Group Contributions to ΔHf
°(g) and S°(g) at 298 K*
| Group | ΔHf° (kJ/mol) | S° (J/mol K) |
|---|---|---|
| C-(H)3(C) | -42.1 | 127.1 |
| C-(H)2(C)2 | -20.7 | 39.4 |
| C-(H)(C)3 | -7.9 | -50.4 |
| C-(C)4 | 2.1 | -146.7 |
| Cd-(H)2 | 26.2 | 115.4 |
| Cd-(H)(C) | 35.9 | 33.3 |
| Cd-(C)2 | 43.2 | -53.1 |
| Cd-(Cd)(H) | 28.3 | 26.7 |
| Cd-(Cd)(C) | 37.1 | -61.0 |
| [Cd-(CB)(H)] | 28.3 | 26.8 |
| Cd-(CB)(C) | 36.1 | -61.0 |
| Group | ΔHf° (kJ/mol) | S° (J/mol K) |
|---|---|---|
| [Cd-(Ct)(H)] | 28.3 | 26.8 |
| C-(Cd)(C)(H)2 | -19.9 | 41.0 |
| C-(Cd)2(H)2 | -17.9 | 42.6 |
| C-(Cd)(C)3 | 7.0 | -145.1 |
| Ca | 143.0 | 25.1 |
| C-(Cd)(C)2(H) | -6.2 | -48.9 |
| C-(Cd)(CB)(H)2 | -17.9 | 42.6 |
| C-(CB)(C)2(H) | -4.1 | -51.0 |
| C-(CB)(C)(H)2 | -20.3 | 38.9 |
| C-(CB)(C)3 | 11.8 | -147.0 |
| CB-(H) | 13.8 | 48.2 |
| Group | ΔHf° (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 | -19.8 | 43.0 |
| Ct-(C) | 115.2 | 26.5 |
| Ct-(H) | 112.6 | 103.2 |
| Ct-(Cd) | 122.1 | 26.9 |
| Ct-(CB) | 122.1 | 26.9 |
*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).