The first homoleptic oxovanadium(IV)–histidine complex {systematic name: [(S*)-α-amino-4-imidazole­propionato-κ³N,N,O][(S*)-α-amino-3-(1H-imidazol-3-ium-5-yl)propionato-κ²N,O]oxovanadium(IV) perchlorate monohydrate}, [V^IVO(C₆H₈N₃O₂)(C₆H₉N₃O₂)]ClO₄·H₂O, adopts a distorted octa­hedral structure where one L-histidine ligand coordinates to the vanadium(IV) center in a tridentate fashion as a monoanion and the other in a bidentate fashion leaving a protonated imidazole group as a pendent group.

The cis,syn,cis-tricyclic [2+2]-dimer of cyclo­octatetraene, C₁₆H₁₆, crystallizes in space group Pca2₁ with two mol­ecules in the asymmetric unit. An extensive network of weak C—Hπ(C=C) interactions between the two independent mol­ecules, A and B, as well as AA and BB interactions, are observed in the supramolecular assembly. The C—H groups point more towards one C atom than to the centre of the C=C bond. Notable among the interactions are bifurcated (cyclo­butane)C—HC=C contacts that span transannularly the eight-membered ring.