Herein, we report a new trigonal prismatic cobalt(II) complex that behaves as a single molecule magnet. The obtained zero‐field splitting, which is also directly accessed by THz‐EPR spectroscopy (−102.5 cm−1), results in a large magnetization reversal barrier U of 205 cm−1. Its effective value, however, is much lower (101 cm−1), even though there is practically no contribution from quantum tunneling to magnetization relaxation.

Two series of Er and Yb thiocyanates were studied as SMMs. Some empirical patterns for further development of Er and Yb based SMMs were proposed. The Δeff value for Yb aquathiocyanate is among the highest known for molecular complexes of this Ln.

Here we report two new ligands from a 2,6-bis-(pyrazol-3-yl)pyridine family often used in spin-crossover research and their iron(II) and cobalt(II) complexes with the metal ion trapped in the high-spin state in solids (according to magnetometry and X-ray diffraction data). The iron(II) complexes, however, show a gradual spin-crossover in acetonitrile solution, [a] A.N.

A series of new Co II -Ln III complexes with polynuclear {Co 2 Ln(NO 3 )(Piv) 6 } (Ln = La, Gd, Dy; Piv = pivalate) cores were prepared by self-assembly reactions or step-by-step assembly.[Co 2 Dy(NO 3 )(Piv) 6 (MeCN) 2 ] was used as the starting compound for the synthesis of the trinuclear analogue [Co 2 Dy(NO 3 )(Piv) 6 -(py) 2 ] (py = pyridine) and the pentanuclear complex [{Co 2 Dy-(NO 3 )(Piv) 6 }{CoL(Piv)(H 2 O)} 2 ][NO 3 ] 2 [L = 2,6-bis(2-pyridyl)-4-(4pyridyl)pyridine]. The effects of the coordination environment and temperature on the distortion of the Ln III coordination polyhedra were analyzed for a series of coordination compounds with M II 2 Ln III cores and close analogues. The distortion of the Ln III polyhedron depends on both the composition of [a] N.