posted on 2025-02-05, 01:32authored byAbhishek
R Nath, Manish Kumar, Md. Ehesan Ali
Organic diradical dications, due
to reduced intermolecular interactions,
exhibit a greater tendency to adopt high spin states in the solid
phase compared to their neutral diradical counterparts. This characteristic
makes them promising candidates for applications involving organic
electronics. We present a theoretical study of a recently synthesized
sulfur-based diradical dication, a unique system exhibiting a robust
triplet ground state. Using a number of density functional theory
(DFT)-based methods (e.g., standard broken-symmetry DFT, constrained
DFT, spin-flip TDDFT) and wave function-based multireference CASSCF+NEVPT2
methods, we investigate its magnetic properties and explore the influence
of chalcogen substitution on magnetic exchange coupling. An active
space scanning method was adopted to overcome the difficulties in
choosing the correct active space for multireference calculation.
Our findings highlight the critical role of multireference methods
in accurately capturing the magnetic behavior of highly π-conjugated
systems. The study reveals a surprising variation in magnetic properties
among sulfur, selenium, and tellurium-based diradical dications despite
being elements of the same group. These results offer valuable insights
into the design and tuning of magnetic properties in organic diradical
dications.