Stable Hydrocarbon Diradical, An Analogue of Trimethylenemethane

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作者：

A Rajca，K Shiraishi，M Vale，H Han，S Rajca

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摘要：

Hydrocarbon diradical 1, a new stable, 3-fold symmetric analogue of trimethylenemethane (TMM) with no heteroatom perturbation, is prepared and studied. Such diradicals should provide new building blocks for high-spin hydrocarbon polyradicals with very strong net ferromagnetic coupling. Magnetic studies (SQUID) and EPR spectroscopy indicate that 1 in tetrahydrofuran-d8 (THF-d8) possesses a triplet (S = 1) ground state, with strong ferromagnetic coupling. After annealing at room temperature, the EPR spectra of 1 (approximately 0.02 M in frozen THF-d8) consist of a single narrow resonance (deltaH(pp) < 1 G), and intermolecular antiferromagnetic coupling is increased by 1 order of magnitude. This behavior is consistent with the presence of exchange narrowing, thus suggesting aggregation of 1 in THF-d8. Blue solutions of 1 in THF-d8 possess a strong UV-vis absorption band at lambda(max) approximately 640 nm. Diradical 1 in THF-d8 is stable (or persistent) at room temperature, with no detectable decomposition for at least 2 days.

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关键词：

SPIN ORGANIC-MOLECULES MACROCYCLIC POLYARYLMETHYL POLYRADICALS TRIMETHYLENEMETHANE NEGATIVE-ION ELECTRONIC-STRUCTURE GROUND-STATES PHOTOELECTRON-SPECTROSCOPY MAGNETIC-PROPERTIES COUPLING UNITS TRIPLET CHEMISTRY