Phenanthrene-4,5-diylbis(10-methylacridinium) with a Short C+ - - C+ Contact: Preparation, Molecular Structure, Redox Properties, and Electrochromic Interconversion with Dihydropyrene Derivative
The title dication (1(2+)) was generated by oxidative bond cleavage of a 4,5-dihydoropyrene derivative (2) with two spiro(10-methylacridan) units. Despite the skewed deformation of the arylene spacer, two cationic chromophores in 1(2+) are forced to face in a proximity with a very short interatomic separation of 2.98(1) angstrom between carbenium centers (X-ray), which makes the LUMO level of 1 much lower than that of biphenyl-2,2'-diyl-type dication (3(2+)).