Largely Enhancing the Blocking Energy Barrier and Temperature of a Linear Cobalt(II) Complex through the Structural Distortion: A Theoretical Exploration.

Abstract

Complete-active-space self-consistent field and N-electron valence second-order perturbation theory have both been employed to investigate the magnetic anisotropy of one two-coordinate cobalt(II) compound via altering the Co-C bond lengths and twist angle φ. The calculated energy barrier Ueff decreases with the decrease in the Co-C bond lengths due to the gradually increasing interaction between the 3d orbitals of CoII and the coordination ligand field and then to the decrease in the ground orbital angular moment L of CoII. Thus, we cannot improve Ueff simply by shortening the Co-C bond lengths. However, by rotating the twist angle φ from 60 to 0°, it is surprising to find that the energy barrier and blocking temperature can be enhanced up to 1559.1 cm-1 and 90 K, respectively, with φ = 0°, which are prominent even among lanthanide-based single-molecule magnets.