C C

g

u

u

g

g

u

C-C

C C

g

u

u

g

g

u

C-C

bonding

bonding

Two “O-H bonds”

anti-bonding

anti-bonding

non-bonding

non-bonding

Two “lone pairs”but not equivalent!

Mainly

F 2s lcao’s

Mainly

B 2s-F 2p lcao’s

Mainly

B 2p lcao’s

Note bonds!

F donor (sp) orbitals (6)S valence orbitals (9)

a1g

Oh

t1u

a1g

t1u

eg

3s

3p

a1g

t1u

eg

a1g

t1u

SF6

F.

FS

F F

F

F

F

z

y

x

2p

F.

Instead of;

3d t2g

eg

t2g

eg

Because harder to draw

a1g

Oh

t1u

a1g

t1u

eg

3s

3p

a1g

t1u

eg

a1g

t1u

SF6

F.

Bonding MO’s8 e- gives 4 bonds!

3d t2g

eg

t2g

eg

a1g

t1u

a1g

t1u

eg

3s

3p

a1g

t1u

eg

a1g

t1u

SF6

FS

F F

F

F

F

Two views:A) 4 bonds distributed over six S-F pairsB) 4 bonds (covalent ) + 2 “bonds” ionic (S6+-F-)

3s

Na

Cl (-13.7 eV)

Br (-12.5 eV)

I

F (-18.6 eV)F -

a1g

Oh

t1u

a1g

t1u

eg

4s

4p

ML6

L:

3d t2g

eg

6-donors ONLY,Like H or NH3

3rd row M,ValenceAtomic orbitals

Symmetry Adapted Group Orbitals for 6 -donors

a1g

Oh

t1u

a1g

t1u

eg

4s

4p

a1g

t1u

eg

a1g

t1u

ML6

L:

3d t2g

eg

t2g

eg

6-donors ONLY,Like H or NH3

3rd row M,ValenceAtomic orbitals

a1g

Oh

t1u

a1g

t1u

eg

4s

4p

a1g

t1u

eg

a1g

t1u

ML6

L:

3d t2g

eg

t2g

eg

6-donors ONLY,Like H or NH3

3rd row M,ValenceAtomic orbitals

M-L s bonding MO’s

M-L s anti-bonding MO’s

a1g

Oh

t1u

a1g

t1u

eg

4s

4p

a1g

t1u

eg

a1g

t1u

ML6

L:

3d t2g

eg

t2g

eg

6-donors ONLY,Like H or NH3

3rd row M,ValenceAtomic orbitals

M-L s bonding MO’s

M-L s anti-bonding MO’s

What is o?

Symmetry Adapted Group Orbitals for 6 -donors

a1g

Oh

t1u

a1g

t1u

eg

4s

4p

a1g

t1u

eg

a1g

t1u

L:

3d t2g

eg

t2g

eg

6-donorsLike Cl-

3rd row M,ValenceAtomic orbitals

M-L s bonding MO’s

M-L s anti-bonding MO’s

12 L orbitalst1ut1g

t2g t2u L

..

a1g

Oh

t1u

a1g

t1u

eg

4s

4p

a1g

t1u

eg

a1g

t1u

L:

3d t2g

eg

t2g

eg

6-donorsLike Cl-

3rd row M,ValenceAtomic orbitals

M-L s bonding MO’s

M-L s anti-bonding MO’s

12 L orbitals

t1ut1g

t2g t2u

t2g

Effect on o?

a1g

Oh

t1u

4s

4p

a1g

t1u

ML6

L:

3d t2g

eg

t2g

eg

3rd row M,ValenceAtomic orbitals

M-L s bonding MO’s

M-L s anti-bonding MO’s

12 L orbitals

t1ut1g

t2g t2u

6-acceptorsLike CO, CN-

12 L orbitalst1ut1g

t2g t2u

t2g

a1g

t1u

eg

a1g

t1u

eg

CO

3d

t2g

eg

t2g

12 L orbitals

t2g

t2g

eg

3d

t2g

eg

t2g

eg

o

3d

t2g

eg

t2g

eg

12 L orbitals

t2g

t2g

o

o

Case 1.L is innocent(sigma donor only)

Case 3.L is acid(sigma donor and acceptor)

Case 2.L is base(sigma donor and donor)

ML4 - D4h

M a.o.’s L a.o.’s

ML4 - D4h

M a.o.’s L a.o.’s

dz2

dx2-y2

dxy

dxzdyz

ML4 - D4h

M a.o.’s L a.o.’s