Page 31 - Mechanism and Theory in Organic Chemistry

and
Figure 1.9 The symmetry of the electron distributions I)$~~~~ I)~~,~,. Rotational
symmetry is C2.

orbitals of the p type can form either a or .rr orbitals, depending on their orienta-
tion relative td each other. Because the over& -- .- of p orbitals inter& -
_-_
manner is smaller than overiG in the a manneL ~he.A.kLhr~c~i~"in
MO
n
--
MO
f&Fation is usually less than in a -- -.-- formation.
--
1.3 HYBRID ORBITALS
Suppose that we wish to construct an LCAO bonding model for methane. We set
up the problem by defining an x, y, z coordinate system and placing the carbon at
the origin. The molecule is tetrahedral, as determined from the electron-pair
repulsion model. The orientation of the molecule is arbitrary; we choose to
arrange it as shown in 21, with the hydrogen atoms in the + x, +y, + z quadrant,
the - x, -y, + z quadrant, the +x, -y, - z quadrant, and the - x, +y, - z
quadrant.