Hydrogen bond
Hydrogen bonds can vary in strength from weak (1–2 kJ mol) to strong (161.5 kJ mol in the ion ). Typical enthalpies in vapor include:
Helium compounds
The HeHN molecule is linear. The He-H bondlength is 1.72 Å. It has an infrared band, due to B-H stretching, with a base at 3158.42 cm. The binding energy is 378 cm in the 000 vibrational state, and 431 cm in the 100 vibrational state. HeHN is also known. One helium atom is linked to a hydrogen, and the other is less tightly bound.