[2] A hydrogen bond normally has one proton, but a hydrogen bond with a Bjerrum defect will have either two protons (D defect, from "doppel" in German, meaning "double"[3]) or no proton (L defect, from "leer" in German, meaning "empty"[3]).
[4] The unfavorable defect strain is resolved when a water molecule pivots about an oxygen atom to produce hydrogen bonds with single protons.
[5] Nonpolar molecules such as methane can form clathrate hydrates with water, especially under high pressure.
In such cases the guest-host hydrogen bonds result in the formation of L-type Bjerrum defect in the clathrate lattice.
[6] Oxygen atoms (in alcohol or carbonyl functional groups) and nitrogen atoms (in amine functional groups) in the guest molecules lead to transient hydrogen bonds and misoriented water molecules in the hydrate lattice.