This molecule contains three electrons, two from one helium atom and one from the other helium (He+) ion. The molecular orbital electronic configuration of the molecule is:
Its bond dissociation energy has been found to be 242 kJ mol-1. The molecule is expected to be paramagnetic and the same has been experimentally observed also.
Similarly, the molecular orbital configurations of Li2, Be2, B2 and C2 molecules can be written as given below:
| Molecule | M.O configuration | Bond Order | Magnetic character |
|---|---|---|---|
| Li2 | KK (σ2s)2 | 1 | Diamagnetic |
| Be2 | KK (σ2s)2σ*2s)2 | 0 | Molecule does not exist |
| B2 | KK (σ2s)2σ*2s)2(π2px)1(π2py)1 | 1 | Paramagnetic |
| C2 | KK (σ2s)2σ*2s)2(π2px)2(π2py)2 | 2 | Diamagnetic |
Here KK corresponds to (s1s)2 (s*1s)2
