A Stable Aluminum Tris(dithiolene) Triradical.

Authors :: Tran PM
Wang Y
Dzikovski B
Lahm ME
Xie Y
Wei P
Klepov VV
Schaefer HF 3rd
Robinson GH
Source :: Journal of the American Chemical Society [J Am Chem Soc] 2024 Jun 12; Vol. 146 (23), pp. 16340-16347. Date of Electronic Publication: 2024 May 31.
Publication Year :: 2024
Abstract: A stable aluminum tris(dithiolene) triradical ( 3 ) was experimentally realized through a low-temperature reaction of the sterically demanding lithium dithiolene radical ( 2 ) with aluminum iodide. Compound 3 was characterized by single-crystal X-ray diffraction, UV-vis and EPR spectroscopy, SQUID magnetometry, and theoretical computations. The quartet ground state of triradical 3 has been unambiguously confirmed by variable-temperature continuous wave EPR experiments and SQUID magnetometry. Both SQUID magnetometry and broken-symmetry DFT computations reveal a small doublet-quartet energy gap [Δ E <subscript>DQ</subscript> = 0.18 kcal mol <superscript>-1</superscript> (SQUID); Δ E <subscript>DQ</subscript> = 0.14 kcal mol <superscript>-1</superscript> (DFT)]. The pulsed EPR experiment (electron spin echo envelop modulation) provides further evidence for the interaction of these dithiolene-based radicals with the central aluminum nucleus of 3 .