PROPERTIES

OF ATOMS, RADICALS, AND BONDS

4.53

TABLE 4.11

Bond Dissociation Energies

(

Continued

)

Hf 298 ,

Hf 298 ,

Bond

kJ/mol

Bond

kJ/mol

Zirconium

Zirconium ( continued

)

Zr 9C

561(25)

Zr 9O

760(8)

Zr 9F

623(63)

Zr 9S

575(17)

Zr 9N

565(25)

Source:

T. L. Cottrell,

The Strengths

of

Chemical Bonds,

2d ed., Butterworth, London, 1958; B. deB. Darwent,

National

Standard Reference

Data

Series,

National

Bureau of Standards, no. 31, Washington, 1970; S. W. Benson,

J. Chem. Educ.

42: 502 (1965); and J. A. Kerr,

Chem. Rev.

66: 465 (1966).

All bonds between equal atoms are given zero

values. Because of their symmetry, methane and

ethane molecules are nonpolar. The principle of

bond moments thus requires that the CH

3 group

moment equal one H

9C moment. Hence the substitution

of any aliphatic H by CH

3 does not alter

the dipole moment, and all saturated hydrocarbons have zero moments

as long as the tetrahedral

angles are maintained.

TABLE 4.12

Bond Dipole Moments

Bond

Moment, D*

Bond

Moment, D*

H

9C

C

9N, aliphatic

0.45

Aliphatic

0.3

C

"N

1.4

Aromatic

0.0

C

#N (nitrile)

3.6

C

9C

0.0

NC (isonitrile)

3.0

C

#C

0.0

N

9H

1.31

C

9O

N

9O

0.3

Ether, aliphatic

0.74

N

"O

2.0

Alcohol, aliphatic

0.7

N (lone pair on

sp 3 N)

1.0

C

"O

C

9P, aliphatic

0.8

Aliphatic

2.4

P

9O

(0.3)

Aromatic

2.65

P

"O

2.7

O

9H

1.51

P

9S

0.5

C

9S

0.9

P

"S

2.9

C

"S

2.0

B

9C, aliphatic

0.7

S 9H

0.65

B

9O

0.25

S

9O

(0.2)

Se

9C

0.7

S

"O

Si

9C

1.2

Aliphatic

2.8

Si

9H

1.0

Aromatic

3.3

Si

9N

1.55

* To convert debye units D into coulomb-meters, multiply by

3.33564 10 30.

4.54

SECTION 4

TABLE 4.12 Bond Dipole Moments (

Continued

)

Bond

Moment, D*

Bond

Moment, D*

H

9Sb

0.08

Br

9F

1.3

H

9As

0.10

Cl

9F

0.88

H

9P

0.36

Li

9C

1.4

H

9I

0.38

K

9Cl

10.6

H

9Br

0.78

K

9F

7.3

H

9Cl

1.08

Cs

9Cl

10.5

H

9F

1.94

Cs

9F

7.9

C

9Te

0.6

N

9F

0.17

Dative (coordination) bonds

P

9I

0.3

P

9Br

0.36

N

: B

2.6

P

9Cl

0.81

O

: B

3.6

As

9I

0.78

S

: B

3.8

As

9Br

1.27

P

: B

4.4

As

9Cl

1.64

N

: O

4.3

As

9F

2.03

P

: O

2.9

Sb

9I

0.8

S

: O

3.0

Sb

9Br

1.9

As

: O

4.2

Sb

9Cl

2.6

Se

: O

3.1

S

9Cl

0.7

Te

: O

2.3

Cl

9O

0.7

P

: S

3.1

I 9Br

1.2

P

: Se

3.2

I 9Cl

1

Sb

: S

4.5

Br

9Cl

0.57

* To convert debye units D into coulomb-meters, multiply by

3.33564 10 30.

The group moment always includes the C

9X bond. When the group is attached to an aromatic

system, the moment contains the contributions through resonance of those polar structures postulated

as arising through charge shifts around the ring.

All values for bond and group dipole moments in Tables 4.12 and 4.13 were obtained in benzene

solutions.

TABLE 4.13

Group Dipole Moments

Moment, D*

Group

Aromatic C

9X

Aliphatic C

9X

C

9CH

3

0.37

0.0

C

9C 2H

5

0.37

0.0

C

9C(CH

3 )3

0.5

0.0

C

9CH

"CH 2

0.4

0.6

C 9C #CH

0.7

0.9

C

9F

1.47

1.79

PROPERTIES OF

ATOMS,

RADICALS,

AND BONDS

4.55

TABLE 4.13

Group Dipole Moments (

Continued

)

Moment, D*

Group

Aromatic C

9X

Aliphatic C

9X

C

9Cl

1.59

1.87

C

9Br

1.57

1.82

C

9I

1.40

1.65

C

9CH

2F

1.77

C

9CF

3

2.54

2.32

C

9CH

2Cl

1.85

1.95

C

9CHCl

2

2.04

1.94

C

9CCl

3

2.11

1.57

C

9CH

2Br

1.86

1.96

C 9C #N

4.05

3.4

C

9NC

3.5

3.5

C

9CH

2CN

1.86

2.0

C 9C "O

2.65

2.4

C

9CHO

2.96

2.49

C

9COOH

1.64

1.63

C

9CO

9CH

3

2.96

2.49

C

9CO

9OCH

3

1.83

1.75

C

9CO

9OC

2H

5

1.9

1.8

C

9OH

1.6

1.7

C

9OCH

3

1.28

1.28

C

9OCF

3

2.36

C

9OCOCH

3

1.69

C

9OC

6H

5

1.16

1.16

C

9CH

2OH

1.58

1.68

C

9NH

2

1.53

1.46

C

9NHCH

3

1.71

C

9N(CH

3 )2

1.58

0.86

C

9NHCOCH

3

3.69

C

9N(C

6H

5 )2

(0.3)

0.3

C

9NCO

2.32

2.8

C

9N

3

1.44

C

9NO

3.09

C

9NO

2

4.01

2.70

C

9CH

2NO

2

3.3

3.4

C

9SH

1.22

1.55

C

9SCH

3

1.34

1.40

C

9SCF

3

2.50

C

9SCN

3.59

3.6

C

9NCS

2.9

3.3

C

9SC

6H 5

1.51

1.5

C

9SF

5

3.4

C

9SOCF

3

3.88

(C

9)2SO 2

5.05

4.53

(C

9)2SO 2CH

3

4.73

(C

9)2SO 2CF 3

4.32

C

9SeH

1.08

C

9SeCH

3

1.31

1.32

C

9Si(CH

3 )3

0.44

0.4