The first example of unique coordination induced intramolecular pancake bonding was achieved through the reduction of two bis(pyrazolyl)-tetrazine ligands,affording[M_(2)^(Ⅲ)(μ-(bpytz)_(2))(THMD)4](M=Dy,Y;bpytz=3,6-...The first example of unique coordination induced intramolecular pancake bonding was achieved through the reduction of two bis(pyrazolyl)-tetrazine ligands,affording[M_(2)^(Ⅲ)(μ-(bpytz)_(2))(THMD)4](M=Dy,Y;bpytz=3,6-bis(3,5-dimethyl-pyrazolyl)-1,2,4,5-tetrazine;TMHD=2,2,6,6-tetramethyl-3,5-heptanedionate).To provide a cohesive magneto-structural correlation,the mono bis(pyrazolyl)-tetrazine bridged congener[Dy_(2)^(Ⅲ)(μ-bpytz)(THMD)6]·4(C6H6)was also isolated.Both metal complexes exhibit single-molecule magnet behaviour under an applied dc field.展开更多
A combination of high-performing lanthanide metallocenes and tetrazine-based radical ligands leads to a new series of radical-bridged dinuclear lanthanide metallocenes;[(Cp^(*)_(2)Ln^(Ⅲ))_(2)(bpytz^(•−))][BPh_(4)](wh...A combination of high-performing lanthanide metallocenes and tetrazine-based radical ligands leads to a new series of radical-bridged dinuclear lanthanide metallocenes;[(Cp^(*)_(2)Ln^(Ⅲ))_(2)(bpytz^(•−))][BPh_(4)](where Ln=Gd(1),Tb(2),Dy(3)and Y(4);Cp_(*)=pentamethylcyclopentadienyl;bpytz=3,6-bis(3,5-dimethyl-pyrazolyl)-1,2,4,5-tetrazine).The formation of the radical species is achieved via a controlled,stepwise synthesis and verified in all complexes by X-ray crystallography and SQUID magnetometry,as well as EPR spectroscopy of 4.Through the judicious choice of the Cp_(*)ancillary ligands and by taking advantage of the steric effects imposed by their bulkiness,we were able to promote the trans coordination mode of the bpytz^(•−)radical anion that enables stronger magnetic exchange coupling compared to the cis fashion.This yields a J_(Gd–rad)=−14.0 cm^(−1) in 1,which is the strongest exchange coupling observed in organic monoanionic radical-bridged lanthanide metallocene systems.The strong Ln-rad exchange coupling was further confirmed by high-frequency EPR(HF-EPR)spectroscopy and broken-symmetry(BS)density functional theory(DFT)calculations.This combined with the highly anisotropic nature of Tb^(Ⅲ) and Dy^(Ⅲ) ions in 2 and 3,respectively,leads to strong SMM behavior and slow relaxation of the magnetization at zero fields.展开更多
基金the University of Ottawa,the CFI,the NSERC and the Academy of Finland(projects 315829,320015)for their financial supportConselho Nacional de Desenvolvimento Científico e Tecnológico(CNPQ,201395/2014-6)for a PhD scholarship.
文摘The first example of unique coordination induced intramolecular pancake bonding was achieved through the reduction of two bis(pyrazolyl)-tetrazine ligands,affording[M_(2)^(Ⅲ)(μ-(bpytz)_(2))(THMD)4](M=Dy,Y;bpytz=3,6-bis(3,5-dimethyl-pyrazolyl)-1,2,4,5-tetrazine;TMHD=2,2,6,6-tetramethyl-3,5-heptanedionate).To provide a cohesive magneto-structural correlation,the mono bis(pyrazolyl)-tetrazine bridged congener[Dy_(2)^(Ⅲ)(μ-bpytz)(THMD)6]·4(C6H6)was also isolated.Both metal complexes exhibit single-molecule magnet behaviour under an applied dc field.
基金support from the US Department of Energy,Basic Energy Sciences(DE-SC0020260)the National High Magnetic Field Laboratory is supported by the US National Science Foundation(DMR-1644779)+4 种基金the State of Florida.A.M.acknowledges funding provided by the Academy of Finland(grant no.332294)the University of Oulu(Kvantum Institute)the Academy of Finland(projects 315829 and 345484)for the financial supportthe CSC-IT Centre for Science in Finland,the Finnish Grid and Cloud Infrastructure(persistent identifier urn:nbn:fi:research-infras-2016072533)Prof.H.M.Tuononen(University of Jyväskylä)for providing computational resources for the project.
文摘A combination of high-performing lanthanide metallocenes and tetrazine-based radical ligands leads to a new series of radical-bridged dinuclear lanthanide metallocenes;[(Cp^(*)_(2)Ln^(Ⅲ))_(2)(bpytz^(•−))][BPh_(4)](where Ln=Gd(1),Tb(2),Dy(3)and Y(4);Cp_(*)=pentamethylcyclopentadienyl;bpytz=3,6-bis(3,5-dimethyl-pyrazolyl)-1,2,4,5-tetrazine).The formation of the radical species is achieved via a controlled,stepwise synthesis and verified in all complexes by X-ray crystallography and SQUID magnetometry,as well as EPR spectroscopy of 4.Through the judicious choice of the Cp_(*)ancillary ligands and by taking advantage of the steric effects imposed by their bulkiness,we were able to promote the trans coordination mode of the bpytz^(•−)radical anion that enables stronger magnetic exchange coupling compared to the cis fashion.This yields a J_(Gd–rad)=−14.0 cm^(−1) in 1,which is the strongest exchange coupling observed in organic monoanionic radical-bridged lanthanide metallocene systems.The strong Ln-rad exchange coupling was further confirmed by high-frequency EPR(HF-EPR)spectroscopy and broken-symmetry(BS)density functional theory(DFT)calculations.This combined with the highly anisotropic nature of Tb^(Ⅲ) and Dy^(Ⅲ) ions in 2 and 3,respectively,leads to strong SMM behavior and slow relaxation of the magnetization at zero fields.
