4,6-dimethoxy-1,3-phenylenebis(N-tert-butyl nitroxide) with a singlet ground state. Formal violation of a rule that m-phenylene serves as a robust ferromagnetic coupling unit

4,6-Dimethoxy-1,3-phenylenebis (N-tert-butyl nitroxide) (1) was prepared by lithiation of the corresponding dibromo compound followed by reaction with 2-methyl-2-nitrosopropane and subsequent treatment with Ag 2 O. In a frozen toluene matrix, 1 showed EPR fine structures characteristic of triplet dinitroxides: g=2.0068, D/hc=0.0179 cm -1 , and E/hc=0.0008 cm -1 . The variation in signal intensity vs reciprocal temperature deviated downward from a Curie relationship at temperatures lower than 45 K, suggesting a singlet ground states for 1