Table 11.
The A-A’ energetics of the acetylenic triple bond in various alkynes. Note that the sum only includes the two carbons. The method is 2PDM-M/CCSD(T) and the basis set is uncontracted 6–31 + G(d, p) with the outer s-function deleted from the carbon basis set. The C2 atom is marked as bold in the chemical formulae. Units: kJ/mol
| Molecule/atom | C1 | C2 | H | sum |
|---|---|---|---|---|
| HC ≡ CH | 134.7 | 134.7 | 33.4 | 269.4 |
| CH3C ≡ CH | 144.6 | 136.7 | 34.6 | 281.3 |
| CH3C ≡ CCH3 | 147.2 | 147.2 | 294.4 | |
| C2H5C ≡ CH | 145.3 | 138.0 | 34.9 | 283.6 |
| C2H5C ≡ CCH3 | 147.7 | 147.2 | 294.8 | |
| C3H7C ≡ CH | 144.4 | 138.3 | 35.1 | 282.6 |
| HC ≡ C-C ≡ CH | 148.8 | 158.4 | 35.9 | 307.2 |
| Average (SD) | 143.4 (5.2) | 141.9 (7.8) | 34.5 (0.9) | 285.3 (12.2) |