A novel threefold-interpenetrating primitive cubic network based on a dinuclear Zn2 node.

In the mixed-ligand metal-organic polymeric compound poly[[mu(2)-1,4-bis(imidazol-1-yl)benzene](mu(2)-terephthalato)dizinc(II)], [Zn(2)(C(8)H(4)O(4))(2)(C(12)H(10)N(4))](n) or [Zn(2)(bdc)(2)(bib)](n) [H(2)bdc is terephthalic acid and bib is 1,4-bis(imidazol-1-yl)benzene], the asymmetric unit contains one Zn(II) ion, with two half bdc anions and one half bib molecule lying around inversion centers. The Zn(II) ion is in a slightly distorted tetrahedral environment, coordinated by three carboxylate O atoms from three different bdc anions and by one bib N atom. The crystal structure is constructed from the secondary building unit (SBU) [Zn(2)(CO(2))(2)N(2)O(2)], in which the two metal centers are held together by two bdc linkers with bis(syn,syn-bridging bidentate) bonding modes. The SBU is connected by bdc bridges to form a two-dimensional grid-like (4,4)-layer, which is further pillared by the bib ligand. Topologically, the dinuclear SBU can be considered to be a six-connected node, and the extended structure exhibits an elongated primitive approximately cubic framework. The three-dimensional framework possesses a large cavity with dimensions of approximately 10 x 13 x 17 A in cross-section. The potential porosity is filled with mutual interpenetration of two identical equivalent frameworks, generating a novel threefold interpenetrating network with an alpha-polonium topology [Abrahams, Hoskins, Robson & Slizys (2002). CrystEngComm, 4, 478-482].