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Line Shape Analysis of Dynamic NMR Spectra for Characterizing Coordination Sphere Rearrangements at a Chiral Rhenium Polyhydride Complex
Published on: July 27, 2022
Coordination polymers with end-on azido and pyridine carboxylate N-oxide bridges displaying long-range magnetic
Zheng He1, Zhe-Ming Wang, Song Gao
1Beijing National Laboratory for Molecular Sciences, State Key Lab of Rare Earth Materials Chemistry and Applications and PKU-HKU Joint Lab on Rare Earth Materials and Bioinorganic Chemistry, Peking University, Beijing 100871, China.
Abstract:
A series of 2D and one 3D transition-metal-azido coordination polymers with pyridine carboxylate N-oxide, isonicotinate N-oxide (INO), and nicotinate N-oxide (NNO) as the coligands were synthesized by a hydrothermal method and structurally and magnetically characterized. These complexes have the formulas [M(L)(N3)(H2O)]n (L = INO and M = Mn, 1.Mn; Co, 2.Co; Ni, 3.Ni and L = NNO and M = Mn, 4.Mn; Co, 5.Co; Ni, 6.Ni) and [Cu(L)(N3)(H2O)(0.5)]n (L = INO, 7.Cu; NNO, 8.Cu). All complexes consist of end-on azido and syn-syn carboxylato mixed-bridged M-N(3)/COO chains that are further linked by the pyridine N-oxide group of the INO or NNO to give rise to 2D layered structures for 1.Mn, 2.Co, 3.Ni, 4.Mn, 5.Co, 6.Ni, and 8.Cu and a 3D framework for 7.Cu. The high-temperature magnetic susceptibilities are dominated by low-dimensional behavior while long-range ordering sets in at low temperatures. The Mn complexes are antiferromagnets, and the others are metamagnets. In addition, 5.Co exhibits slow magnetic relaxation behavior at low temperatures. The metamagnetism in each case is due to strong intrachain ferromagnetic interactions and weak interchain antiferromagnetic ones.
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