| Institution: | 1. Department of Molecular Science and Engineering, National Taipei University of Technology, Taipei, Taiwan
National Synchrotron Radiation Research Center, Hsinchu, Taiwan;2. Department of Molecular Science and Engineering, National Taipei University of Technology, Taipei, Taiwan;3. National Synchrotron Radiation Research Center, Hsinchu, Taiwan;4. Department of Physics, Graduate School of Science, Osaka Metropolitan University, Sakai, Osaka, Japan;5. Institute of Chemistry, Academia Sinica, Taipei, Taiwan;6. Department of Materials Engineering Science, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka, Japan |
| Abstract: | Two cobalt(II) halide complexes with 1,2,4-triazole as a ligand were synthesized. Their structures were determined by extended x-ray absorption fine structure (EXAFS) and powder x-ray diffraction (XRD). Both complexes Co(Htrz)Cl2]n ( 1 ) and {Co(Htrz)2(trz)]BF4}n ( 2 ) form one-dimensional polymeric chain and the distances of Co?Co are 3.3521(2) Å and 3.8629(2) Å, respectively. The Htrz and Cl? are bridging ligands to connect two Co(II) ions in 1 , and the local environment of Co site is in a distorted octahedron with {CoN2Cl4} core. In complex 2 , two Htrz and one trz are bridging ligands to connect two Co(II) ions, and the local geometry of Co is in a pseudo octahedron with {CoN6} core. The analysis of Co LII,III-edge XAS indicates that the Co(II) of both complexes are at high spin state with t2g5eg2 configuration and the crystal field strength (10Dq) is about 1.2 eV. The broken-symmetry DFT calculations indicate that antiferromagnetic coupling state of Co?Co is the most stable state in both complexes; and the coupling constants of 1 and 2 are ?0.32 cm?1 and ?3.70 cm?1, respectively. Based on the distances of Co?Co and coupling constants, such antiferromagnetic interaction is achieved through triazole ligands. |
