IR spectra and point group symmetry

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The discussion centers on the reaction of anisole with hexacarbonylchromium, resulting in the formation of a complex where two carbonyl ligands are replaced by anisole, creating a 2-η ligand with chromium. The participant notes the impact of point group symmetry on the IR spectra of the resulting Cr(CO)4(anisole) compound. They observe a distinct peak at 1830 cm-1 for the CO stretch and a lesser peak at 1930 cm-1, hypothesizing it relates to electron backbonding to the carbonyl ligands. The inquiry seeks clarification on how symmetry influences the IR spectra and suggests comparing it to the spectrum of pure Cr(CO)6 for further insights.
Bladibla
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Hello

I'm currently studying the reaction of anisole with hexacarbonylchromium, and experiment shows the displacement of 2 of the carbonyl ligands with the anisole group, forming a 2-η ligand with the chromium ion.

After refluxing to obtain the crystals, IR and nmr spectra of the sample were obtained; Apprarently, the point group symmetry of the complex affects the IR spectra of the Cr(CO)4(anisole) compound, but I cannot see how it would affect the IR. Currently, In my IR spectra, I have a distinct peak at 1830 cm-1 corresponding the the CO stretch, and a lesser but nevetheless signficant peak at 1930 cm-1, which I can currently hypothesise is due to the backbonding of electrons to the carbonyl ligands.

Can anyone help with this?

Thanks.
 
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I doubt anyone can say offhand. But yeah, probably the C-Cr stretch. Have you compard to the spectrum of pure Cr(CO)6?
 
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