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Molecular Orbital Theory

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Original post by illusionz
It's even better at cambridge! This year I've only done organic/biological and a little bit of main group organnometallics. No physical or theoretical :biggrin: Only had to do a little bit of huckel theory and high resolution spectroscopy last year too. No thermodynamics since 2nd year!


You don't know how much I hate you for that :P
Original post by JMaydom
You don't know how much I hate you for that :P


Given the hours of my life I've lost to a synthetic lab... I'm think it's only fair I don't struggle with maths any more :tongue:
Original post by illusionz
Given the hours of my life I've lost to a synthetic lab... I'm think it's only fair I don't struggle with maths any more :tongue:


I'm spending my whole time next year in the labs, 9am-6pm every day.
Original post by JMaydom
I'm spending my whole time next year in the labs, 9am-6pm every day.


What sort of lab? I presume from how long you'll be spending that it's synthesis of some sort? I reckon I was in the department from 9-6 every day this year too, but we had a lecture or two most mornings as well.
Reply 24
Original post by illusionz
What sort of lab? I presume from how long you'll be spending that it's synthesis of some sort? I reckon I was in the department from 9-6 every day this year too, but we had a lecture or two most mornings as well.


cambridge part III seems to have written paper components as well. our part II is entirely lab-based with a thesis + viva at the end. my last written papers were finals at end of third year.:biggrin:
Can't wait for my chemistry degree :mmm:

MO = Molecular Orbit?
AO = Atomic Orbit?

So what happens when atoms fuse?:eek:

What's this Bonding, Non-Bonding and Anti-Bonding jazz?!:biggrin:
Original post by L'Evil Fish
Can't wait for my chemistry degree :mmm:

MO = Molecular Orbit?
AO = Atomic Orbit?

So what happens when atoms fuse?:eek:

What's this Bonding, Non-Bonding and Anti-Bonding jazz?!:biggrin:


AO = Atomic Orbital
MO = Molecular Orbital

It's a bit much for me to explain, google 'introduction to molecular orbitals' and see if you can understand it.
Original post by illusionz
AO = Atomic Orbital
MO = Molecular Orbital

It's a bit much for me to explain, google 'introduction to molecular orbitals' and see if you can understand it.


Aah, thanks! If I have questions, do you mind if I ask you them?
Original post by shengoc
cambridge part III seems to have written paper components as well. our part II is entirely lab-based with a thesis + viva at the end. my last written papers were finals at end of third year.:biggrin:


Gah wish i didn't have exams this year. At least I have the BA to fall back on if it all goes tits up. Haven't even started revision yet because of the thesis to write up!
Original post by L'Evil Fish
Aah, thanks! If I have questions, do you mind if I ask you them?


Nah that's fine. I'm secretly desperate for something to do which isn't analysing complicated nmr spectra for my project!
Original post by illusionz
Nah that's fine. I'm secretly desperate for something to do which isn't analysing complicated nmr spectra for my project!


Don't worry, looking at it, I'll probably have many questions! And I wouldn't even know how to ask the questions :tongue:

Good luck with your project
Reply 31
Original post by illusionz
Nah that's fine. I'm secretly desperate for something to do which isn't analysing complicated nmr spectra for my project!


you doing organic? i did have quite complicated NMRs due to major/minor isomers as well and many aromatic groups. haha, but hey, all the HSQC/HMBC (or analogues) does help, right? should have characterised your stuff as you make them....:wink:
Original post by shengoc
you doing organic? i did have quite complicated NMRs due to major/minor isomers as well and many aromatic groups. haha, but hey, all the HSQC/HMBC (or analogues) does help, right? should have characterised your stuff as you make them....:wink:


It's basically organic, using a chiral nickel complex to make α,α-disubstituted Amino Acids. But I have loads of complexes similar to the one attached, and they're not the easiest thing to analyse!!

And yeah, I analysed diagnostic peaks as I made stuff, but the NMR are so complicated I couldn't be bothered to do the full thing. I know how to analyse cosy, but never actually learnt about HMQC so not entirely sure what's going on in them :tongue:

Reply 33
Original post by illusionz
It's basically organic, using a chiral nickel complex to make α,α-disubstituted Amino Acids. But I have loads of complexes similar to the one attached, and they're not the easiest thing to analyse!!

And yeah, I analysed diagnostic peaks as I made stuff, but the NMR are so complicated I couldn't be bothered to do the full thing. I know how to analyse cosy, but never actually learnt about HMQC so not entirely sure what's going on in them :tongue:



analyse your parent organic compound/ligand first, then your simplest complex, then correlate peaks in similar regions with analogous complexes - you know all this, of course

also, get your post-doc/phd supervisor who might have the time to spare, to help guide you through characterising at least one of your spectra

once you get the idea, the others are pretty self-explanatory.

i had about 10 of titanium-aromatic-complexes and couple of organic products to characterise last year too. i gave up on the aromatics eventually though....too many and too worthless in my opinion - like who is going to care about this work?:biggrin:
Reply 34
btw, hmqc is simple; the carbon correlating to the proton tells you that, that hydrogen belongs to that carbon. of course, those that dont have protons wont correlate with the proton spectra

hmbc shows you coupling between protons and the carbon two positions away. i.e. ortho proton would be coupled to an ipso carbon in its hmbc.
Original post by shengoc
analyse your parent organic compound/ligand first, then your simplest complex, then correlate peaks in similar regions with analogous complexes - you know all this, of course

also, get your post-doc/phd supervisor who might have the time to spare, to help guide you through characterising at least one of your spectra

once you get the idea, the others are pretty self-explanatory.

i had about 10 of titanium-aromatic-complexes and couple of organic products to characterise last year too. i gave up on the aromatics eventually though....too many and too worthless in my opinion - like who is going to care about this work?:biggrin:


Exactly. I'm pretty much just checking the integration checks out with what I would expect and then calling half of the peaks multiplets. Cheating a bit I know, but as I've been told we don't even include the spectra in Part III write ups, all I'll be doing is listing the peaks, and it's not like the marker is actually going to care.

I've also got the added complication that my supervisor left the group just before the easter vacation, and no-one else has a clue about what I did for my project. Kinda annoying.
Reply 36
Original post by illusionz
Exactly. I'm pretty much just checking the integration checks out with what I would expect and then calling half of the peaks multiplets. Cheating a bit I know, but as I've been told we don't even include the spectra in Part III write ups, all I'll be doing is listing the peaks, and it's not like the marker is actually going to care.

I've also got the added complication that my supervisor left the group just before the easter vacation, and no-one else has a clue about what I did for my project. Kinda annoying.


Geez, that sucks. i know how big a difference having a good day-to-day supervisor around as a mentor can be. I am eternally grateful to mine, at least.:biggrin:

trust me, if you have the crystal structure of at least one of those organometallic species, to hell with the rest of the spectra. what better proof is there, right?
Original post by shengoc
Geez, that sucks. i know how big a difference having a good day-to-day supervisor around as a mentor can be. I am eternally grateful to mine, at least.:biggrin:

trust me, if you have the crystal structure of at least one of those organometallic species, to hell with the rest of the spectra. what better proof is there, right?


None of them would crystallise nicely :frown: Whenever I removed solvent in vacuo, they would just form a glass-like compound stuck to the walls of the RBF. Sometimes under hi-vac I'd get that fluffy-flaky stuff, but never crystals.
Reply 38
Original post by illusionz
None of them would crystallise nicely :frown: Whenever I removed solvent in vacuo, they would just form a glass-like compound stuck to the walls of the RBF. Sometimes under hi-vac I'd get that fluffy-flaky stuff, but never crystals.


ermm, you didn't work in an organometallic group, did you? how i usually got my crystal is basically you never remove all the solvent - you simply saturate your mother liquor and let it be in cool surrounding, at RT, then fridge (5 degree C) then freezer (-30 C) then even colder gradually to see if single crystals form

i think perhaps there isnt a crystallographer in your group, otherwise you'd all be aware of this. on my luckiest day, i have got three schlenks with single crystals once.
Original post by shengoc
ermm, you didn't work in an organometallic group, did you? how i usually got my crystal is basically you never remove all the solvent - you simply saturate your mother liquor and let it be in cool surrounding, at RT, then fridge (5 degree C) then freezer (-30 C) then even colder gradually to see if single crystals form

i think perhaps there isnt a crystallographer in your group, otherwise you'd all be aware of this. on my luckiest day, i have got three schlenks with single crystals once.


Nope, it was a biological group. We didn't attempt to grow a crystal because my supervisor didn't think an X-ray structure was necessary, but when I just left stuff in a vial to evaporate, crystals didn't form, they just became very glass like.

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