Syntheses, Characterizations And Properties Of Metallacrowns Containing Bihydrazidate

Hydrazidate and its ramification are strong chelating ligands, which can form complexes with many metals. What't more, complexes of hydrazidate often exhibit better functions than ligands. These complexes have prodigious application values, such as magnetism and optical material, molecule recognize reagent, catalyse reagent, especially in biological activity aspect. Therefore, study of metallacrows of hydrazidate and its analogues is receiving greatly attention. So far, there are many reports about complexes of hydrazone and monohydrazidate, while fewer are reported about bihydrazidate and its complexes. Reports about metallacrowns in the literature are mostly concentrated in syntheses and research of its topological structure. But fewer are reported about high nuclear metallacrowns. The study of its diverse properties and potential function is not deep enough. Besides, N-acylsalicylhydrazidate ligand, which contains several donor atoms is a strong chelating agent, is very suitable for the preparation of metallacrowns. In this paper, we synthesized series of N-acylsalicylhydrazidate ligands. With coodinated with transition metal Mn (â…¢) /Fe (â…¢) using self-assembly method, we successfully synthesized six metallacrowns. These complexes were characterized by IR spectrum, and the crystal structures are determined by single crystal X- ray diffraction methods. The complexes are as follows:(1) [Mn₆ (C₁₀H₉N₂O₃)₆ (CH₃OH) ₆]·₆ H₂O(2) [Fe₆(C₁₀H₉N₂O₃)₆ (C₃H₇NO) ₆]·₆ CH₃OH(3) [Mn₆ (C₁₁H₁₁N₂O₃)₆ (CH₃CH₂OH)₆]·₃ C₃H₇NO·2CH₃CH₂OH(4) [Mn₁₆(C₁₄H₈N₂O₃F)1₆ (C₅H₅N)1₆](5) [Mn₁₀ (C₁₈H₁₇N2O₃)₈ (C₁₃H₁₅N₂O₃)₂(DMF)₁₀]·2DMF(6) [Mn₈ (C₁₂H₁₁N₂O₃)8 (DMA)₈] [Mn8 (C₁₂H₁₁N₂O₃)₈ (DMA)₆ (H₂O)₂]·2 DMA·5 H₂OAll the complexes were measured by X-ray diffraction and the crystal structures have been studied. Complexes 1-6 are all based on the structural unit of [-M-N-N-]. In the molecular configuration, all of the metal atoms have two different coordination environments: ? andΛconfiguration that alternately arranged to promote the formation of rings. Metals in the ring are often in distorted octahedral coordination geometry MN2O4. Metallacrowns are generally flat shape with oval cavity in the center. It was found that the end groups of the ligands have a direct impact on the size of metallacrowns. While N-acylsalicylhydrazides (L1, L2) with a sterically flexible Cα group yield 18-membered hexanuclear metallacrowns,α-branched N-acylsalicylhydrazides lead to 24-membered octanuclear manganese metallacrowns or 30-, 48-membered decanuclear manganese metallacrowns depending on the size of the N-acyl substituents. The magnetic properties of the metallacrowns are characterized by antiferromagnetic exchange interaction.