ESR STUDY OF HIGH-SPIN STATES DERIVED FROM TRIBENZOYLENEBENZENE

By reduction of tribenzoylenebenzene 4 with lithium in 2-methyltetrahy drofuran (MTHF) an ion pair and a cluster with S = 1 were obtained whe reas with potassium or sodium in MTHF in the presence of dicyclohexano -18-crown-6 (or a solvent of strong solvating power such as diglyme or hexamethyl-phosphoric triamide), different species with S greater tha n or equal to 1/2 were detected. The ESR spectra of the randomly orien ted pluri-anions in glassy matrix showed the existence of triplet spec ies assigned to a dianion [4(2(.-))(M+)(2)] and aggregates [4(.-)(M+)( n)4(.-)] and quartet species [4(2(.-))(M+)(3)4(.-)]. The quartet speci es was attributed to intermolecular high-spin clusters with the relati vely small zero-field splitting parameter D and vanishing E value. Fur ther reduction led to the formation of a more persistent species with a quartet ground state characterized by the zero-field parameters D = + 0.0215 cm(-1) and E = 0 cm(-1), assigned to a triradical-trianion [4 (3(.-))(M+)(3)], generated by three-electron doping per a single tribe nzoylenebenzene molecule. The observed H-1-ENDOR spectra and INDO calc ulations also confirmed the above identification. 4(3(.-)) is a stable pluri-anionic high-spin molecule in solution.