Electronic structure of zwitterionic diamino-meta-quinonoid molecules: identity of UV absorption bands

Dipole driven bonding schemes of quinonoid zwitterions on surfaces

“…1). [7][8][9][10] The molecules, although electrically neutral as a whole, carry positive and negative charges on opposite parts of the C 6 ring 'core', resulting in a large dipole moment of approximately 10 Debye (D). 11 We focus our study on p-benzoquinonemonoimine zwitterion 1, where R = H, also referred to as the ''parent'' zwitterion, but also test the somewhat larger N,N 0 -diethyl derivative 2 where R = C 2 H 5 .…”

Contrasting behaviour of TCNE and TCNQ zwitterionic benzoquinonemonoimine derivatives and coordination of a tricyanoethenyl substituent to Pd(0)

“…When the reaction of 1a with TCNQ was carried out in the presence of NEt 3 , 5 was formed as the main product, either by a deprotonation of first formed 3a [see eqn (2)] or because proton migration in 7 has been prevented. This reaction also yielded new 8 in 15% yield [eqn (4)]. Although single crystals of 8 suitable for Xray diffraction could not be obtained, all spectroscopic data point to the formation of 8.…”

Regioselective addition of DDQ on a quinoid ring: an entry into chiral zwitterionic bridging ligands

“…220, 340 and 350 nm that were previously attributed to π  π* transitions of the zwitterionic part ( Figure 6). 17 On the other hand, the fourth band at ca. 270 nm could be due to the reduced DDQ moiety.…”