PREPARATIONS AND SPIN-SPIN INTERACTIONS OF 4,4'-(TRIPTYCENE-1,8-DIYL)BIS(1-METHYL-2,6-DIPHENYLPYRIDINYL) DIRADICAL AND ITS 1,5-DIYL ISOMER

4,4′-(Triptycene-1,8-diyl)bis(1-methyl-2,6-diphenylpyridinyl)diradical was prepared by 3%-Na-Hg reduction of the corresponding dication and the ground state was estimated to be triplet or singlet with small S-T energy gap (< 20 J mol−1). No triplet signal was observed under the similar conditions for the corresponding 1,5-diyl derivative.