In the substitution reaction below, the rate of reaction is overwhelmingly indep
ID: 1056832 • Letter: I
Question
In the substitution reaction below, the rate of reaction is overwhelmingly independent of the identity of PR3, where R is either methyl, ethyl, or butyl. Select the most likely reason for this.
Mo(CO)6 + PR3 Mo(CO)5R + CO R= methyl, ethyl or butyl
1. Methyl, Ethyl and butyl groups are all electron-donating
2. The reaction occurs via an associative mechanism
3. The reaction occurs via a dissociative mechanism
4. The additional steric bulk of tributylphosphine, which would make it slower to react, is offset by its stronger electron donating properties
Explanation / Answer
option 4 is correct
The additional steric bulk of tributylphosphine, which would make it slower to react, is offset by its stronger electron donating properties
the donating tendency increases because all the alkyl group are elctron donating
because of this electron density increases and PR3 act like nucleophile and easily replace CO which has less donating tendency