title: Tris(ethylenediamine)cobalt(II) bis(tetra-hydroxypentaborate) dihydrate.
abstract: The novel pentaborate with a transition-metal complex as counter-cation and with water of crystallization, tris(ethylenediamine)cobalt(II) bis[4,4',6,6'-tetrahydroxy-2,2'-spirobi(cyclotriboroxane)(1-)] dihydrate, [Co(C(2)H(8)N(2))(3)][B(5)O(6)(OH)(4)](2)·2H(2)O, forms a three-dimensional supra-molecular framework through O-H⋯O hydrogen bonding among the [B(5)O(6)(OH)(4)](-) anions with large channels along the a axis in which the templating [Co(en)(3)](2+) cations (en = ethylenediamine) and water mol-ecules are located. The crystal packing is consolidated by additional O-H⋯O and N-H⋯O hydrogen bonds.
authors.affiliation: Department of Chemistry, Jining Normal College, Wulanchabu, Inner Mongolia, 012000, People's Republic of China.
authors.forename: Lizhen
authors.initials: L
authors.lastname: Zhao
authors.forename: Ping
authors.initials: P
authors.lastname: Li
authors.forename: Baoliang
authors.initials: B
authors.lastname: Cao