jo401921f_si_003.cif (106.76 kB)
Oxidation Products of Doubly Trimethylene-Bridged Tetrabenzyl p‑Phenylenediamine Paracyclophane
dataset
posted on 2013-11-15, 00:00 authored by Almaz S. Jalilov, Lu Han, Stephen F. Nelsen, Ilia A. GuzeiWe report synthesis and investigation
of doubly trimethylene-bridged
tetrabenzyl-p-phenylenediamine 1(Bz) in its singly and doubly charged redox states. The singly oxidized
monoradical cation, which is a mixed-valence (MV) system with directly
interacting charge-bearing units, shows broad and solvent-sensitive
intervalence bands consistent with class II compounds according to
the Robin–Day classification. The doubly oxidized diradical
dication of 1(Bz) exists in the spin-paired singlet state
with thermally accessible triplet state. It has similar conformations
as the other dimeric p-phenylenediamines, such as
derivatives 1(Me) and 1(Et), in both the
solid-state and solution phases. The successful isolation of the single-crystalline 1(Bz)2+ diradical dications with two
different in nature counteranions, relatively highly coordinating
SbF6– and weakly coordinating carborane
[undecamethylcarborane HCB11Me11– (CB–)], reveals the distinct effect of the nature
of counterions on the structural features of diradical dication. Cyclic
voltammetry measurements of 1(Bz) in dichloromethane
reveal separation of the first and second oxidation potential by 0.12
V (2.8 kcal/mol), indicating relatively stable mixed-valence state
in the dichloromethane, whereas in the acetonitrile both the first
and second oxidation potentials overlap into one unresolved redox
peak with minimal separation.