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Chemistry Forums for Students => Inorganic Chemistry Forum => Topic started by: xshadow on June 30, 2021, 07:42:05 PM

Title: Mo(CO)6 and Mo(CO)5PPh3 :CO vibrational stretching
Post by: xshadow on June 30, 2021, 07:42:05 PM

How does the CO-vibrational frequency  change when I pass from  Mo(CO)₆ to Mo(CO)₅PPh₃??

PPh3 is a strong sigma donor...so the metal has more electron density and  I think the retrodonation on the CO will be greater --> so I think the frequency will decrease.

Can have it sense??
Thanks

Title: Re: Mo(CO)6 and Mo(CO)5PPh3 :CO vibrational stretching
Post by: Orcio_87 on July 01, 2021, 09:24:42 AM

True, substition of CO with PPh₃ lowers frequency of remaining C=O about 54 cm^-1.