Is Berrylium Capable of Showing an Oxidation State of +6?

[mooncrater]

Homework Statement

While studying alkaline Earth metals of the s block elements I found this equation :
Be (OH)₂+2HCl +2H₂O →[Be (OH)₄]Cl₂

It is clear that in the complex, the oxidation state of Berrylium is +6. But how is even that possible?

Homework Equations

None

The Attempt at a Solution

We know that Be has only 2 electrons in its s orbital and moreover has a total of only 4 electrons, so how is even that possible?

 

[Borek]

Wouldn't hurt to check if the equation is balanced. If it is not, it is wrong.

 

[Raghav Gupta]

Well it's an amazing question.
Don't know about you but find that reaction in my NCERT book.
The only reason I can guess is OH donating its electrons to empty p orbitals of Berylium and therefore Berylium having that additional six electrons.
It is related to ligand theory.

 

[Raghav Gupta]

Wouldn't hurt to check if the equation is balanced. If it is not, it is wrong.

Yeah it is not balanced. Don't know why in my book it is given as same as the mooncrater's equation.
Can you, mooncrater give the reference of taking the reaction?

 

[Borek]

Mistake is quite obvious here.

Hint: water is a good ligand.

 

[Raghav Gupta]

Mistake is quite obvious here.

Hint: water is a good ligand.

Is that intended for me? Well I am not a expert in ligand theory. This thread brought an interest in me and I wanted to be in discussion.
So then my reason is incorrect for OH donating electrons to empty p orbitals of Berylium?

 

[Borek]

You don't have to be an expert to understand that the reaction that is not balanced is wrong. Beryllium compound - as written - doesn't exist. And I gave you both a hint to what does the real compound look like.

 

[Raghav Gupta]

Yeah, the equation should be,
$Be(OH)_2 + 2HCl + H_2O → [Be(H_2O)_3] Cl_2$
Thanks Borek Sir.
The question remains for mooncrater that how in book that he is reading, wrong equation is written?

As in my book also same equation is given and our teacher ask to rote memorise it without proper logic.

Though I have passed my 11th grade, I never realized it.
Once again thanks Borek Sir

 

[Borek]

Why Be(H₂O)₃²⁺?

 

[Raghav Gupta]

Why Be(H₂O)₃²⁺?

Because H₂O has a zero charge and Berylium would get +2 charge, which is its normal state.

 

[Borek]

But why 3 water molecules? Why not 2 or 4?

 

[Raghav Gupta]

For balancing purpose. Otherwise reaction would not be balanced.
Like the way, you are making sure that I get every concept of this question.

 

[mooncrater]

It is from NCERT 11TH

 

[Raghav Gupta]

As I was suspecting.

 

[Borek]

For balancing purpose. Otherwise reaction would not be balanced.

Be(OH)₂ + 2HCl + 75H₂O → [Be(H₂O)₇₇]Cl₂

Balanced?

Google for beryllium aqua complex.

 

[mooncrater]

Main reason for not balancing it:
It is in our course book.
Now it's purely impossible for the complex to exist.
According to me [Be (H₂O)₃]Cl₂(as Raghav said)
should exist as Be has 2 electrons in its outermost orbital and needs 6 more for inert gas configuration. For that 3 H₂Ogroups are needed.
Is it correct?

 

[Raghav Gupta]

Be(OH)₂ + 2HCl + 75H₂O → [Be(H₂O)₇₇]Cl₂

Balanced?

Google for beryllium aqua complex.

Searched it and got that Be is more stable when 4 molecules of H₂O are bonded to it as Ligands.
Reaction should be
Be(OH)₂ + 2HCl + 2H₂O → [Be(H₂O)₄]Cl₂

mooncrater I realized that I was wrong.
The compound should be [Be(H₂O)₄]Cl₂.
The reason is that , the coordination entity is having Be²⁺ not simply Be
So 2s orbital , 2py,2px, 2pz orbitals are empty which hybridise to accommodate lone pairs of 4 water Ligands.

 

[mooncrater]

Okay I got it now. Thanks.