Triimidosulfonates as Acute Bite‐Angle Chelates: Slow Relaxation of the Magnetization in Zero Field and Hysteresis Loop of a Co^II Complex

Abstract

Starting from a polyimido sulfonate the four-coordinate, N,N'-chelated Co(II) complex [Co{(NtBu)3 SMe}2 ] (1) was synthesized, and its molecular structure was elucidated by single-crystal X-ray structural analysis. The acute N-Co-N bite angle imposed by the N,N'-chelating ligand (NtBu)3 SMe(-) leads to pronounced C2v distortion of the tetrahedral coordination environment and thus to high anisotropy of the Co(II) ion (D≈-58 cm(-1) ), favorable for single-molecule-magnet (SMM) properties. Magnetic measurements revealed a high barrier to spin reversal (Ueff =75 cm(-1) ) that gives rise to the observation of slow relaxation of the magnetization in zero field and a hysteresis loop at 2 K for this unique complex.

Trigonal antiprismatic Co(ii) single molecule magnets with large uniaxial anisotropies: importance of Raman and tunneling mechanisms

“…82 In other cases the data have been fit only with a Raman term when the energy barrier did not match the energy difference between states. 26,34,83–86 In another system, the dependence of τ was fit with Orbach, Raman and direct terms although in one of these cases the Raman term was found to be zero. 87 while in the other the direct was zero.…”

Magnetic anisotropy of a CoII single ion magnet with distorted trigonal prismatic coordination: theory and experiment

“…Similar behaviour has been observed for other complexes. 39,40 However, since the temperature-dependent curves also did not improve upon adding a direct term proportional to T, we removed the term AH m T altogether from the relaxation expressions. The temperature dependent data was thus fitted using:…”

An iron ketimide single-molecule magnet [Fe4(NCPh2)6] with suppressed through-barrier relaxation

“…1,2 However, it is oen the case that molecules with large U nevertheless do not show long lifetimes or signicant zero-eld magnetic hysteresis. 1,[3][4][5][6][7][8][9][10] In these cases, through-barrier relaxation mechanisms (i.e., quantum tunnelling or Raman relaxation) are typically to blame.…”