4,5‐Bis(dimethylamino)phenanthrene and 4,5‐Bis(dimethylamino)‐9,10‐dihydrophenanthrene: Syntheses and “Proton Sponge” Properties

Abstract

Strong, almost linear N ċ H ċ N hydrogen bonds are present in 1-perchlorate and its 9,10-dihydro derivative. The N ċ N distance is even shorter and the H/CH3 bridge coupling stronger than in the analogue with a fluorene skeleton. Unprotonated 1 could be generated via a dichlorinated seven-membered dibenzosulfone.