Ethylene

• Standard bonding picture for
ethylene is viewed as being made
from 2 sp2 hybridized C atoms, and
consists of a C-C double bond.
• MOT does not employ hybridization
and does not assume bonding
arrangements.
• Build ethylene from two CH2 groups
without preconceived bonding
arrangements.

• As with ethane earlier, the MO’s
derived from σ(CH2) and π(CH2)
make four MO’s that are primarily C-H
bonding - do not change much with
mixing in forming C-C bond.
• [σ(out)+ σ(out)] is the major σ bond
component, while (p+p) mixing
produces the π bond.
• Each CH2 group brings 6 valence ē
(total of 12 ē).
• The π orbital is the HOMO, and the
LUMO is the out-of-phase combination
of the p orbitals (which is antibonding).