Table 1. The most important theoretical data of the five states, including RC–Cs (Å) and vibrational frequencies (ωe, cm–1), together with their experimental data (shown in bracket).
| 1Σ+g | 3Πu | 3Σ+u | 3Σ–g | 1Πu | |
| R C–C (Å) | 1.255 (1.243) | 1.330 (1.312) | 1.224 (1.230) | 1.384 (1.369) | 1.338 (1.318) |
| ΔErelat. (kcal mol–1) | –142.5 (–142) | –131.8 | –114.9 | –113.1 | –104.7 |
| ω e (cm–1) | 1839 (1855) | 1599 (1641) | 1975 (2084) | 1436 (1470) | 1553 (1608) |
| Dominant configuration | KK2σ2g | KK2σ2g2σ2u | KK2σ2g1π2xu | KK2σ2g2σ2u | KK2σ2g2σ2u |
| 1π2xu1π2yu2σ2u | 1π2xu1παyu3σαg | 1π2yu2σαu3σβg | 3σ2g1παxu1παyu | 1π2xu1παyu3σβg | |
| EBO | 2.15 | 1.90 | 2.74 | 1.92 | 1.90 |
| Weight | 71.0% | 87.5% | 85.1% | 93.0% | 89.9% |
| One electron density | 0.014e (3σu) | 0.020e (3σu) | 0.016e (3σu) | 0.026e (3σu) | 0.027e (3σu) |
| 0.115e (1πyg) | 0.074e (1πyg) | 0.109e (1πyg) | 0.048e (1πyg) | 0.041e (1πyg) | |
| 0.115e (1πxg) | 0.098e (1πxg) | 0.109e (1πxg) | 0.048e (1πxg) | 0.097e (1πxg) | |
| 0.393e (3σg) | 0.965e (1πyu) | 0.976e (3σg) | 0.990e (1πxu) | 0.985e (1πyu) | |
| 1.602e (2σu) | 1.045e (3σg) | 1.031e (2σu) | 0.990e (1πyu) | 1.023e (3σg) | |
| 1.888e (1πyu) | 1.905e (1πxu) | 1.891e (1πyu) | 1.956e (2σu) | 1.912e (1πxu) | |
| 1.888e (1πxu) | 1.910e (2σu) | 1.891e (1πxu) | 1.966e (3σg) | 1.933e (2σu) | |
| 1.984e (2σg) | 1.982e (2σg) | 1.977e (2σg) | 1.978e (2σg) | 1.982e (2σg) |