The crystal structure of vulgarone B (2,6,6,11-tetra­methyl­tri­cyclo­[5.4.0.0^2,8]­undec-10-en-9-one), a carbocyclic sesquiterpene with the formula C₁₅H₂₂O, is reported. All intramolecular geometric parameters are as expected. The mol­ecule contains a four-membered ring, in which all atoms are stereogenic. The 1,3 and 2,4 atoms of this cyclo­butane are bridgehead C atoms which form part of six-membered and seven-membered rings.

The crystal structure of 3-penta­fluoro­thio­propionic acid, C₃H₅F₅O₂S, is reported. In the solid, the acid forms a dimeric unit, in which two mol­ecules are held together by strong hydrogen bonds. The two mol­ecules are arranged across an inversion center. The average literature structural parameters for the organic/organometallic penta­fluoro­thio group are reported, and a short discussion of the geometry of this mol­ecule in this context is given.