Study On The Crystal Structure And Properties Of 3d And 4f Low-Core Cluster Element Complexes With Potential Coordination Assembling Points By Using Multiple Bidentate Ligands

Single molecule magnets have attracted more attention because of their potential applications in high density information storage,molecular spin electronics,quantum computing and other fields.The substance which can be used as a single molecule magnet carrier may be an ion,a radical,an organic substance,a cluster compound,etc However,a single molecule magnet must have the following two conditions:1.There is a significant negative anisotropy;2.It has a large ground state spin.Although many high-core clusters are reported,however,most of these high-nuclear clusters were synthesized by one-step synthesis,and the high-nuclear cluster obtained by one-step synthesis is highly contingent.Therefore,the rational synthesis of high-quality cluster with excellent characteristics is still a major challenge.Using the secondary primers with potential coordination assembly points to obtained high-core clusters by conditional response and stage assembly,first,a series of precursors with potential assembly capabilities should be obtained.Most of these assembled precursors have active coordination assembly points(such as bare or weakly coordinated metal ions,uncoordinated or weakly coordinated coordination atoms,etc.),which is a necessary condition for further assembly.This paper focuses on the use of two rigid multi-bite chelating ligands and different metal centers,and synthesizes a series of different low-nuclear complexes with further assembly potential.These low-nucleus cluster-based complexes can be used as primers to construct primers and use the active coordination assembly points on their clusters to further assemble and synthesize high-core cluster-based complex,and prepare them for the subsequent rational construction of high-core cluster-based complex aggregates.In this paper,we use two multiple bidentate chelate ligands 3-(myridin-2-yl)-5-(2-phenol-6-yl)-1H-1,2,4-triazol(mpt),3-(myridin-2-yl)-5-(2-methoxyphenol-6-yl)-1H-1,2,4-triazol(mmpt) as ligand,six rare earth complexes were synthesized.Among them,the complex 1 is a mononuclear cerium complex,the central metal Ce(?)is used in the nine coordination of the anti-triangular prism coordination geometry,in this complex,the ligand is not involved in the coordination of pyrimidine nitrogen atom and the adjacent triazole nitrogen is a potential coordination site,which can be further coordinated with the metal,is a precursor with an assembled property.Complexes 2-4 are tetranuclear dysprosium complexes,tetranuclear gadolinium complexes and tetranuclear erbium complexes,respectively.By analyzing their structures,it is found that the metal atoms not only pass through the hydroxyl groups and the triazoles on the N-N bond bridge,but also through the ?₃-OH oxygen atoms bridged,and the ligand is not involved in the coordination of the pyrimidine nitrogen atoms and adjacent triazole nitrogen atoms on the potential coordination point,can further coordinated with the metal,is a precursor with assembly properties.Complexes 5 and 6 are six nuclears dysprosium,hexahedral erbium complexes.The bridging mode of the central atom is the same as that of the complex 2-4,and the nitrogen atom on the ligand which is not involved in the coordination pyrimidine nitrogen atom and the adjacent triazole is a potential coordination point which can be further coordinated with the metal,it is a precursor with assembly properties.To investigate the precursors with assembled properties,we obtained nine cobalt complexes with the two ligands:Co(mpt)₂Cl₂ (7);Co(mpt)₂·(H₂O)₂ (8);[Co(mpt)]_n (9);[Co(NO₂-mpt)(CH₃OH)]_n (10);[Co(mpt)(CH₃CN)]_n (11);[Co₂(mpt)₂(DMF)]_n (12);[Co₂(NO₂-mpt)₂(4,4-bpy)]_n·CH₃OH (13);[Co₃(mpt)₂Cl₂]_n (14);Co₂(mmpt)₂·H₂O (15),The structure of the complex is analyzed.It is found that the complex 7?8 is a mononuclear structure with unallocated atoms,which can be further coordinated with the metal under suitable conditions and can be used as the assembly precursor.Complexes 9-13 are complexes of one-dimensional chain structures in which complexes 9-12 are based on dinuclear cobalt and are bridged by two oxygen atoms on the phenolic hydroxyl groups to form two adjacent dinuclear cobalt,and the complex 13 is a double-core cobalt element and bridging another dinuclear cobalt element through the oxygen atom on the phenolic hydroxyl group to form a tetranuclear cobalt element,the tetranuclear cobalt element is further passed through 4,4-bpy bridge to form a one-dimensional chain structure.Further analysis revealed that in these complexes,the nitrogen atoms on the ligands that did not participate in coordination and the nitrogen atoms on the adjacent triazoles were potential coordination sites and could be further coordinated with the metal,which was of an assembled nature assembly.Fortunately,we obtained an example of a three-dimensional cobalt complex 14,which is based on dinuclear cobalt and forms a one-dimensional chain by bridging two adjacent nucleu of cobalt nucleotides on the hydroxyl groups of the ligand phenolic hydroxyl groups.The pyrimidine nitrogen atom and the nitrogen atom of the triazole in the one-dimensional chain are further coordinated with the CoCl₂ motif to form a three-dimensional structure.In addition,we finally synthesize other low-core cluster complexes 16-20 with different properties of assembling properties.They all have potential coordination sites,which can be further coordinated with the metal and are primitive elements with assembly properties.Prepare for the study of assembly.