title: cyclo-Tetra-μ-malato-κO,O',O'':O'''-tetra-kis[bis-(1H-benzimidazole-κN)cobalt(II)] eicosa-hydrate.
abstract: The title compound, [Co(4)(C(4)H(4)O(5))(4)(C(7)H(6)N(2))(8)]·20H(2)O, consists of tetra-nuclear Co(II) complexes and disordered uncoordinated water mol-ecules. The tetra-meric complex mol-ecule has symmetry. While two benzimidazole mol-ecules and a tridentate malate dianion coordinate a Co(II) ion, the carboxylate O atom from an adjacent malate dianion bridges the Co(II) ions to complete a distorted octa-hedral coordination geometry. The tridentate malate dianion chelates the Co(II) ion, and the chelate six- and five-membered rings show half-chair and envelope configurations, respectively. A face-to-face separation of 3.494 (9) Å between parallel benzimidazole ligands indicates the existence of π-π stacking between adjacent complexes. The crystal structure also involves N-H⋯O and O-H⋯O hydrogen bonds.
authors.affiliation: Department of Chemistry, Zhejiang University, People's Republic of China.
authors.forename: Jun-Hua
authors.initials: JH
authors.lastname: Li
authors.forename: Jing-Jing
authors.initials: JJ
authors.lastname: Nie
authors.forename: Jian-Rong
authors.initials: JR
authors.lastname: Su
authors.forename: Duan-Jun
authors.initials: DJ
authors.lastname: Xu