Questions tagged [transition-metals]

For questions about the characteristic physical properties, chemical reactions, etc. of d-block elements, group 3-12, or their compounds. Do not use this tag if your questions is about general properties of metals, use [metal] instead. Also see [rare-earth-elements].

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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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Hiyama vs Sonogashira coupling

Why is Sonogashira's coupling more feasible than Hiyama's coupling when both could occur? I have seen many examples in syntheses, here is one (the penultimate reaction):
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Changing iron(III) acetate to iron(II) acetate

Is there a way simple way to turn iron(III) acetate into iron(II) acetate or vice versa? Edit (as per answer below): an oxidiser like hydrogen peroxide will turn iron(II) acetate into iron(III) ...
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Mechanism for an Étard reaction (chromium complex)

In the following reaction, a chromium complex is formed during the Étard reaction: I have the following questions: How is this complex formed? How does its hydrolysis take place? (What's the ...
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What is the chemistry behind black colour of platinum black? [duplicate]

Platinum is a silvery white metal and is highly unreactive then why it's powdered form "platinum black" is platinum metal but is black in colour. why would a metal such as platinum become black as a ...
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What is the origin of the colour of azo dyes?

Is it the same reason as to why transition metal complexes have colour?
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How does aqua regia dissolve gold?

I recently learned that aqua regia can dissolve less reactive or noble metals like gold. Aqua regia is a mixture of $\ce{HCl}$ and $\ce{HNO3}$, but separately, neither of these acids dissolve gold. ...
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Why is Cr(2+) a stronger reducing agent than Fe(2+) in water?

According to me, $\ce{Fe^{2+}}$ should be a better reducing agent because $\ce{Fe^2+}$ - after being oxidized - will attain a stable $\ce{d^5}$ configuration, whereas $\ce{Cr^2+}$ will attain a $\ce{d^...
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Does a certain “Badecker reaction” actually exist?

A book I read, mentions a certain Badecker reaction under coordination chemistry. It goes like this: $$\ce{Na2[Fe (CN)5 NO] + Na2SO3 -> Na4[Fe (CN)5 (NOSO3)]}$$ I googled up the name, but I didn'...
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Cr(II) and Mn(III) - their oxidizing and reducing properties?

My textbook states that $\ce{Cr^2+}$ is a reducing agent while $\ce{Mn^3+}$ is an oxidizing agent in spite of both having $\ce{d^4}$ configuration. The explanation states that when $\ce{Cr^2+}$ gets ...
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How do I determine the crystal field splitting for an arbitrary point group?

How can I figure out the degeneracy of the d orbitals for a site that has a given point group? Specifically I'm interested in $D_{3d}$ and $D_{3h}$, but it would be good to know how to do it in the ...
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Why are compounds of V5+ and Cr6+ colored? [duplicate]

As far as my knowledge goes, transition metal complex ions show a color due to a transfer of electrons between the levels of split $\mathrm d$-orbitals. In the case of $\ce{V^5+}$ and $\ce{Cr^6+}$ ...
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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 ...
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Reference for electronegativities of different metal oxidation states

A long time ago I was researching the effect of the self regulatory response in Fe and Co. I found that my results made sense based on the idea of the electronegativity of the ions considered. I found ...
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Why do transition metals form particularly stable complexes?

The pre-transition metal ions can form complexes but the ligands are weakly bound unless they are multidentate and thus benefit from the chelate effect. For example, crown ethers and cryptands. ...
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Why doesn't the bidentate ligand form dative bonding three times?

I was looking at this question where it asked you to work out the final complex formed when an excess of 1,2-diaminoethane is added to and aqueous solution of copper (II) sulphate. So the equation I ...
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Does iron(III) sulfate react with copper?

As my understanding, there should be an oxidation-reduction reaction: $$ \ce{2 Fe^3+ + Cu → 2Fe^2+ + Cu^2+} $$ However, I always see the process using $\ce{FeCl3}$ to etch copper, but I never ...
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Why is ZnFe2O4 a normal spinel?

Considering that $\ce{Zn^2+}$ is $\mathrm{d}^{10}$, $\ce{Fe^3+}$ is $\mathrm{d^5}$, and $\ce{O^2-}$ is a weak field ligand, the CFSE values of both the normal and inverse spinel structures should be $...
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Different chemoselectivity of transition metals in catalytic hydrogenation

I am quoting my Clayden et al 2nd edition: Some catalysts are particularly selective towards certain classes of compound – for example, Pt, Rh and Ru will selectively hydrogenate aromatic ...
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Why does steric hindrance cause a d8 complex to have a tetrahedral geometry rather than a square planar geometry?

I'm currently working on a question based on two isomers of a nickel complex, where nickel exists in the oxidation state Ni(II) (i.e. has d-electron configuration d8). It has been deduced that the "...
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Why do iron(II) ions and chromium have different electronic configurations?

What I know: Empty 3d orbitals are higher in energy than empty 4s orbitals Aufbau Principle (electrons always go into an empty orbital with the lowest energy) Partially/half/fully filled 3d ...
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Brittle d-block metal trend

I remember seeing a periodic table that had the top-left corner of the d-block shaded and marked as "brittle". If I recall correctly, the elements were $\ce{Sc,Ti,V,Cr,Mn,Y,Zr,Nb,La}$. I think (sorry, ...
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How many electrons are in the d orbitals of NiCl2·6H2O?

On Wikipedia, it says that $\ce{NiCl2·6H2O}$ consists of separated trans-$\ce{[NiCl2(H2O)4]}$ molecules linked more weakly to adjacent water molecules. Only four of the six water molecules in ...
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Does tantalum and tungsten really not form amalgams?

User @Poutnik has recently answered two questions(here and here) in which he/she quoted this statement from Wikipedia: Almost all metals can form amalgams with mercury, the notable exceptions ...
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Only d orbital electrons for spin only magnetic moment

During my chemistry lessons and self studies, I have come upon many instances where I observed that during calculations of spin only magnetic moment of transition elements only the d orbital electrons ...
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Why does iron have an abnormally high ionization energy?

Along a period the ionization energy should increase because the atomic number is increasing, but there is negligible increase in shielding. However, $\mathrm{IE}_\ce{Mn} < \mathrm{IE}_\ce{Fe} > ...
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Why does the Co³⁺/Co²⁺ couple have such a high reduction potential?

Cobalt is changing from $\mathrm{(3d)^6}$ to $\mathrm{(3d)^7}$ electronic configuration. What's so stabilizing about that? Just by reduction potentials this couple is more oxidising than hydrogen ...
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Odd Acidity Trend in Hexaaqua Metal Complexes

In the following link (three quarters down the page) it states that theoretically there should be a proportional relationship between the ionic radius and pKa of a hexaaqua metal complex (provided ...
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Why is zinc more reactive than copper?

In terms of electronegativity, from what I understand electronegativity increases going across the period, so surely this should mean that zinc less readily loses its outer shell electrons than copper?...
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Strongest chloride complex as predicted by HSAB theory

Why won't $\ce{Ni^2+}$ form a complex with $\ce{Cl-}$, while the ions $\ce{Cu^2+}$ and $\ce{Co^2+}$ form the complexes $\ce{[CuCl4]^2-}$ and $\ce{[CoCl4]^2-}$? According to the HSAB theory, $\ce{Cl-...
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Why does Mn (II) behave as “hard”?

Why, within HSAB, does $\ce{Mn^{2+}}$ behave as a hard acid? If we go across the third block, then all metals to the left of manganese form soft divalent cations (e.g. $\ce{Ti^{2+}}$, $\ce{V^{2+}}$, $...
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Does copper(III) nitrate exist?

I was balancing this reaction when I found an unusual compound had been formed. $$\ce{Cu(s) + HNO3(aq)-> Cu^{3+}(aq) + NO(g)}$$ My attempt: Balancing oxidation number: $$\ce{Cu -> Cu^{3+} +3e^-...
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Color of Anhydrous Transition Metal Salt

Why are some anhydrous transition metal salts colored? Here are some examples I found. Anhydrous cobalt(II) chloride ($\ce{CoCl2}$), with sky-blue color. Anhydrous chromium(III) chloride ($\ce{CrCl3}...
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Why don't ligands affect the oxidation state of the central metal ion?

If $\ce{Fe^3+}$ were complexed with 6 $\ce{H2O}$ ligands, the resulting complex ion would be $\ce{[Fe(H2O)6]^3+}$, and the central metal ion would still have the same oxidation state of +3 as it did ...
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If the ferric ion is more stable than the ferrous ion, then why is it readily reduced to the latter?

The standard reduction potential value for the Ferric ion: \begin{align} \ce{Fe^3+ + e- &<=> Fe^2+} & E^\circ &= 0.77 \end{align} The value is positive, hence it means that ferric ...
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Why is enthalpy of atomization of Mn exceptionally low?

Transition elements usually have high values, especially so for greater number of unpaired electrons. Why the exception here?
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Symmetry and SALC: choosing coordinate basis

When we construct symmetry adapted linear combinations of orbitals (aka SOs) to build an MO diagram, we choose the z axis as the axis of highest symmetry and all other axis to make symmetry operations ...
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Dissociation rates: trans-effect rule in square planar complexes

In lecture, the trans-effect was described. A ligand $L^t$ with a higher trans-effect as $L$ (cis to $L^t$) leads to a faster dissociation of ligand $L^d$ (trans to $L^t$). I would expect that the ...
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Dehalogenation of vicinal dihalides

Why, among different metals, only zinc is favourable for the dehalogenation of vicinal dihalides?
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What wavelength of light is released when an electron drops an energy level in complexes?

I know that the color of transition metals is related to the splitting of the d-orbitals. Only a certain wavelength is absorbed in the promotion of electron to a higher d-orbital and therefore the ...
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Why are multiple oxidation states useful for a catalyst?

Transition elements are good catalysts because they have multiple oxidation states?Why multiple oxidation states matter?
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“Alternative” derivation of the spin-only formula

The spin-only formula $$\mu_\mathrm{so} = \mu_\mathrm{B} \sqrt{n(n+2)} = \mu_\mathrm{B}\cdot 2\sqrt{S(S+1)}$$ is usually a good first approximation to calculate the magnetic moment of transition ...
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Is iron(III) carbonate stable in water?

I searched for this onsite already, and also found the following answer on Quora: In aqueous environment, iron(III) is bound by water molecules and exists as $\ce{[Fe(H2O)6]^3+}$. Due to strong ...
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Why are the electronegativities of transition metals so similar to each other?

I was wondering why the electronegativity among transition metals are so similar. I can't find anything on the internet, just vague answers about the d orbitals that don't seem to provide a sufficient ...
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Trans effect on square planar complex [closed]

We've learnt about the trans effect but I have a question regarding how this plays a role with water in the equation. trans-effect: $$\ce{H2O < NH3 < Cl-}$$ Based on this, given cis-$\ce{[Pt(...
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Exceptions to the Madelung rule for electronic configurations

The electronic configuration of platinum is $$\mathrm{[Xe] 4f^{14} 5d^9 6s^1}$$ and not $\mathrm{[Xe] 4f^{14} 5d^{10} 6s^0}$ or $\mathrm{[Xe] 4f^{14} 5d^8 6s^2}$. I see this question has already ...
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Why is MnO2 not a peroxide?

As I know, $\ce{MnO2}$ is called manganese(IV) oxide. Why can't we name it manganese peroxide since manganese(II) exists too? In other words, how do we know that the oxidation number of manganese in ...
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Can one turn a nickel blue?

I've heard of artificial coin toning, but haven't been able to find a recipe for creating a blue (or blue-ish) nickel coin. While not a metallurgist, I work with one. She tried nitric acid, which ...
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What does the reaction of chromium with ozone form?

I know almost nothing beyond 10th grade chemistry. I'm trying to name a web application, and was wondering what the products are of a reaction between the element Chromium and the gas Ozone (...
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Is scandium considered a transition metal?

I have seen so many conflicting answers to this question in various places so I wanted to ask it again. IUPAC defines a transition element as an element whose atom has a partially filled d sub-...