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.

Filter by
Sorted by
Tagged with
9
votes
2answers
4k views

Why do copper (II) complexes contain so many valence electrons?

Consider tetraaminecopper (II) ion. $\ce{[Cu(NH3)4]^2+}$ or $\ce{[Cu(NH3)4(H2O)2]^2+}$. The copper(II) ion has the electron configuration $\mathrm{[Ar]\ 3d^9}$. How do the 4 electron pairs from the ...
6
votes
2answers
11k views

Is tetraammine dichloro cobalt (III) an optically active compound?

Is $$ \text{Co}[{(\text{N}{\text{H}}_{3})}_{4}{\text{Cl}}_{2}]$$ optically active? If so, write its stereo-isomers. I know that for a compound to be optically active, it should rotate the plane of ...
1
vote
2answers
203 views

Why would there be differences in UV/Vis spectrum?

$\ce{[NEt4]2[NiBr4]}$ dissolved in $\ce{MeCN}$ and $\ce{[NEt4]2[NiBr4]}$ dissolved in $\ce{H2O}$ have different UV/visible spectra in the visible region. How would they differ, for example would one ...
1
vote
2answers
1k views

Thermogravimetric Analysis of hydrated compounds

I have been given this thermogravimetric analysis of my compound $\ce{NiBr2.$x$\,H2O}$ and I need to work out the number of moles of water in the complex. Also why are there two steps in the data?
2
votes
1answer
666 views

What does it mean in a Ni(II)complex if the HNMR spectrum appears unbroadened and unshifted & what does this tell you about the coordination geometry?

I am trying to work out the an unknown Ni(II) complex. I don't known the geometry and I have read that broad lines on the nmr spectrum indicate large compounds with symmetric environments. Does this ...
10
votes
2answers
201 views

Bonds within complex anions

Many groups of bound atoms complexively bearing a (negative) charge are called complex anions. Examples are $\ce{NO3-}$, $\ce{CO3^2-}$, $\ce{BO3^2-}$, $\ce{CrO4^2-}$, $\ce{Cr2O7^2-}$, $\ce{MoO4^2-}$, $...
1
vote
2answers
3k views

Potassium thiocyanate and iron(II) acetate

I am trying to find the net-ionic equation for the reaction of potassium thiocyanate and iron(II) acetate. It seems reasonable to me that the molecular equation is $$\ce{2KSCN + Fe(CH3COO)2 -> ...
8
votes
1answer
4k views

Why is pyridine a monodentate ligand, but pyrrole a tridentate ligand?

Is it correct to say pyridine’s non-bonding electron pair does not participate in electron resonance while pyrrole’s non-bond electron participates in electron resonance? Would therefore pyridine’s ...
5
votes
2answers
4k views

Why does Cobalt have different coordination numbers in its complexes with water and thiocyanate?

I'd like to know why does cobalt(II), $\ce{Co^2+}$, form $\ce{[Co(H2O)6]^2+}$ complex with water while it forms $\ce{[Co(SCN)4]^2-}$ with the thiocyanate? Why is there $\ce{6H2O}$ but only $\ce{4 ...
6
votes
3answers
12k views

Are these reaction equations for the formation of the brown ring complex correct?

\begin{align} \ce{NO3- + 3Fe^2+ + 4H+ &-> NO + 3Fe^3+ + 2H2O}\tag{1}\\ \ce{[Fe(H2O)6]^2+ + NO &-> \underset{\text{(brown)}}{[Fe(H2O)5(NO)]^2+} + H2O}\tag{2} \end{align} The above are ...
1
vote
1answer
13k views

How do I find the oxidation number of a coordination complex

I actually know how to calculate the oxidation number for coordination complexes but some complexes like the below are giving some reistance $\ce{[Cu(NH3)_2][Fe(H2O)_3]}$ (diamminecopper(?) ...
1
vote
1answer
589 views

Dimers and polymers of electron deficient compounds

Why does $\ce{BeH2}$ polymerize into $\ce{(BeH2)_{n}}$ in solid state whereas $\ce{AlCl3}$ dimerises into $\ce{Al2Cl6}$ in the vapour state ?
5
votes
3answers
5k views

Why is tetracyanonickelate square planar?

Why is tetracyanonickelate, $\ce{[Ni(CN)4]^{2-}}$ square planar? $\ce{CN}$, for being a strong field, would not follow Hund's rule. the central atom $\ce{Ni}$ would have a +2 charge so its ...
2
votes
1answer
4k views

Magnetic moments of tetrahedral Cobalt (II) and (III) complexes

From the spin-only formula we can predict that for tetrahedral cobalt (II) complexes $$m_{eff} = 3.87 \mu_B $$ This ignores orbital angular momentum effects, which result in higher magnetic moments ...
2
votes
1answer
3k views

Cu2+ octahedral complexes

$\ce{Cu}^{2+}$ has nine d-electrons, regardless of the ligand field strength it will have one free electron (so it is paramagnetic. Are $\ce{Cu}^{2+}$ octahedral complexes high spin or low spin?
4
votes
1answer
7k views

Why are square planar coordination compounds with four different ligands optically inactive?

Why do square planar coordination compounds of type $\ce{[Mabcd]}$ not show optical activity, although they contain 4 different ligands (i.e. chiral central metal atom)?
1
vote
1answer
48 views

Which ligands would be exchanged in this reaction?

I have this reaction and need to state what the products would be: $\ce{(CF3)2PH + [W(CO)5(THF)] -> }$ THF stands for Tetrahydrofuran. Would this just be a simple ligand exchange, and if so ...
0
votes
1answer
435 views

Absorbtion of light by a coordination compound

A $\ce{[M(H2O)6]^2+}$ complex typically absorbs at around $600\ \mathrm{nm}$. It is allowed to form a new complex $\ce{[M(NH3)6]^2+}$ that should have absorbtion at? The absorbtion is because of ...
22
votes
1answer
76k views

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 ...
12
votes
1answer
28k views

Why are d-d electronic transitions forbidden and weakly absorbing? Why do they occur at all?

I am unable to understand why d-d electronic transitions are forbidden? Why are they weakly absorbing and apart from that, why do they occur at all?
5
votes
2answers
3k views

How many different possible structures (isomers) are there for the complex, [Mn(OH2)3(NH3)3] 3+?

How many different possible structures (isomers) are there for the complex, $\ce{[Mn(OH2)3(NH3)3]^{3+}}$? I really don't know how to begin with this. I know the answer is 2, but i don't have the ...
7
votes
2answers
67k views

Why does Co2+ have 7 electrons in the 3d orbital, and not 5 like Mn?

I'm taking general chemistry 2 this half of the summer. We are currently going over coordination complexes, ligands and transition metal ions. In particular, this question is in regards to the ligand ...
1
vote
1answer
1k views

How many ligands in Heme?

How many ligands does Fe has in heme ? I am not sure how many are in heme and how many in cytochrome C. Its about iron complexes.
-1
votes
1answer
330 views

How is square planar geometry possible in metal complexes?

I came across this statement and I don't understand what it meant by it: "Square planar geometry is favoured by ligands that can form pi bonds by accepting electrons from metal atoms or ions." How ...
1
vote
2answers
3k views

What is the coordination number for BeCl2?

I am confused, should it be 2 or 4? If I consider $\ce{BeCl2}$ as a chain structure the coordination number is 4, and in the gas phase it is 2.
4
votes
1answer
200 views

Electride salt preparation

In preparation for the Birch reduction, I am trying to prepare an electride salt, $\ce{[Na(NH3)6]+, e-}.$ This salt should be brilliant blue, as far as I know, but I am getting a black sludge when ...
10
votes
1answer
1k views

Inorganic chemistry reaction mechanisms

Are there well developed reaction mechanisms in inorganic chemistry like those in organic chemistry? If yes, please suggest an easy to follow reference.
2
votes
1answer
4k views

Which d-block cation has the maximum hydration enthalpy?

Among $\ce{Mn^2+}$, $\ce{V^2+}$, $\ce{Ni^2+}$ and $\ce{Ti^2+}$, which cation is having the highest hydration energy to form the aqua complex $\ce{[M(H2O)6]^2+}$? I guess $\ce{Mn^2+}$ should be the ...
12
votes
1answer
598 views

What is the Structure of FeSO₄ • NO?

What is the structure of $\ce{FeSO4 \cdot NO}$ that is formed when $\ce{NO}$ is passed through ferrous sulfate solution? If it is a brown ring complex then why does the complex sphere break upon ...
6
votes
1answer
4k views

Why is tetrathiocyanatocobaltate(II) blue?

Why is $\ce{Co(SCN)_{4}^{2-}}$ blue? I simply can't predict the colors of such inorganic salts. I have learned that $\ce {Co^{2+}}$ salts are pink in color. Also, if the ligand is a strong field ...
5
votes
1answer
2k views

The Acidity of the Hydrated Iron (III) Ion

Why is $\ce{Fe(OH_2)_6^{3+}}$ fairly acidic? This iron has six water molecules coordinated to it. In other words, water itself is a very weak acid. But when water is coordinated to iron, it becomes ...
15
votes
1answer
4k views

The bond in coordination complexes

This is a very basic question and I'm surprised it only just struck me. The nature of the bond in coordination complexes is a coordinate covalent bond. Only the ligand donates electrons for bond ...
2
votes
3answers
363 views

Heating CrCl3(bpy)3 — isomerism and ligand exchange

$\ce{CrCl3(bpy)3}$ (A) when heated forms (B) which has the formula $\ce{CrCl3(bpy)2}$ and has one free $\ce{Cl-}$ per mole of (B). B can react with ethylene diamine ($\ce{en}$) to form (C) which has ...
1
vote
1answer
3k views

How can the 18 electron rule be used to explain that Fe(η5-C5H5)2 doesn't react with hydrogen but Ni(η5-C5H5)2 does?

Fe(η5-C5H5)2 does not react with hydrogen, but its nickel analogue, Ni(η5-C5H5)2 is readily hydrogenated to give Ni(η5-C5H5)(η3-C5H7). Use the 18 electron rule to explain this behaviour. My answer so ...
0
votes
1answer
456 views

Zinc Picolinate - Positive, negative or neutral charge?

I'm going to be using a finings agent with a positive charge to remove negative trub from a solution (beer). I would like to keep some chelated zinc in the solution - ideally zinc picolinate - so ...
1
vote
1answer
850 views

Different coloured chromium salts

Evaporating cold aqueous chromium(III) chloride produces violet crystals. However when hot aqueous chromium(III) chloride crystallizes, green crystals result. Could someone please explain the ...
1
vote
2answers
14k views

What reaction takes place when potassium iodide is added to a tetraammine copper(II) complex?

I am given a blue solid W and it contains a tetraamine copper(II) complex and a $\ce{SO_4^{2-}}$. I added dilute sulfuric acid until the solution is pale blue; then added potassium iodide solution. A ...
5
votes
1answer
2k views

How is an aqueous Ag+ the same as [Ag(H2O)2]+?

$\ce{Ag^{+}_{(aq)}}$ can be written as $\ce{[Ag(H2O)2]+}$ but how would you know that it bonds with 2 water molecules? I don't get when ligands randomly form 6, 4, 2 bonds.
1
vote
1answer
1k views

What are the products of [Ti(H2O)6]Cl3 + H2SO4 + K2Cr2O7 --->

I am slightly lost on how to proceed with this equation. I know potassium dichromate is a strong oxidizing agent but I am unsure of how to deal with it along with the titanium complex. I was wondering ...
4
votes
1answer
3k views

How does CrF₆³⁻ hybridize?

My textbook says that $\ce{[CrF6]^{3-}}$ is an example of $sp^3d^2$ hybridization. But I don't really see how. Chromium has an electronic configuration of: $$3d: \boxed{\uparrow}\boxed{\uparrow}\...
2
votes
2answers
6k views

Predicting bond-strength of metal carbonyls

The metal carbonyls (and similar organometallic compounds) involve a combination of sigma bond, a pi bond and backbonding. The bond strengths under consideration are the metal-carbon bond and the ...
1
vote
1answer
891 views

Ligand exchange reactions… are they one way or reversible?

Are ligand exchange reactions one-way reactions or reversible? I know this is a very silly question but its not said outright in any place... For example, in my high school chemistry book, these two ...
15
votes
2answers
3k views

What happens to electrons in metal complexes after excitation by visible light?

My book writes: When white light shines through a solution of a complex ion of a transition metal, photons of a particular frequency are absorbed and their energy promotes an electron from lower ...
15
votes
1answer
5k views

Splitting of $d$ orbitals when ligands approach central metal ion

In my high school chemistry book, it is written that when ligands approach the central metal ion (transition metal ion) to form dative bonds, the $3d$ orbitals split into two: two which are in higher ...
4
votes
1answer
3k views

How can different no. of unpaired electrons lead to different colours of co-ordination compounds?

To make the question clear I would like to take an example. $\ce{K_3[Fe(CN)6]}$ and $\ce{K3[FeF6]}$ shows different colors in solutions. It is given in my textbook that it is because of different ...
0
votes
1answer
80 views

Does deprotonation of a hexaaquaion continue until neutral charge

I learned that deprotonation is the process in which a proton is lost from ligand $\ce{H2O}$ molecules surrounding a central metal ion (I am referring to hexaaqua ions). Also, the process continues ...
3
votes
2answers
33k views

Werner's theory and complex salts

According to Werner's theory, metal ions have two types of valency-primary and secondary, where the primary valency is said to be satisfied by negative ions only, and the secondary valency can be ...
1
vote
1answer
81 views

Does chelation take ions out of solution

Does EDTA take $\ce{Mg^{2+}}$ and $\ce{Mn^{2+}}$ out of solution, so that it can be removed by a filter? Or does it just take it out of any chemical reactions going on in the solution?
16
votes
3answers
21k views

Hybridisation of Mn in potassium permanganate

I'm clear with the concepts of crystal field theory. But I can't figure out the exact reason why the hybridisation of manganese in potassium permanganate ($\ce{KMnO4}$) is $\mathrm{d^3s}$. Can anyone ...
1
vote
1answer
746 views

Which d-orbitals split according to CFT?

According to CFT, the degenerate d-orbitals split into $eg$ and $t_2 g$ groups. Are these the outermost nd orbitals which are vacant(4-d in case of 4th period) or the penultimate filled (n-1)d ...