2NaOH + 3H2O -> 2 Na[...
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EDTA titrations of singly charged cations

It is well known that EDTA can be used for titrations involving complexations of highly charged metal cations, with the most well known being those of the alkali earth metals and transition metals. ...
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Is the Co-ordination number of Cobalt always 6 in every co-ordination compound?

For example in the following compounds CoCl3.6H2O CoCl3.6NH3 CoCl3.5NH3 CoCl3.4NH3 in all of these complexes, we took the a)oxidation state of Cobalt as +3 ( since there are 3 Cl- ions and NH3 and ...
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Strength of Pi Donor and Acceptors as Ligands

The spectrochemical series is usually known as the "strength" of the ligands. It makes sense on a basic level as the more willing a ligand is to donating its electrons (via a $\sigma$-bond), ...
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1answer
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Are there square planar complexes with sp2d hybridization?

We were taught (Under the section 'Valence Bond Theory') seven types of geometries a transition metal complex may assume and its corresponding hybridization states, Linear - $\ce{sp}$ Trigonal planar ...
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Why are complexes of type MA3B3 not optical active?

Complexes of type $\ce{MA3B3}$ have two geometrical isomers, namely: fac-isomer mer-isomer If we look closely at the mer-isomer, it has a plane of symmetry, so it is optically inactive. But the fac-...
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Why isn't the orbital angular momentum also considered while calculating the magnetic moments 3d transition elements?

My textbook (Chapter: The d- and f- Block Elements) makes an interesting assertion, however, without any reason to back it up. Paramagnetism arises from the presence of unpaired electons, each such ...
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1answer
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Calculate EAN for [Fe(diars)2Cl2]Cl? [closed]

I know EFFECTIVE ATOMIC NUMBER (EAN) as the following • The sum of the number of electrons, donated by all ligands and those present on the central metal ion or atom in the complex is called an ...
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2answers
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How tetraamminecopper(II) is formed? [duplicate]

I'm trying to get a sense of how $\ce{Cu^2+}$ and $\ce{NH3}$ are bonded together because it doesn't make any! I understand that $\ce{NH3}$ has a lone pair of electrons that can be donated (right?), ...
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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 ...
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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 ...
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What are t2g and eg in CFT?

In the crystal field theory (CFT), when the splitting of the d-orbital occurs, it gets divided into two parts. The upper part with higher energy is the $\mathrm{e_g}$ and the lower part with lower ...
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Colours in Coordination Compounds

I have read that NH3 acts as an SFL with a M+3 metal ion and acts as a WFL with a M+2 metal ion. It also states that when NH3 forms a complex with the M+2 ion, its stability constant is 10^11. When ...
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Explanation of the orbital energies resulting from Jahn-Teller distortion of octahedral complex using MO theory

I am confused about the energies of the orbitals after Jahn-Teller distortion of an octahedral complex. Take elongation for example. To my understanding, since the ligands on the $z$ axis move away, ...
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Crystal field theory: splitting energy and stability

In crystal field theory, we admit that in a coordination compound there are only electrostatic interactions between the d orbitals of the central metal cation and the ligands (which are considered as ...
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2answers
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The colors that we see [closed]

I have a question. When I was studying Coordination Compounds, I came across this para: When a sample absorbs light, what we see is the sum of remaining colors that strikes our eyes. Observed and ...
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1answer
270 views

Is there an 'easy' way to determine if a ligand is a pi acceptor, donor or neutral?

First of all I am confused how something can be pi neutral? something either does or doesn't have filled p orbitals for example. given something I have never seen acting as a ligand before like ...
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1answer
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Bridging Hydride Covalent Model Electron Count - Hartwig

How can a bridging hydride be considered a 3 electron donor in the covalent model for electron counting? On page 3 of John Hartwig's "Organotransition metal chemistry" textbook [1], he lists ...
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1answer
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Determining direction of equilibrium

I am having a lot of trouble with this question. We have to determine if $K$ is greater or less than 1. I at first thought the equilibrium would favor the right side because this could have to do with ...
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Describe the formation of the [PbCl4]2- complex ion

The $\ce{[PbCl4]^{2-}}$ complex ion is formed when $\ce{PbCl2}$ is exposed to excess $Cl^-$ ions in solution as explained here and here through the following reversible reaction: $$\ce{PbCl2(s) + 2Cl^-...
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How to name Hg[Co(SCN)4]?

I have basically written the entire name except for the oxidation state of $\ce{Co}$. Mercury tetrathiocyanatocobaltate( ) to know what is the oxidation state of cobalt, I must know the ...

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