syn-8,16-Dimethylphenanthro[9,10:1',2'][2.2]methacyclophane-1,9-diene: the first derivative of 8,16-dimethyl[2.2]methacyclophanediene failing to undergo spontaneous valence isomerization to the dihydropyrene system
syn-8,16-Dimethylphenanthro[9,10:1',2'][2.2]methacyclophane-1,9-diene: the first derivative of 8,16-dimethyl[2.2]methacyclophanediene failing to undergo spontaneous valence isomerization to the dihydropyrene system
syn-8,16-Dimethylphenanthro[9,10:1',2'][2.2]methacyclophane-1,9-diene: the first derivative of 8,16-dimethyl[2.2]methacyclophanediene failing to undergo spontaneous valence isomerization to the dihydropyrene system