Syntheses And Structural Characterization Of Transition-metal Complexes Derived From Hydroxymethyl Pyrazole/triazole And Bipyrazole Ligands

Pyrazole (triazole) ligands are complicated and multifunctional organicligands and showed more colorful self-assembly chemistry on comparison withmonodentate ligands. Pyrazole (triazole)-based molecular self-assemblers have potentialapplications in catalysis, bionics, magnetism, electron transfer, optico-physicalcharactristics and so on. It is therefore very valuable to do research on this kind ofligands and their complexes. In the first part of this dissertation, the currentdevelopment in supramolecular chemistry and specifically the applications of pyrazole(triazole)-based ligands in self-assembly are briefly reviewed.In the second part of this dissertion, two bipyrazoles, 3,3',5,5'-tetramethyl-4,4'-bipyrazole (H₂mdpz) and 4,4'-methylenebis(3,5-dimethylpyrazole)(H₂mbdpz), andtheir transition-metal complexes were synthesized. Their physicochemical propertieswere characterized by the Elemental Analysis, Infared spectra and TG-DSC analyses.Single crystals of the ligand H₂mdpz·H₂O (1) and one cabalt complex,[Co(H₂mdpz)₂(H₂O)₂](NO₃)₂ (6), suitable for X-ray diffraction analysis, weresuccessfully grown and their structures were determined. The unit-cell parameters werelisted below: ligand 1 is tetragonal with space group I4(1)/acd and unit-cell parametersof a=24.8515(16) (?), b=24.8515(16) (?), c=14.9374(12) (?). Compound 6 ishexagonal with space group P6/mcc and unit-cell parameters of a=19.9217(14)(?), b=19.9217(14)(?), c=16.2258(17)(?) andγ=120°. The metal atom is coordinated by fournitrogen atoms each from one ligand and two oxygen atoms each from one nitrate anion,forming an eight-coordinate geometry. The infinite 2D layers are extended into 3Dnetwork by the hydrogen bonding between the ligand molecules and nitrate counterion,with the topology of the compound being 3²6².In the third part, two new ligands, (1-hydroxymethyl-3,5-dimethylpyrazole (pzOH)and 1-hydroxymethyltriazole (btzOH), and 11 transition-metal compounds derivedfrom were synthesized. These compounds were also undergone the Elemental Analysis,Infared spectra and TG-DSC analyses. The molecular structures of one compound werealso determined. The unit-cell parameter was listed below: compound 19 is monoclinic with space group P2(1)/n and unit-cell parameters of a=8.2008(12) (?), b=8.3865(12)(?), c=9.9672(14) (?) andβ=91.311(2)°.In summary, in this paper, two bipyrazole ligands, two N,O ligands and 21 newcompounds were synthesized and characterized. The structure characteristics of thesenew metal complexes have been studied through physicochemical characterisation.These results will provide certain theoretical basis for the studies of the properties ofthis type of ligands and their complexes.