Deciphering the ground state of a C3-symmetrical Blatter-type triradical by CW and pulse EPR spectroscopy

3,3',3''-(Benzene-1,3,5-triyl)tris(1-phenyl-1H-benzo[e][1,2,4]triazin-4-yl) (1) is a C3-symmetrical triradi-cal comprised of three Blatter radical units connected at the 1, 3, 5 positions of a central trimethyleneben-zene core. This triradical has an excellent air, moisture, and thermal stability. Single-crystal XRD indicates that triradical 1 adopts a propeller-like geometry with the benzotriazinyl moieties twisted by specialIntscript and packs in 1D chains along the c axis to form an extensive network of weak intermolecular interactions. Frozen solution continuous wave (CW) EPR spectra and variable-temperature field-sweep echo-detected (FSED) spectra revealed an intramolecular ferromagnetic exchange within the spin system, supporting a quartet S = 3/2 ground state. DFT calculations further supported these experimental findings.(c) 2023 Elsevier Inc. All rights reserved.

Automated summary

Compound 1 is a C3-symmetrical triradical with excellent air, moisture, and thermal stability. It adopts a propeller-like geometry and forms 1D chains along the c axis due to weak intermolecular interactions. The intramolecular ferromagnetic exchange within the spin system supports a quartet S=3/2 ground state, as confirmed by EPR and DFT calculations.