Jan 29, 2022 16:41
This idea of looking at orbitals as functions is what gives rise to the molecular orbital theory. Take your trisilylamine (for example). The silicon is bonded using sp3 hybrid orbitals (taking the liberty mentioned above :) to hydrogens who are using their 1s orbitals. Again, f(sp3) is a function, g(1s) is a function. It means that we can write a function k(f(sp3) + g(1s)) that will minimize energy for some k belonging to R. Now, what is this sudden maths I threw here?!
Do you know what this function is? This function represents the Si-H sigma bond! :) The simple visualization you make when you make an "orbital diagram" of a kinda lobe-shaped sp3 hybrid orbital "overlapping" with a spherical 1s hydrogen orbital, you were actually making a visual representation of this very linear combination of atomic orbitals (LCAO). (Heard this name? Nothing more than this algebraic addition of functions :)
But wait, I could have also combined these as f(sp3) - g(1s) right? (Forget the coefficient for now). Seems like a valid additive operation with just the sign changed. Hmm, great. Let me call this function "sigma*" for now (you will see why).
Now, there are popular science ideas right, like every particle has an "anti-particle" right. Combine two of them and they nullify sthg like that :)
Although this is not related, this isexactly what you mean by two quantities bein "anti". Getting back to our functions, if f(sp3) + g(1s) was our like our "particle", f(sp3) - g(1s) is kinda like our "anti-particle" right? (just an analogy, don't challenge me here :)
Whatever effect adding those two functions had, adding the minus sign guy just nullified that! It's like only the effect of one function remains, just "amplified" a bit by a factor of 2 (2f(sp3)). Hence this minus guy has a special name- if addition if the "bonding" orbital function, this is the "anti-bonding" orbital function :)
Now, visualization: If the bonding molecular orbital could be seen as overlap of constituent atomic orbitals between the N and Si centers, where should the antibonding guy be located? If it is indeed "anti", this particular combination should lie outside the N and Si along the same line!
This is precisely how you see the sigma* Si-H. Now, since the sigma bond can rotate freely, the "anti-sigma" bond should also be able to rotate freely (logical). Adjacently you have N with lone pairs in a parallel p-orbital. Clearly you can have aligenments where the sigma* Si-H orbital can overlap with the lone pairs of N. As soon as it accepts electrons: boom! The sigma bond had two electrons, anti sigma bond has two electrons, so they nullify. Si-H bond breaks and a new Si=N forms
This is exactly what's described in that answer :-). Such overlaps can generally take place anywhere when the anti-guy can overlap with an electron source, it cancels out with it's counterpart, and hence a conjugation sets up which brings nearbout planarity for max overlap
Also, I posed a question longtime ago but got caught up in sthg so couldn't reply, sorry for that. Am posting the solution for that and also a few of my answers on inorganic reactions that should help you develop an intuition for things :)
^This is the solution for the question I posed on Dec 21(Scroll till the end under the EDIT section)
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I will be using an approach which has been enlisted in the following book for answering this question: Arrow Pushing in Inorganic Chemistry ;A Logical Approach to the Chemistry of the Main-Group Elements
To start off, please go through my answer to this question: Why is chromate stable in basic m...
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I will be using an approach which has been enlisted in the following book for answering this question: Arrow Pushing in Inorganic Chemistry ;A Logical Approach to the Chemistry of the Main-Group Elements
The preface of the book says:
The approach: These reactions represent important facets of th...
Go through these answers and don't worry about the comments. The important idea is to get your motors running on highly probable ways these things can happen.
@AshishAhuja I also answered one of your questions similarly in the comments. Check the following and try to see if it makes sense :)
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I came across a question in which the following reaction was taking place:
$$
\ce{Mg4C3 + H2O -> CH3CH \bond{#} CH}
$$
Each $\ce{Mg}$ atom must be present in a +2 oxidation state, thus the total charge of the cation is +8. We thus have a $\ce{C3^{8-}}$ anion. The only structure of this $\ce{C3^{8...
Hope all of this helps :)
I want to know the hybridization of the central atom in $\ce{(SiH3)3N}$.
I think it should be $\mathrm{sp^3}$, because $\ce{N}$ is attached to three silicon atoms and one lone pair. But actually it is supposedly $\mathrm{sp^2}$.
How is this so?
