Slow Magnetic Relaxation in One-Dimensional Azido-Bridged Co II Complexes
Crystal structures and magnetic properties of three one-dimensional (1D) azido-bridged cobalt(II) chains with different amide ligands (L), [Co (N ) (DMF) ] (1), [Co (N ) (DEF) ] (2), and [Co (N ) (DIPF) ] (3) (DMF = N,N-dimethylformamide, DEF = N,N-diethylformamide, and DIPF = N,N-diisopropylformami...
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Published in | Inorganic chemistry Vol. 56; no. 14; pp. 8058 - 8067 |
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Main Authors | , , , , , , |
Format | Journal Article |
Language | English |
Published |
United States
17.07.2017
|
Online Access | Get full text |
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Summary: | Crystal structures and magnetic properties of three one-dimensional (1D) azido-bridged cobalt(II) chains with different amide ligands (L), [Co
(N
)
(DMF)
] (1), [Co
(N
)
(DEF)
] (2), and [Co
(N
)
(DIPF)
] (3) (DMF = N,N-dimethylformamide, DEF = N,N-diethylformamide, and DIPF = N,N-diisopropylformamide), are reported to investigate the influence of L on their structures and magnetic properties. Single-crystal X-ray crystallographic analysis revealed that, although 1-3 all consist of cobalt chains bridged by end-on (EO) azides, the coordination geometry of the Co
ions and the repeating units of the 1D structures are quite different. As the size of L increases, the ratio of L to Co
decreases from 6:4 in 1 to 5:4 and 4:4 in 2 and 3, respectively. In 1, two [CoN
O
] and two [CoN
O
] distorted octahedra form the {[CoN
O
][CoN
O
]
[CoN
O
]} tetramers (denoted as Co
A), which are linked to each other by sharing the N-N edge to form the chain. Similarly, the chain structure of 3 is constructed from a similar tetramer unit {[CoN
][CoN
O
]
[CoN
]} (denoted as Co
B), where half of the Co
centers are in the [CoN
] trigonal bipyramid because of the larger steric effect of the DIPF ligand, while, for compound 2 of the medium-sized amide, it has the transition structure between those of 1 and 3. The chain is composed of two different repeating units: Co
A unit similar to that in 1 and Co
B unit similar to that in 3. Because of their similar structures, compounds 1-3 exhibit analogical magnetic properties. Direct-current magnetic measurements demonstrated that all compounds show intrachain ferromagnetic coupling through the EO azides and interchain anti-ferromagnetic interactions. Alternating-current data revealed the slow magnetic relaxation in the anti-ferromagnetic ordered phases. While compound 1 exhibits spin glass behavior, compounds 2 and 3 behave as the single-chain magnets. This difference might come from the interference of the anti-ferromagnetic ordering on the magnetic dynamic of the magnetic chain. |
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ISSN: | 0020-1669 1520-510X |
DOI: | 10.1021/acs.inorgchem.7b00736 |