Carbenes, Types Structure & Stability

1.Carbenes can react as both electrophile as well as nucleophile.

  1. Bond angles are 125-140° for triplet methylene and 102° for singlet methylene. Both are sp2 hybridised with bent Shape.

3.In Triplet carbene, One nonbonding unpaired electron is present in p orbital and other in sp2 orbital

  1. Singlet carbene is similar to carbocation.

  2. Triplet carbene is the more stable state and Singlet is the excited state species

6.Substituents that can donate electron pairs e.g., halogens, may stabilize the singlet state by delocalizing the pair into an empty p-orbital. No Corresponding stabilisation possible for triplet carbene due to unavailibility of vacant orbital at carbon.

  1. When there is a substituent with lone pairs, the singlet carbene is generally more stable than the triplet carbene. Dichlorocarbene is more stable in singlet.

Hence

Order of stability of singlet carbene: :CH2 > :CF2 > :CCl2 > :CBr2 > :CI2

& Order of Stability of Triplet Carbene: :CI2 > :CBr2 > :CCl2 > :CF2

 

Advertisements

2 thoughts on “Carbenes, Types Structure & Stability

Leave a Reply

Please log in using one of these methods to post your comment:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s