Studies On The Slow Relaxation Behavior Of Antiprismatic Co(Ⅱ) And Mn(Ⅱ) Complexes

Molecular magnetic materials with bistability exhibit different relaxation properties,which have broad application prospects in high density information storage,spintronics,quantum computation and so on.They have become a hot research topic in the fields of physics,chemistry and materials.Transition metal complexes exhibiting slow magnetic relaxation are of great significance for the study of single molecule magnets(SMMs)and quantum bits.However,the research on the magneto-structure relationship and its mechanism still needs to be improved,especially the influence of environmental effects such as phonon bottleneck on slow relaxation behavior needs to be further studied.Herein,transition metal complexes with specific structures have been syntheslized and their structures and magnetic properties have been characterized to give a further study from the perspective of magneto-structural relationship and relaxation mechanism.The research results are as follow:1.Using KTp(potassium hydridotris(pyrazole)borate)and KpzTpMe(potassium tetra(3-methylpyrazole)borate)as ligands,four Co(Ⅱ)antitrigonal complexes were synthesized.Their bond lengths,bond angles and packing arrangement were different.All four complexes exhibited field-induced slow relaxation.It was found that the molecular packing arrangement in the cell may be the main factor affecting its slow relaxation behavior.In addition,all the Co(Ⅱ)complexes with trigonal prismatic and trigonal antiprismatic configurations published in recent years have been investigated.The relationship between torsion angle φ and anisotropy has been summarized based on the experimental results and the calculation results of model molecules.2.Two Mn(Ⅱ)complexes were synthesized using KTp(potassium hydridotris(pyrazole)borate)and KTp*(potassium hydridotris(3,5dimethylpyrazole)borate)as ligands.Structural characterization shows that it is a trigonal antiprismatic configuration.Magnetic tests show that it exhibits slow relaxation behavior under an applied magnetic field.It is intriguing that the polycrystalline samples and powder samples exhibit different relaxation behavior,which may be due to the phonon bottleneck effect.