The infrared spectra of trans - and cis - [Fe(CO)2(CN)4]2- and of [Fe(CO)(CN)5]3- are sh...

The infrared spectra of trans - and cis - [Fe(CO)₂(CN)₄]^2- and of [Fe(CO)(CN)₅]^3- are shown below.

a. Which stretching bands occur at lower energy, those for the CO ligand or those for the CN^- ligand? Explain.

b. How many C – O and C – N stretching bands would you predict for each of these complexes on the basis of their symmetry? Match the complexes with their spectra. (Reproduced with permission Inorg. Chem., 41, 1670. Copyright 2002. American Chemical Society.)