text: Selenols are structurally similar to thiols, but the  bond is about 8% longer at 196 pm. The  angle approaches 90°. The bonding involves almost pure p-orbitals on Se, hence the near 90 angles. The  bond energy is weaker than the  bond, consequently selenols are easily oxidized and serve as H-atom donors. The Se-H bond is much weaker than the  bond as reflected in their respective bond dissociation energy (BDE). For Benzeneselenol|, the BDE is 326 kJ/mol, while for Benzenethiol|, the BDE is 368 kJ/mol.
  Selenols are about 1000 times stronger acids than thiols: the pK of Methaneselenol| is 5.2 vs 8.3 for Methanethiol|. Deprotonation affords the selenolate anion, , most examples of which are highly nucleophilic and rapidly oxidized by air.
  The boiling points of selenols tend to be slightly greater than for thiols. This difference can be attributed to the increased importance of stronger van der Waals bonding for larger atoms. Volatile selenols have highly offensive odors.