A tetranuclear cubane-type complex[Co_(4)(ntfa)_(4)(CH_(3)O)_(4)(CH_(3)OH)_(4)](1)with a{Co_(4)O_(4)}core,and a mononuclear complex[Co(ntfa)_(2)(CH_(3)OH)_(2)](2)have been rationally obtained by adjusting the ratio of...A tetranuclear cubane-type complex[Co_(4)(ntfa)_(4)(CH_(3)O)_(4)(CH_(3)OH)_(4)](1)with a{Co_(4)O_(4)}core,and a mononuclear complex[Co(ntfa)_(2)(CH_(3)OH)_(2)](2)have been rationally obtained by adjusting the ratio of theβ-diketonate and Co(II)ions,with the synthetic processes being monitored by in situ microcalorimetry.Then,following synthetic conditions to obtain 2,but using three distinct N-donor coligands-2,2’-bipyridyl(bpy),6,6’-dimethyl-2,2’-bipyridyl(6,6-(CH_(3))_(2)-bpy)and 5,5’-dimethyl-2,2’-bipyridyl(5,5-(CH_(3))_(2)-bpy)-three novel mononuclear complexes have been obtained,[Co(ntfa)_(2)(bpy)_(2)](3),[Co(ntfa)_(2)(6,6-(CH_(3))_(2)-bpy)_(2)](4)and[Co(ntfa)_(2)(5,5-(CH_(3))_(2)-bpy)_(2)](5).The introduction of different capping coligands-as singlecrystal X-ray crystallography ascertains-fine-tunes the structures,with changes in both the distortion degree of the coordination geometry and the intermolecular interactions,which have a direct impact on the magnetic properties of these complexes.Magnetic investigations reveal field-induced single-ion magnet behavior in all complexes with distinct energy barriers(Ueff)-39.06(1),36.65(2),36.32(3),28.26(4)and 15.85 K(5).Magnetic experiments together with HF-EPR measurements and theoretical calculations demonstrate that 2 features easy-axis magnetic anisotropy(D=-60.48 cm^(-1)),whereas 3-5 show easy-plane magnetic anisotropies-D=+70.77 cm^(-1) for 3,+35.71 cm^(-1) for 4,and+51.28 cm^(-1) for 5.To our knowledge,such reversal of anisotropic nature driven by coligands is unprecedented.展开更多
基金The work was carried partly out under the auspices of the Ministry of Education, Youth ＆ Sports of the Czech Republic as a part of its research project No. MSM 0021627501 and partly out under support from the Ministry of Industry ＆ Trade of the Czech Republic as a part of
its Research project TANDEM No. FT-TA/049.
基金support from the National Natural Science Foundation of China(21863009,U20A2073)the Natural Science Foundation of Ningxia Province(2020AAC02005)+5 种基金the Discipline Project of Ningxia(NXYLXK2017A04)the Guizhou Education Department Youth Science and Technology Talents Growth Project(No.KY[2020]158)the 2019 Post-doctoral Junior Leader-Retaining Fellowship,la Caixa Foundation(ID100010434 and fellowship code LCF/BQ/PR19/11700011)the“Generalitat Valenciana”(SEJI/2020/034)the“Ramón y Cajal”program(J.F.-S.)support from the European Research Council under the European Union’s Horizon 2020 research and innovation programme/ERC Grant Agreement No.814804,MOF-reactors.
文摘A tetranuclear cubane-type complex[Co_(4)(ntfa)_(4)(CH_(3)O)_(4)(CH_(3)OH)_(4)](1)with a{Co_(4)O_(4)}core,and a mononuclear complex[Co(ntfa)_(2)(CH_(3)OH)_(2)](2)have been rationally obtained by adjusting the ratio of theβ-diketonate and Co(II)ions,with the synthetic processes being monitored by in situ microcalorimetry.Then,following synthetic conditions to obtain 2,but using three distinct N-donor coligands-2,2’-bipyridyl(bpy),6,6’-dimethyl-2,2’-bipyridyl(6,6-(CH_(3))_(2)-bpy)and 5,5’-dimethyl-2,2’-bipyridyl(5,5-(CH_(3))_(2)-bpy)-three novel mononuclear complexes have been obtained,[Co(ntfa)_(2)(bpy)_(2)](3),[Co(ntfa)_(2)(6,6-(CH_(3))_(2)-bpy)_(2)](4)and[Co(ntfa)_(2)(5,5-(CH_(3))_(2)-bpy)_(2)](5).The introduction of different capping coligands-as singlecrystal X-ray crystallography ascertains-fine-tunes the structures,with changes in both the distortion degree of the coordination geometry and the intermolecular interactions,which have a direct impact on the magnetic properties of these complexes.Magnetic investigations reveal field-induced single-ion magnet behavior in all complexes with distinct energy barriers(Ueff)-39.06(1),36.65(2),36.32(3),28.26(4)and 15.85 K(5).Magnetic experiments together with HF-EPR measurements and theoretical calculations demonstrate that 2 features easy-axis magnetic anisotropy(D=-60.48 cm^(-1)),whereas 3-5 show easy-plane magnetic anisotropies-D=+70.77 cm^(-1) for 3,+35.71 cm^(-1) for 4,and+51.28 cm^(-1) for 5.To our knowledge,such reversal of anisotropic nature driven by coligands is unprecedented.
