Oxidative Additions: Don't Get How Metal Oxidizes?

  • Thread starter Thread starter CrimpJiggler
  • Start date Start date
Click For Summary

Discussion Overview

The discussion centers around the concept of oxidative additions in coordination chemistry, particularly how these processes affect the oxidation state of metals. Participants explore the definitions of oxidation and reduction, using examples such as methyl chloride and hydrogen chloride to illustrate their points. The conversation includes theoretical considerations and interpretations of chemical behavior.

Discussion Character

  • Exploratory
  • Debate/contested
  • Technical explanation

Main Points Raised

  • One participant questions how oxidative additions can be considered oxidation if the metal appears to gain electrons, suggesting this might be a reduction instead.
  • Another participant explains that in traditional definitions, oxidation involves the loss of electrons by the metal, using copper as an example.
  • A different participant proposes that in the case of oxidative addition with HCl, the oxidation state of the metal increases due to the nature of the bonding with chloride and hydrogen ions.
  • There is a discussion about the role of electronegativity in determining oxidation states and bond types, with one participant suggesting that carbon's ability to reduce metals is not solely based on electronegativity.

Areas of Agreement / Disagreement

Participants express differing views on the definitions and implications of oxidation and reduction in the context of oxidative additions. There is no consensus on how to interpret the changes in oxidation state or the role of electronegativity in these processes.

Contextual Notes

The discussion reflects varying interpretations of oxidation and reduction, and the assumptions underlying these definitions are not fully explored. The relationship between electronegativity and reactivity is also debated without a clear resolution.

CrimpJiggler
Messages
141
Reaction score
1
I don't get how oxidative additions "oxidize" the metal. For example, methyl chloride. Let's say the chloride anion donates 2 electrons to form a bond with the metal. The metal gains 2 new electrons so this is a reduction isn't it? The metals oxidation state should increase by 2. The methyl cation will also form a bond using two of the electrons from the metal atoms oxidation state should go down 2 again. I don't see how the metals oxidation state increases by 2.
 
Chemistry news on Phys.org
When oxygen reacts with something like a metal the oxygen atom gains two electrons and the metal loses two (e.g. Cu). Copper is oxidised as it loses electrons.

Reducesing is the opposite. The metal gaining electron would be reduction. Hense Carbon is know as a reducing agent for many metal oxides as the metal atoms gain electrons to form a metal solid.

That is how oxidation and reduction are defined.
 
Thanks, I learned a couple of things from your reply. It didn't answer my question though. I've figured out the answer to the question though. Using an oxidative addition of HCl as an example, the Cl- anion adds to the metal and since the Cl- donated both electrons, the oxidation state doesn't change. It didn't reduce the metal there though because Cl is far more electronegative than the metal and if the Cl leaves, its taking both electrons with it. The H+ counterion must now add to the metal and since it has no electrons, it takes 2 electrons from the metal to form the new bond. Hence, the oxidation state of the metal increases by 2.

What you said there got me thinking. You said carbon reduces the metal atom in metal oxides. The metal atom is less electronegative than carbon though. Therefore, is it only because carbon forms a stable gas with oxygen that this happens? In other words, the reaction would be in an equilibrium which favors the metal oxide but the product of the reaction between carbon and oxygen, since its a gas, leaves the reaction site as soon as its formed.
 
Last edited:
Electronegivity difference is a tool for telling you hove ionic or covelent a bond is. It also can be used to decide where the partial charge in a molecule resides if the bonds are polar. I would use it for more than that. Carbon reduces metals below itself in the reactivity series. I donlt think it has much to with electronegitivity.
 

Similar threads

Replies
3
Views
2K
  • · Replies 3 ·
Replies
3
Views
1K
Replies
6
Views
7K
  • · Replies 6 ·
Replies
6
Views
5K
  • · Replies 11 ·
Replies
11
Views
3K
  • · Replies 15 ·
Replies
15
Views
3K
  • · Replies 2 ·
Replies
2
Views
3K
  • · Replies 7 ·
Replies
7
Views
2K
Replies
3
Views
2K
  • · Replies 1 ·
Replies
1
Views
9K