# Measurement and Analysis of Vibronic Coupling in Two Dysprosium(III) Complexes of Opposite Magnetic Anisotropy

## TL;DR

This paper studies how molecular vibrations affect magnetic properties in dysprosium complexes using advanced spectroscopy techniques.

## Contribution

The study provides direct experimental evidence of vibronic coupling effects in dysprosium complexes with opposite magnetic anisotropy.

## Key findings

- A prominent spectral feature at 340 cm−1 was observed, corresponding to electronic excitation.
- The vibronic coupling effect is shown to depend on the direction of the external magnetic field.
- FIRMS is validated as a powerful tool for studying magnetic anisotropy and vibronic coupling.

## Abstract

The loss of magnetic memory in single‐molecule magnets (SMMs) is caused by the coupling of molecular vibrations to spin states, which plays a significant role in magnetic relaxation processes. Gaining direct evidence of vibronic coupling using experimental techniques is critical to understanding and controlling this phenomenon. Most studies focus on assessing the spin‐phonon coupling in SMMs to help control this relaxation; herein we gain insight by comparing the SMM [Dy(OPCy3)2(H2O)5][CF3SO3]3.2(OPCy3) to the non‐SMM [Dy{N(SiMe3)2}3] through collection of far‐infrared magnetospectroscopy (FIRMS) spectra and validation with ab initio calculations. Single‐crystal measurements display a prominent feature in the spectra at 340 cm−1, corresponding to an electronic excitation which varies depending on the direction of external magnetic field applied. These findings demonstrate the complicated effect of magnetic anisotropy on the vibronic coupling in SMMs and demonstrate the power of FIRMS to study these effects.

Single‐crystal far‐infrared magnetospectroscopy is used to reveal magnetic anisotropy and vibronic coupling in a pair of dysprosium(III) complexes.