Group Contributions to ΔHf
°(g) and S°(g) at 298 K*
| Group | ΔHf° (kJ/mol) | S° (J/mol K) |
|---|---|---|
| [C-(N)(H)3] | -42.1 | 127.1 |
| C-(N)(C)(H)2 | -27.6 | 41.0 |
| C-(N)(C)2(H) | -21.7 | -48.9 |
| C-(N)(C)3 | -13.4 | -142.5 |
| C-(NA)(C)(H)2 | -23.0 | 41.0 |
| C-(NA)(C)2(H) | -13.8 | -48.9 |
| C-(NA)(C)3 | -7.9 | -145.0 |
| N-(C)(H)2 | 20.1 | 124.2 |
| N-(C)2(H) | 64.4 | 37.4 |
| N-(C)3 | 102.0 | -56.3 |
| N-(N)(H)2 | 47.6 | 121.8 |
| N-(N)(C)(H) | 87.4 | 40.2 |
| N-(N)(C)2 | 122.1 | -57.7 |
| N-(N)(CB)(H) | 92.4 | |
| NI-(C) | 89.0 |
| Group | ΔHf° (kJ/mol) | S° (J/mol K) |
|---|---|---|
| NI-(CB) | 69.8 | |
| CB-(CN) | 149.6 | 85.7 |
| NA-(H) | 104.9 | 112.0 |
| NA-(C) | 135.8 | 33.4 |
| N-(CB)(H)2 | 20.1 | 124.2 |
| N-(CB)(C)(H) | 62.3 | |
| N-(CB)(C)2 | 109.5 | |
| N-(CB)2(H) | 68.1 | |
| CB-(N) | -2.1 | -40.5 |
| NA-(N) | 96.1 | |
| CO-(N)(H) | -123.7 | 146.0 |
| CO-(N)(C) | -137.1 | 67.7 |
| N-(CO)(H)2 | -62.3 | 103.2 |
| N-(CO)(C)(H) | -18.4 | 16.3 |
| N-(CO)(CB)(H) | 1.7 | |
| N-(CO)2(H) | -77.3 |
| Group | ΔHf° (kJ/mol) | S° (J/mol K) |
|---|---|---|
| N-(CO)2(C) | 24.7 | |
| N-(CO)2(CB) | -2.1 | |
| C-(CN)(C) (H)2 | 94.0 | 168.0 |
| C-(CN)(C)2(H) | 107.8 | 82.8 |
| C-(CN) (C)3 | -11.7 | |
| C-(CN)2(C)2 | 118.7 | |
| Cd-(CN)(H) | 156.3 | 152.9 |
| Cd-(CN)2 | 351.5 | |
| Ct-(CN) | 266.7 | 148.0 |
| Cd-(NO2)(H) | 185.8 | |
| C-(NO2)(C) (H)2 | -63.1 | 202.3 |
| C-(NO2)(C)2(H) | -66.0 | 112.4 |
| C-(NO2)(C)3 | 16.3 | |
| C-(NO2)2(C)(H) | -62.3 | |
| O-(NO)(C) | -24.7 | 175.1 |
| O-(NO)2(C) | -81.1 | 202.7 |
*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).