I studied molecular orbital bonding theory (basically quantum mechanics as applied to atoms, spread out to molecules) quite a bit. You could'nt possibly do any higher organic chemistry without it since it explains all the oddities that occur rather nicely. Try explaining boron hyrdides such as B2H6 without it and you go mad
I fell in love with MO as soon as I learned about it in the 1st year... I could never get my head around Valence Shell Electon Pair Relpulsion Theory, it never made any sense... But an MO diagram makes perfect sense! I refused to use VSEPR after that, and actaully lost marks in my coursework simply because I used MO when I should have used VSEPR.
Apparently VSEPR is really good for on-the-fly/rule-of-thumb stuff... my arse (TPG)... MO or nothing I said... my stubboness has cost me a lot :-(
-Edit- To this day I still tell any GCSE/A-Level Chemists that VSEPR is a lot of wank... and explain to them MO instead.
