TY - JOUR
T1 - On The Causes of Potential Inversion in 1,2,4,5-Tetrakis(amino)benzenes
AU - Adams, Christopher J.
AU - Da Costa, Rosenildo
AU - Edge, Ruth
AU - Evans, Dennis H.
AU - Hood, Michael F.
PY - 2010
Y1 - 2010
N2 - Three 3,6-difluoro-1,2,4,5-tetrakis(amino)benzene compounds, bearing dimethylamino (1), piperidin-1-yl (3), or morpholin-1-yl (5) substituents, have been synthesized and subsequently defluorinated to give the corresponding 1,2,4,5-tetrakis(amino)benzene compounds 2, 4, and 6; the crystal structures of compounds 1, 4, and 6 have been obtained. Cyclic voltammetry shows that all six compounds will lose two electrons to form dications, and the use of suitable oxidizing agents has allowed isolation and crystallographic characterization of the dications 22+ and 62+ (as [PF6]2 salts) and 42+ (as a [I5][I3] salt). The separation ΔE between the loss of the first electron and the second varies between compounds, from 0.23 V in 1 to 0.01 V in 6. Eletrochemical studies involving the use of the noncoordinating electrolyte [Bu4N][B{C6H3(CF3)2}4] show that it is possible to increase this separation, stabilizing the intermediate monocationic phase, and this has allowed the isolation and crystallographic characterization of the radical salts 2[B{C6H3(CF3)2}4] and 4[B{C6H3(CF3)2}4], the first radical cations of this family to be isolated. DFT studies of the ion pairing between oxidized forms of 1 and 2 and anions imply that the location of the ion pairing is different in the two species.
AB - Three 3,6-difluoro-1,2,4,5-tetrakis(amino)benzene compounds, bearing dimethylamino (1), piperidin-1-yl (3), or morpholin-1-yl (5) substituents, have been synthesized and subsequently defluorinated to give the corresponding 1,2,4,5-tetrakis(amino)benzene compounds 2, 4, and 6; the crystal structures of compounds 1, 4, and 6 have been obtained. Cyclic voltammetry shows that all six compounds will lose two electrons to form dications, and the use of suitable oxidizing agents has allowed isolation and crystallographic characterization of the dications 22+ and 62+ (as [PF6]2 salts) and 42+ (as a [I5][I3] salt). The separation ΔE between the loss of the first electron and the second varies between compounds, from 0.23 V in 1 to 0.01 V in 6. Eletrochemical studies involving the use of the noncoordinating electrolyte [Bu4N][B{C6H3(CF3)2}4] show that it is possible to increase this separation, stabilizing the intermediate monocationic phase, and this has allowed the isolation and crystallographic characterization of the radical salts 2[B{C6H3(CF3)2}4] and 4[B{C6H3(CF3)2}4], the first radical cations of this family to be isolated. DFT studies of the ion pairing between oxidized forms of 1 and 2 and anions imply that the location of the ion pairing is different in the two species.
U2 - 10.1021/jo902411b
DO - 10.1021/jo902411b
M3 - Article
SN - 1520-6904
VL - 75
SP - 1168
EP - 1178
JO - Journal of Organic Chemistry
JF - Journal of Organic Chemistry
IS - 4
ER -