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+)).
Intramolecular Methylacridan-Methylacridinium Complexes with a Phenanthrene-4,5-diyl or Related Skeleton: Geometry-Property Relationships in Isolable CH Bridged Carbocations
Bridging the gap: Snapshots of 1,6‐H‐shift precursors indicate that a narrower CH⋅⋅⋅C+ separation (D in the ORTEP diagram) in the title complexes induces faster degenerate rearrangement of 1+. A contact distance of less than 2.7 Å is necessary to realize the organic three‐center two‐electron bond of [CHC]+, as indicated by extrapolation of the X‐ray data.