Synergy of Experiment and Broadened Exploration of Ab Initio Calculations for Understanding of Lanthanide–Pentacyanidocobaltate Molecular Nanomagnets and Their Optical Properties

We present a synergistic experimental–theoretical
methodology
for the investigation of lanthanide-based single-molecule magnets
(SMMs), demonstrated using the example of novel heterometallic molecules
incorporating Nd3+/Ce3+ ions combined with three
different, rarely explored, penta­cyanidocobaltate(III) metalloligands,
[CoIII(CN)5(azido/nitrito-N/iodido)]3–. The theoretical part of our approach
broadens the exploration of ab initio calculations
for lanthanide(III) complexes toward the convenient simulations of
such physical characteristics as directional dependences of Helmholtz
energy, magnetization, susceptibility, and their thermal and field
evolution, as well as light absorption and emission bands. This work
was conducted using newly designed SlothPy software (https://slothpy.org). It is introduced
as an open-source Python library for simulating various physical properties
from first-principles based on results of electronic structure calculations
obtained within popular quantum chemistry packages. The computational
results were confronted with spectroscopic and ac/dc-magnetic data, the latter analyzed using previously
designed relACs software. The combination of experimental and computational
methods gave insight into phonon-assisted magnetic relaxation mechanisms,
disentangling them from the temperature-independent quantum tunneling
of magnetization and emphasizing the role of local-mode processes.
This study provides an understanding of the changes in lanthanide(III)
magnetic anisotropy introduced with penta­cyanidocobaltates(III)
modifications, theoretically exploring also potential applications
of reported compounds as anisotropy switches or optical thermometers.