Ligand-Directed Construction of Zn(II) Complexes from Zero-Dimensional Metallomacrocycle to One-, Two-, and Three-Dimensional Coordination Polymers Based on N-Donor and β-Diketone Bifunctional Ligands

Abstract

Six new complexes [Zn2(L1)4]·2H2O·DMF (1), [Zn2(L2)4]3·13H2O (2), [Zn1.5(L3)3]2 (3), Zn(L4)2·2H2O (4), Zn(L5)2·2CHCl3 (5), and [Zn(L6)2]2 (6) (where HL1 = 1-(4-(1H-imidazol-1-yl)phenyl)butane-1,3-dione, HL2 = 1-(4-(1H-benzimidazol-1-yl)phenyl)butane-1,3-dione, HL3 = 1-(4-(1H-pyrazol-1-yl)phenyl)butane-1,3-dione, HL4 = 1-(3-(1H-imidazol-1-yl)phenyl)butane-1,3-dione, HL5 = 1-(3-(1H-benzimidazol-1-yl)phenyl)butane-1,3-dione and HL6 = 1-(3-(1H-pyrazol-1-yl)phenyl)butane-1,3-dione) have been synthesized by the reaction of the bifunctional ligands and Zn(II) salts under similar experimental conditions. Structural analyses show that the ligands act as a tridentate and bind to two Zn(II) ions as a two-connected linker, generating a variety of geometries from discrete binuclear [2 + 2] metallomacrocycles (3 and 6) to a one-dimensional looped-chain coordination polymer (4) and two-dimensional (4,4) network (5) as well as three-dimensional frameworks with lvt (1) and NbO (2) topologies. The results demonstrate that the diverse structures are strongly dependent on the ligand geometries, due to the free rotation via the C–N/C–C bonds as well as the various coordinated sites of N-donor allowing the semirigidity ligands to take on appropriate conformations.