credit: The OrbitronUniv. of Sheffield

Basis Set Description

Number of Functions

Rel. Energy (kcal/mol)

STO-3G 26 1577.0

3-21G 48 728.7

6-31G 48 108.9

6-31G* 72 54.7

6-311G* 90 28.8

6-311+G* 106 26.2

6-311++G** 130 20.4

6-311++G(2df,2pd) 226 11.4

6-311++G(3df,3pd) 264 10.1

cc-pVTZ 204 9.3

cc-pVQZ 400 0.7

aug-cc-pCVQZ 712 0.0

CGTO basis PNAO basis

1s and 2soverlap

1s and 2sorthogonal

2s PNAOon C

2s NAOon C

1s PNAOon H

H

H

1s PNAOon H

C

C

3.000.78 2 2 0.62 1CH C C Hs p s

NHO basis NBO basis

Cl

CC

D

0 20 40 60 80 100 120 140 160 180

0

1

2

3

4

5

6

to

C=

O

* in

tera

ctio

n e

ne

rgy (

kca

l/m

ol)

C-C-C=O dihedral angle

Angular Dependence of Hyperconjugation (D=CH3)

C

C

A

C

2.0 2.5 3.0 3.5 4.0

1

2

3

4

5

6

SiH3

BH2 H

SH Br

Cl

NH2

OH

F

C(sp3-sp3)C(sp3-sp2)

C(sp3-sp)

C(sp2-sp2/phenyl)

C(sp2-sp2/vinyl)

Str

en

gth

of H

yp

erc

on

jug

atio

n (

kca

l/m

ol)

Pauling Electronegativity

PH2

C-F is apoor donorincreasing s-character,

decreasing donor ability

Comparison of -Donor Ability

2.0 2.5 3.0 3.5 4.0

2

3

4

SiH3

BH2

H

PH2

SH

BrCl

NH2OH

F

CH3

Str

en

gth

of H

yp

erc

on

jug

atio

n (

kca

l/m

ol)

Pauling Electronegativity

C-F is poorlypolarizable

C-B is apoor acceptor

C-Br is agood acceptor

Comparison of -Acceptor Ability

nO(p-type) to *C-Cl

25.3 kcal/mol

nO(p-type): 3% s, 97% p

nO(s-type) to *C-Cl

0.49 kcal/mol

nO(s-type): 36% s, 64% p

nO(p-type) to *C-Cl

0.00 kcal/mol

nO(p-type): 0% s, 100% p

nO(s-type) to *C-Cl

2.92 kcal/mol

nO(s-type): 42% s, 58% p

0 20 40 60 80 100 120 140 160 180

0

1

2

3

4

5

6

7

8

relative energy

total donation

into C-F * bonds

rela

tive

en

erg

y (

kca

l/m

ol)

F-C-C-F dihedral angle (degrees)

0 20 40 60 80 100 120 140 160 180

0

2

4

6

8

rela

tive

en

erg

y (

kca

l/m

ol)

H-S-S-H dihedral angle (degrees)

B3LYP/6-313g(d)

p-type lone pair:correct symmetry

(3.6 kcal/mol interaction)

s-type lone pair:incorrect symmetry

(no interaction)