Group Contributions to ΔHf

°(g) and S°(g) at 298 K*

GroupΔHf° (kJ/mol)S° (J/mol K)
C-(H)3(C)-42.1127.1
C-(H)2(C)2-20.739.4
C-(H)(C)3-7.9-50.4
C-(C)42.1-146.7
Cd-(H)226.2115.4
Cd-(H)(C)35.933.3
Cd-(C)243.2-53.1
Cd-(Cd)(H)28.326.7
Cd-(Cd)(C)37.1-61.0
[Cd-(CB)(H)]28.326.8
Cd-(CB)(C)36.1-61.0
GroupΔHf° (kJ/mol)S° (J/mol K)
[Cd-(Ct)(H)]28.326.8
C-(Cd)(C)(H)2-19.941.0
C-(Cd)2(H)2-17.942.6
C-(Cd)(C)37.0-145.1
Ca143.025.1
C-(Cd)(C)2(H)-6.2-48.9
C-(Cd)(CB)(H)2-17.942.6
C-(CB)(C)2(H)-4.1-51.0
C-(CB)(C)(H)2-20.338.9
C-(CB)(C)311.8-147.0
CB-(H)13.848.2
GroupΔHf° (kJ/mol)S° (J/mol K)
CB-(C)23.0-32.1
CB-(Cd)23.7-32.6
[CB-(Ct)]23.8-32.6
CB-(CB)20.7-36.1
C-(Ct)(C)2(H)-7.2-46.8
C-(Ct)(C)(H)2-19.843.0
Ct-(C)115.226.5
Ct-(H)112.6103.2
Ct-(Cd)122.126.9
Ct-(CB)122.126.9

*The subscripts "d" and "t" designate carbon atoms in carbon-carbon double and triple bonds; "a", an allenic carbon; "B", an aromatic carbon; "A", a nitrogen atom in a nitrogen-nitrogen double bond; and "I", a nitrogen atom in a nitrogen-carbon double bond. Bracketed values are estimated.

Reference: S.W. Benson, F.R. Cruickshank, D.M. Golden, G.R. Haugen, H.E. O'Neal, A.S. Rodgers, R. Shaw, and R. Walsh, Chem. Rev., 69, 279 (1969).