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

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.