ECAMP 15

First experimental observations and theoretical insights into rotational and vibrational magnetism in molecules date back more than 50 years, but a comprehensive framework for vibrationally induced magnetism remains elusive. Analogous to magnetic effects induced by molecular rotation, twofold degenerate molecular vibrations, when excited with a π/2 phase shift, induce rotational motions of the nuclei, generating vibrational magnetic moments and intramolecular magnetic fields. We derive a consistent theoretical framework for these effective couplings, unifying nuclear spin-vibration and nuclear spin-rotation coupling. Calculations on benchmark molecules, which are known to show a vibrational Zeeman effect, demonstrate non-negligible vibrationally induced chemical shifts, and therefore a non-trivial intermolecular field geometry. Given the growing interest in molecular magnetism, particularly based on transition-metal complexes, we focus on metal phthalocyanines — a versatile, planar, macrocyclic molecules with a central metal ion — to identify configurations that maximize vibrationally induced magnetic effects.