Slow Magnetic Relaxation Of Complexes Containing A Single Co~? Ion

Single molecular magnets(SMMs)are one of the the most important discoveries in the molecular magnetism in the past 30 years.Singel ion magnets(SIMs)have been of great interest as the researchers can futher explore their magnetic anisotropy and the details of the slow magnetic relaxation due to their simple structure.Although many Co? SIMs have been reported,the relation between their magnetic properties and structure is still undefined.In this research presented in this Dissertation,we study the slow magnetic relaxtion of several Co? complexes.The Dissertation is divided in four parts.Following the introduction to the transition metal SIMs found in recent years in chapter one,our results on Co? SIMs are presented in the subsequent chapters.In chapter one,the concept of SMMs and the research on SIMs based on the transition metal ion were summarized.In chapter two,the magnetic properties of three neutral Co? complexes[(C5H5)2Co3[P(O)(OMe2)2]6](1),[(C5H5)2Co3[P(O)(OEt2)2]6](2),[(C5H5)2CO3[P(O)(OiPr2)2]6](3)with similar structures were studied.The central Co?is coordinated by six oxygen atoms from[P(O)(OR2)2]groups,forming the slightly distorted octahedral geometry.They exhibit field-induced slow magnetic relaxtion.Since the two terminal Co? is diamagnetic while the central Co? is paramagnetic,the three complexes are the Co? single ion magnets(SIMs).In chapter three,three seven-coordinated Co? complexes[(bpy)Co(NO3)2(CH3CN)](4),[(phen)Co(N03)2(CH3CN)](5),[(pndn)Co(NO3)2(CH3CN)]·6H2O(6)with three different ligands 2,2'-dipyridine,1,10-phenanthroline,and pyrazino[2,3-f][1,10]phenanthroline were synthesized and characterized.They possess a pentagonal pyramidal geometry around the Co? ions.Complexes 5,6 show slow magnetic relaxtion behavior under a applied dc field while complex 4 does not.In chapter four,the magnetic properties of a low-spin Co? complex[Co(12-TMC)(CH3CN)(ClO4)2](7)has been studied.It has a square-pyramidal geometry around the Co(II)center and exhibits the field-induced slow magnetic relaxation.