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### Topic: Si=O bond length  (Read 7881 times)

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#### lemonoman

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##### Si=O bond length
« on: October 21, 2005, 03:28:57 PM »
Okay, amateur question.

But for a lab report I'm writing, I need to know the bond length between silicon (Si) and oxygen (O).  And I absolutely can not find it, on the internet, it textbooks, anything.  Plenty (in fact almost ALL) include the bond length if it was a single bond...but none discuss the double bond length.

If anyone knows a textbook, journal, internet article, etc where I might find this value, it would be greatly appreciated!

#### Mitch

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##### Re:Si=O bond length
« Reply #1 on: October 21, 2005, 05:33:05 PM »
A quick MM2 calculation puts it at 1.512 A that should be good enough for most purposes.
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#### AWK

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##### Re:Si=O bond length
« Reply #2 on: October 26, 2005, 05:03:17 AM »
See in International Tables for Crystallography in your library.
Si-O vary within 1.53 A (for trydimite) to 1.81 (for stishovite).
Hence all shorter than 1.53 A can be Si=O
« Last Edit: October 26, 2005, 05:17:45 AM by AWK »
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#### DrCMS

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##### Re:Si=O bond length
« Reply #3 on: November 09, 2005, 02:53:17 PM »
What are you making that might have an Si=O?

#### lemonoman

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##### Re:Si=O bond length
« Reply #4 on: November 09, 2005, 03:23:47 PM »
I have already handed in my lab report for that class, but I will of course continue to answer/ask pertinent questions.

What I was doing was comparing the relative strengths of Si=O bonds against C=O bonds, with respect to an approximated overlap integral.  We used a formula to find S(r) where r is the bond length in Angstroms, and S is the value of the overlap (from 0 to 1).

The question was asked because we had just finished synthesizing a silicone polymer, from dichlorodimethylsilane.  I realize that this is a silane, not a ketone (or silicone, but the question asked referred specifically to a double-bonded oxygen.

So, in a nutshell, it was for comparison to Carbon.
« Last Edit: November 09, 2005, 03:24:11 PM by lemonoman »

#### Dude

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##### Re:Si=O bond length
« Reply #5 on: November 09, 2005, 05:26:32 PM »
If my memory serves me, there is no precedent for a silicon-oxygen double bond in typical molecules that are stable at room temperature.  I believe the word silicone is a misnomer based upon elemental composition studies that gave a composition of SiO(CH3)2 or something analogous to acetone (and hence the erroneous name).

#### AgG

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##### Re:Si=O bond length
« Reply #6 on: November 10, 2005, 07:59:21 PM »
I would look for anything done by Robert West.