Triangle, square and delta-chain based cobalt tetrazolate magnets

Abstract

Three novel tetrazole-based frustrated magnets, namely, Co3(OH)2(3-ptz)2(SO4)(H2O)4 (1), Co2(OH)(tzba)(H2O)4 (2) and [Co(OH)(tta)] (3) (3-ptz = 5-(3-pyridyl) tetrazole, H2tzba = 4-(1H-tetrazol-5-yl) benzoic acid, Htta = 1H-tetrazole) were hydrothermal synthesized and magnetically characterized. Compound 1 is a 2D (4,4) layered structure assembled by sulfate capped triangular [Co3(μ3-OH)(μ3-SO4)] clusters and in situ synthesized μ3-3-ptz ligands. Compound 2 features Co3(μ3-OH) triangle based magnetic Δ-chains linked with in situ generated μ5-tzba ligands to form a 2D layer. Compound 3 is a uninodal eight-connected body-centered-cubic (bcu) 3D network with square Co4O4 clusters as nodes and μ4-tta ligands as linkers. Interestingly, spin frustration was observed in these complexes due to inherent spin competition in triangle, Δ-chain and square. Magnetic studies show that 1 behaves as antiferromagnet, while 2 and 3 exhibits spin canting and long-range magnetic ordering.

Sodium Transition Metal Vanadates from Hydrothermal Brines: Synthesis and Characterization of NaMn4(VO4)3, Na2Mn3(VO4)3, and Na2Co3(VO4)2(OH)2

“…The cobalt oxide layer in 3 is comprised of a hexagonal arrangement of Co–O bonds coordinated to the four nearest hexagons on the top and bottom by a parallelogram of Co–O. An idealized Kagome layer can also be viewed as a series of edge shared delta chains, , of metal‐oxygen octahedra. This arrangement also produces hexagon shapes within the layer.…”

New High-Nuclear Coordination Complexes Constructed by 2-Hydroxymethylpyridine: From Antiferromagnetic to Spin Glass and Ferromagnetic Behavior

“…At 300 K, the χ m T value is equal to 27.96 cm 3 K mol –1 for 5 , which is much higher than the expected value for nine spin-only Co II cations (16.875 cm 3 K mol –1 , g = 2.00) because of the strong orbital contributions of the octahedral Co II ions. The χ m T value gradually reduced as the temperature was lowered until it reached a minimum value of 10.00 cm 3 K mol –1 at 7 K and then increased rapidly to reach a sharp maximum value of 14.69 cm 3 K mol –1 at 4.5 K. The nature of the χ m T vs T plot above 4.5 K indicates the presence of ferrimagnetic-type behavior resulting from the different intermolecular interactions compared with those observed in 4 (see discussed above). − Finally, the χ m T value dropped to 8.18 cm 3 K mol –1 at 2 K, which is probably caused by zero-field splitting and saturation effects. − …”

Synthesis, structure, magnetic and biological activity studies of bis-hydrazone derived Cu(ii) and Co(ii) coordination compounds

“…The plot shows that disappearance of the peak above 0.06 T. These observance gives a clear indication of antiferromagnetic ordering at low temperature most likely due to field induced polarization. [31][32][33] Zero field cooled (ZFC) and field cooled (FC) magnetic measurements were performed at 0.1 T and a nice bifurcation was observed at the temperature of 3.5 K (inset, Fig. 8).…”