Naked Science Forum

Non Life Sciences => Chemistry => Topic started by: StereoChemist on 26/04/2008 02:52:32

Title: Why is the sigma orbital higher in energy than the pi in carbon monoxide?
Post by: StereoChemist on 26/04/2008 02:52:32

my question is this, in carbon monoxide you have six p orbitals combining (3 from carbon 3 from oxygen) to form two pi molecular orbitals (px and py) and one sigma orbital (pz).  So why is the sigma orbital HIGHER in energy than the pi MO's generated.  The sigma orbitals overlap better I believe which would correspond to lower bonding MO created (i think better over lap means lower bonding and higher nonboding orbitals created)  Also we all know that pi electrons are usually more reactive, so wouldn't that mean they should br the higher energy ones, but they aren't they are lower. 

The only reason that makes sense that i can think of for this is that the sigma electrons are in a space of higher electron density (the plane of nuclei)  and would therefore have more energy.  It still doesn't sit right with me that pi electrons are more reactive and moving around more but they are lower energy than the sigma orbital. can somebody clear this up for me?

Title: Re: Why is the sigma orbital higher in energy than the pi in carbon monoxide?
Post by: StereoChemist on 01/05/2008 19:22:56

c'mon second question i've asked on this forum with zero answers.

Title: Re: Why is the sigma orbital higher in energy than the pi in carbon monoxide?
Post by: sorincosofret on 14/05/2008 12:30:32

Dear Stereo chemist,

Look a little bit at the folowing link http://www.elkadot.com/atomic/Coordinative_bound.htm and read on the coordinative bound link and you will discover another type of answer....for CO structure

Regards,

Sorin Cosofret


_{<mod edit - link changed directly to your hypothesis page so it's not just spamming your site>}

Title: Re: Why is the sigma orbital higher in energy than the pi in carbon monoxide?
Post by: BenV on 14/05/2008 12:54:30

Sorry StereoChemist, I've a zoology background so can't help with this one.  I'm sure someone will be able to help.

Title: Re: Why is the sigma orbital higher in energy than the pi in carbon monoxide?
Post by: StereoChemist on 29/05/2008 22:20:43

I get what that article is saying about CO but it still doesn't explain why the two similar orbitals (i called them pi orbitals in my original post) are lower in energy than the different orbital (i called it a sigma bond in my original post, the article refers to it as s coordinative bond).