Diverse structures and magnetism of cobalt(II) and manganese(II) compounds with mixed azido and carboxylato bridges induced by methylpyridinium carboxylates |
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Authors: | Jia Qin-Xiang Tian Hua Zhang Jian-Yong Gao En-Qing |
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Institution: | Shanghai Key Laboratory of Green Chemistry and Chemical Processes, Department of Chemistry, East China Normal University, Shanghai, PR China. |
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Abstract: | Herein we present a systematic study of the structures and magnetic properties of six coordination compounds with mixed azide and zwitterionic carboxylate ligands, M(N3)2(2‐mpc)] (2‐mpc=N‐methylpyridinium‐2‐carboxylate; M=Co for 1 and Mn for 2 ), M(N3)2(4‐mpc)] (4‐mpc=N‐methylpyridinium‐4‐carboxylate; M=Co for 3 and Mn for 4 ), Co3(N3)6(3‐mpc)2(CH3OH)2] ( 5 ), and Mn3(N3)6(3‐mpc)2] ( 6 ; 3‐mpc=N‐methylpyridinium‐3‐carboxylate). Compounds 1 – 3 consist of one‐dimensional uniform chains with (μ‐EO‐N3)2(μ‐COO) triple bridges (EO=end‐on); 5 is also a chain compound but with alternating (μ‐EO‐N3)2(μ‐COO)] triple and (EO‐N3)2] double bridges; Compound 4 contains two‐dimensional layers with alternating (μ‐EO‐N3)2(μ‐COO)] triple, (μ‐EO‐N3)(μ‐COO)] double, and (EE‐N3) single bridges (EE=end‐to‐end); 6 is a layer compound in which chains similar to those in 5 are cross‐linked by a μ3‐1,1,3‐N3 azido group. Magnetically, the three CoII compounds ( 1 , 3 , and 5 ) all exhibit intrachain ferromagnetic interactions but show distinct bulk properties: 1 displays relaxation dynamics at very low temperature, 3 is an antiferromagnet with field‐induced metamagnetism due to weak antiferromagnetic interchain interactions, and 5 behaves as a noninnocent single‐chain magnet influenced by weak antiferromagnetic interchain interactions. The magnetic differences can be related to the interchain interactions through π–π stacking influenced by different substitution positions in the ligands and/or different magnitudes of intrachain coupling. All of the MnII compounds show overall intrachain/intralayer antiferromagnetic interactions. Compound 2 shows the usual one‐dimensional antiferromagnetism, whereas 4 and 6 exhibit different weak ferromagnetism due to spin canting below 13.8 and 4.6 K, respectively. |
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Keywords: | carboxylate ligands cobalt magnetic properties manganese N ligands |
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