As I begin my 19th year of teaching I realize that I do not have a good grasp of group theory or how to formally use it to determine the number of IR active vibrations in a species. I am trying to come up with a good exercise for my students that could introduce them to point groups and character tables.
In one of their early lab experiments, my students synthesize cis-MoO2(acac)2 and characterize it using IR and NMR (1H and 13C) spectroscopy. I would love to do an analysis of the Mo-O vibrations that would demonstrate that the cis isomer (C2 symmetry) would have two IR active Mo-O stretching vibrations (sym and asym) while the trans isomer (D2h symmetry) would have only one IR active Mo-O stretching vibration (asym). The problem is that I have gotten myself a bit muddled in my thinking and I need some help finding my way out. (Or if someone would want to help me develop an LO on this I would jump at the chance...)
Any thoughts or suggestions or offer of help would be greatly appreciated.