Interesting References to read.

References relating to CO

1. Relationships in M-C and C-O distances, charge, ligands etc... A detailed database study 

2. Alternative ligands for CO!

3. Anamolous CO stretching frequency observed in a  gold complex.

4. An effort to understand the 5 sigma MO in Carbon Monoxide.
The problems in understanding changes in CO stretching  frequencies are discussed in this paper.

5.

Nobel lecture of Wilkinson  wilkinson-lecture.pdf

Nobel Lecture of  Roald Hoffman

allyl complexes and their complexities   allyl_syn_anti_p588.pdf