Pohle, M.H.; Böhme, M.; Lohmiller, T.; Ziegenbalg, S.; Blechschmidt, L.; Görls, H.; Schnegg, A.; Plass, W.: Magnetic Anisotropy and Relaxation of Pseudotetrahedral [N2O2] Bis-Chelate Cobalt(II) Single-Ion Magnets Controlled by Dihedral Twist Through Solvomorphism. Chemistry - A European Journal 29 (2023), p. e202202966/1-7
10.1002/chem.202202966
Open Access Version
Abstract:
The methanol solvomorph 1 ⋅ 2MeOH of the cobalt(II) complex [Co(LSal,2−Ph)2] (1) with the sterically demanding Schiff-base ligand 2-(([1,1′-biphenyl]-2-ylimino)methyl)phenol (HLSal,2−Ph) shows the thus far largest dihedral twist distortion between the two chelate planes compared to an ideal pseudotetrahedral arrangement. The cobalt(II) ion in 1 ⋅ 2MeOH exhibits an easy-axis anisotropy leading to a spin-reversal barrier of 55.3 cm−1, which corresponds to an increase of about 17 % induced by the larger dihedral twist compared to the solvent-free complex 1. The magnetic relaxation for 1 ⋅ 2MeOH is significantly slower compared to 1. An in-depth frequency-domain Fourier-transform (FD-FT) THz-EPR study not only allowed the direct measurement of the magnetic transition between the two lowest Kramers doublets for the cobalt(II) complexes, but also revealed the presence of spin-phonon coupling. Interestingly, a similar dihedral twist correlation is also observed for a second pair of cobalt(II)-based solvomorphs, which could be benchmarked by FD-FT THz-EPR.