Five New Zinc Phosphite Structures: Tertiary Building Blocks in the Construction of Hybrid Materials

The syntheses and structures of five new zinc phosphites [Zn(HPO(3))(C(4)H(6)N(2))] (1), [Zn(2)(HPO(3))(2)(C(10)H(10)N(2))(2)](2) (2), [Zn(HPO(3))(C(14)H(14)N(4))(0.5)] (3), [Zn(2)(HPO(3))(2)(C(14)H(14)N(4))].0.4H(2)O (4), and [Zn(2)(HPO(3))(2)(C(14)H(14)N(4))] (5) are reported. In compounds 1-3, the zinc atoms are ligated by 1-methylimidazole, 1-benzylimidazole, and 1,4-bis(imidazol-1-ylmethyl)benzene, respectively, while compounds 4 and 5 are synthesized in the presence of the same bifunctional ligand, 1,3-bis(imidazol-1-ylmethyl)benzene. The inorganic framework of compound 1 is composed of vertex-shared ZnO(3)N and HPO(3) tetrahedra that form 4-rings, which, in turn, are linked to generate a one-dimensional ladder structure. In 2, the inorganic framework is composed of 4-rings and 8-rings to form the well-known 4.8(2) 2D network. This is connected via C-H...pi interactions between 1-benzylimidazole ligand to generate a pseudo-pillared-layer structure. In 3, the inorganic framework again has the 4.8(2) topology pillared by the bis(imidazole) ligand, 1,3-bis(imidazol-1-ylmethyl)benzene. In 4, a new layer pattern is observed. Specifically, three edge-sharing 4-rings form triple-fused 4-rings. These tertiary building units are further connected to form 12-rings. The alternating triple 4-rings and 12-rings form a previously unknown 2D inorganic sheet. The sheets are joined together by the bis(imidazole) ligand, 1,3-bis(imidazol-1-ylmethyl)benzene, to generate a 3D pillared-layer structure. In 4, benzene rings and imidazole rings stack in a zigzag pattern in the interlayer space. A significant role for the triple 4-ring tertiary building unit in the formation of hybrid inorganic/organic metal phosphite structures is proposed for 4 and 5. In 5, the triple 4-rings fuse to give a 1D stair-step structure. Calculations show that the triple 4-ring pattern observed in the linear ladder structure of 1 is more stable than that in the stair step pattern of 5.