Construction And Magnetic Research Of Polynuclear Metal Cluster Based On Tricyano And Octacyano-building Units

Recently,the design and construction of polynuclear metal cluster with large ground spin value has attracted increasing attention in chemistry,physics and materials fields,due to its potential applications in high density information storage,quantum computer,and magnetic switch.Although great progress has been seen in the design and synthesis of polynuclear metal clusters,two problems still are remain.One is that the relationship between the structure and magnetic properties of polynuclear metal clusters is not very clear.The other is the controlling of structure and macroscopic magnetic properties of the polynuclear metal clusters in assembly processes.Herein,controllable synthesis of molecular magnets has been realized by changing the geometrical configuration of building units.The use of different auxiliary ligands adjusts the coordination environment around the spin carriers and controls the structure of polynuclear metal clusters.The magnetic properties of polynuclear molecular magnets are controlled by introducing different transition metal ions.The main research results are as follows:(1)The three coordination sites of transition metal ions CuII,CoII and NiII were occupied by the tridentate chelating ligands and the remaining sites are coordinated by three tricyanometalate [FeIII(Tp*)(CN)3]-,[FeIII(Tp)(CN)3]-or [FeIII(pz Tp)(CN)3]-building units with different steric hindrance.Two trinuclear FeIII2CuII(1)and FeIII2CoII(2)metal clusters and two tetranuclear FeIII2CoII2(3)and FeIII2NiII2(4)clusters have been designed and synthesized by the selected building units.Magnetic analyses suggest that compounds 1,2 and 4 exhibit ferromagnetic coupling interactions,while antiferromagnetic coupling dominates in compound 3.(2)Reaction of octacyanometalate [W(CN)8]3-and [Mo(CN)8]3-building units and transition metal ions FeII,CoII and NiII,three comounds have been obtained by self-assembly.The structure of molecular magnets are controlled by the selected ligands,in which compound 5 is a tetranuclear MoV2FeIII2 cluster while compound 6 with a two-dimensional layered structure.In particular,compound 7 is a high symmetrical fifteen nuclear WV6NiII9 cluster.Magnetic analyses indicate that antiferromagnetic coupling interactions occurred in compounds 5 and 6,while the ferromagnetic coupling dominates in compound 7.