posted on 2022-10-05, 17:03authored byPetra Stanić, Dario Barišić, Damir Pajić, Ana Šantić, Krešimir Molčanov
A series of six novel salts of 5,6-dichloro-2,3-dicyanosemiquinone
(DDQ) radical anions with aromatic cations is studied by structural
characterization, magnetization, and conductivity measurements. Different
types of stacking of DDQ radicals, which determine electrical and
magnetic properties, are observed: regular stacks of equidistant radicals
(resulting in semiconductivity along the direction of stacking), stacks
of pancake-bonded dimers, isolated pancake-bonded dimers, and mixed
stacks comprising DDQ radicals and aromatic cations. General features
of pancake bonding of DDQ radicals are defined: parallel ring planes,
offset along the carbonyl···carbonyl axis by 2.05–2.15
Å, and interplanar separations of 2.90–2.95 Å (for
pancake-bonded dimers) or 3.08–3.24 Å (for regular stacks
of equidistant radicals).