The number of carbonyl stretching modes observed in the IR spectra of ...
- For the metal carbonyl complex M(CO)5X, the point group is C4v.
- The symmetries of CO stretching modes for the C4v point group is A1, A1, B1, and E.
- Among these vibrational modes only A1, A1, and E are IR active.
- Thus for the complex M(CO)5X, the number of carbonyl stretching modes observed in the IR spectra is 3.
Hence, option 1 is correct.
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The number of carbonyl stretching modes observed in the IR spectra of ...
Understanding Carbonyl Stretching Modes in M(CO)5X
The number of carbonyl stretching modes in the IR spectra of the organometallic complex M(CO)5X can be determined based on its symmetry and molecular structure.
Complex Structure
- M(CO)5X is a transition metal complex where M is the metal, CO represents carbonyl ligands, and X is another ligand.
- The complex typically possesses a trigonal bipyramidal geometry due to the five CO ligands.
Carbonyl Ligands and Symmetry
- In a trigonal bipyramidal arrangement, the CO ligands can be categorized based on their positions: three equatorial and two axial.
- Given the symmetry of the complex, the CO stretching modes can be influenced by the distinct environments of these ligands.
Types of Stretching Modes
- Each CO ligand can undergo stretching vibrations, which are generally classified based on their orientations.
- Due to the symmetry and equivalent environments of the CO ligands, there are typically three distinct stretching modes observed in the IR spectra.
Conclusion
- Hence, the correct answer is that there are three carbonyl stretching modes observed in the IR spectra of M(CO)5X.
- This conclusion is based on the arrangement and symmetry of the carbonyl ligands within the complex, confirming that option 'A' is indeed correct.