A Stable Aluminum Tris(dithiolene) Triradical
Phuong M. Tran, Yuzhong Wang, Boris Dzikovski, Mitchell E. Lahm, Yaoming Xie, Pingrong Wei, Vladislav V. Klepov, Henry F. Schaefer, Gregory H. Robinson
Abstract
High Resolution Image Download MS PowerPoint Slide 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 DQ = 0.18 kcal mol –1 (SQUID); Δ E DQ = 0.14 kcal mol –1 (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 .