The Structure and Magnetic Properties of the Two-Dimensional Di-Pyrazine Bridged Polymers M(pz)2Br2 (M = FeII, CoII, NiII)

Abstract

The polymeric compounds M(pyrazine)2Br2 [M = Fe (1), Co (2), and Ni (3)] have been synthesized by the addition of a solution of pyrazine in methanol to a methanolic solution of the anhydrous metal bromide. The crystal structures of (1)-(3) were determined using powder synchrotron and neutron diffraction data and were found to be isostructural. The structures consist of pseudo-octahedral units, doubly linked by pyrazine ligands to form two-dimensional sheets. Magnetic susceptibility data were recorded for each complex down to 5 K and reveal paramagnetic behaviour at high temperatures and antiferromagnetic interactions at low temperatures. Comparison of the structures and magnetism of these and other M(pz)2X2 compounds highlight the relative importance of the canting of the pyrazine ligands on the strength of the magnetic exchange.

Magnetism in a family of $S = 1$ square lattice antiferromagnets Ni$X_2$(pyz)$_2$ ($X = $ Cl, Br, I, NCS; pyz = pyrazine)

“…33 A related Ni(II) compound, 4, reportedly exists in two polymorphic forms, however, as will be described below, we find only one of the two structures present in our samples. 34,35 As for the magnetic properties of 1-4, the temperature dependence of the magnetic susceptibility data, χ(T ), for 1 and 2 have been reported (T ≥ 5 K) 32,33 while those for 3 and 4 have not. The analysis of the χ(T ) data for 1 and 2 gave D = 7.92 and 14.8 K, respectively.…”

Frustration-free spatially anisotropic S=1 square-lattice antiferromagnet Ni[SC(NH2)2Zhao1, Zhao2, Chen3 et al. 2019Phys. Rev. B4110View full textAdd to dashboardCite

“…With increasing J 2 , a stripe order is introduced. As far as we know, few S = 1 square lattice antiferromagnets have been discovered [18,19].…”

Antiferromagnetism in a Family of S = 1 Square Lattice Coordination Polymers NiX2(pyz)2 (X = Cl, Br, I, NCS; pyz = Pyrazine)

“…More recently, the structure of 2 was determined by powder neutron diffraction and found to be consistent with the hypothetical square lattice structure. 33 A related Ni(II) compound, 4, reportedly exists in two polymorphic forms, however, as will be described below, we find only one of the two structures present in our samples. 34,35 As for the magnetic properties of 1-4, the temperature dependence of the magnetic susceptibility data, χ(T ), for 1 and 2 have been reported (T ≥ 5 K) 32,33 while those for 3 and 4 have not.…”

“…The data were fitted to an anisotropic 2D model which gave D = 7.92 and 14.8 K, zJ = 0.39 and 0.95 K (z = 4), g = 2.17 and 2.31 for 1 and 2, respectively. 32,33 Having discussed the magnetic dimensionality and the single-spin anisotropy from the aforementioned measurements, we now remeasure/analyze the DC susceptibility data for 1 and 2 [see Fig. 12(a) and (b)].…”