title: R4/4 (30) rectangular rings in 2,5-dioxopiperazine-1,4-diacetic acid.
abstract: Molecules of the title 2,5-dioxopiperazinedione derivative, C(8)H(10)N(2)O(6), occupy centres of symmetry in the crystal structure. The six-membered ring has an almost planar conformation, with the substituent on nitrogen nearly perpendicular to the ring. The ideal geometry of the isolated molecule, as determined by ab initio HF-LCAO quantum-mechanical calculations, is slightly more puckered than that observed in the solid state. In the crystal structure, a strong hydrogen bond joins neighbouring molecules, thus forming a network of rectangular R(4)(4)(30) rings.
authors.affiliation: CEMDRX, Departamento de Física, Faculdade de Ciências e Tecnologia, Universidade de Coimbra, P-3004-516 Coimbra, Portugal. manuela@pollux.fis.uc.pt
authors.forename: Manuela
authors.initials: M
authors.lastname: Ramos Silva
authors.forename: Ana
authors.initials: A
authors.lastname: Matos Beja
authors.forename: Jose Antonio
authors.initials: JA
authors.lastname: Paixão
authors.forename: Abilio J F N
authors.initials: AJ
authors.lastname: Sobral
authors.forename: Lucia M L
authors.initials: LM
authors.lastname: Cabral
authors.forename: A M d'A
authors.initials: AM
authors.lastname: Rocha Gonsalves