Question

IR absorption spectra of metal carbonyl determine: A. Geometry of mononuclear metal carbonyls, B. Determine bond order of CO bond, C. Differentiating between terminal and bridging CO, D. Enatiomerism in metal carbonyls, E. Study of Reaction Rates of Substitution reactions.

• A. A, B, C and D only
• B. A, B, C and E only
• C. B, C, D and E only
• D. A, C, D and E only

Hint:

IR is a "bonding detective," but it's blind to "mirror images" (Enantiomers).

Answer 1

The Correct Option is B

Step 1: Concept IR spectroscopy measures molecular vibrations, especially the CO stretching frequency ($\nu_{CO}$).

Step 2: Meaning $\nu_{CO}$ is sensitive to the bonding environment of the CO ligand.

Step 3: Analysis IR helps determine geometry via the number of bands (A). It reflects bond order through frequency shifts (B). Bridging CO has lower frequency than terminal CO (C). It can monitor reaction kinetics by tracking band changes (E). IR cannot determine enantiomerism (D) as enantiomers have identical IR spectra.

Step 4: Conclusion Features A, B, C, and E are applicable. Final Answer: (B)