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Chemistry Forums for Students => Inorganic Chemistry Forum => Topic started by: ethylenediamine on November 01, 2006, 04:27:25 PM

Title: Inorganic Chemistry
Post by: ethylenediamine on November 01, 2006, 04:27:25 PM

1) Construct two MO diagrams for C2: one with sp mixing and one without.
the following for each MO diagram:
a. What is the bond order?
b. Is the molecule paramagnetic or diamagnetic?
c. Would you expect to observe sp mixing? Please explain.

How should I start this??? Any help will be appreciated.

Title: Re: Inorganic Chemistry
Post by: Dan on November 01, 2006, 05:29:50 PM

How far have you got? Do you have the MO diagram?

Title: Re: Inorganic Chemistry
Post by: DevaDevil on November 03, 2006, 07:45:40 PM

First of all you start with taking a single carbon atom.

Make the MO first without sp-hybridisation: (1s) 2s orbital, 3 2p
Fill in with electrons; 6 of them
Then you put 2 of them next to each other and make the C₂ diagram, with bond coupling.
Fill in with the total of 2 x 6 (12) electrons, from the bottom.
Look at the filled orbitals: (Bonding - Antibonding) gives the bond order.
Are all the electrons coupled? Yes: Diamagnetic, No: Paramagnetic

Then with sp-hybridisation:
Make the single MO again: (1s) 3 sp² and 1p_z
Put 2 of them next to each other again, and fill in the electrons.
Bond order is again (Bonding-Antibonding), and magnetism is the same definition as well.

Which one has the highest bond order? So which one will you expect to see?



Spoiler for the non-sp-hybridised Carbon (1s orbital not displayed):
Here (http://www.chem.queensu.ca/people/faculty/mombourquette/FirstYrChem/Molecular/orbitals/carbon.gif)