View source for Talk:Mod 1: Tom Campling

1.2.1 Cp dimers:  Energies and structures are fine.  What is the basis of the endo rule?  What are the structural features causing the difference in bending strain between 3 and 4?

1.2.2 NAD:  It’s not quite that MM2 can’t recognise just metals.  A better way to display your minimisation would be in a graph of total energy vs dihedral angle.  Your answers are correct but a little brief.

1.2.3 Taxol:  Your energies are correct but where is your analysis?  You need to take me through the work you’ve been doing, show your working.

1.3.1 Carbene:  Good to see you’ve picked up on the bug in PM6 and found a way around it.  Much better analysis here.

Mini-project:  What reaction made these isomers?  NMR spectra, not readings.  If you’re going to number the atoms in a table, I’m going to have to know which ones are which on the molecule.  Nice to see you’re graphically comparing your calculated and experimental shifts but a better property to compare would be the difference alone (say, in a bar chart).  So can 13C NMR be applied to distinguish between these isomers?  What about any other analytical thechniques?  

Overall:  Your answers were rather brief and, at times, didn’t really explore the problems at hand.  But your structures and energies were all spot on so you obviously understood what you were doing.  A strong piece of work.