Charge-transfer complexes of 4-methylpiperidine with σ- and π-acceptors

The solid charge-transfer (CT) molecular complexes formed in the reaction of the electron donor 4-methylpiperidine (4MP) with the σ-electron acceptor iodine and π-acceptors 7,7,8,8-tetracyanoquinodimethane (TCNQ), 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) and 2,4,4,6-tetrabromo-2,5-cyclohexadienone (TBCHD) have been investigated spectrophotometrically in chloroform at 25 °C. These were characterized through electronic and infrared spectra as well as elemental and thermal analysis. The obtained results showed that the formed solid CT-complexes have the formulas [(4MP) I](+)I(-)3, [(4MP)(DDQ)2] and [(4MP)(TBCHD)] and with TCNQ the adduct [TCMPQDM] is obtained through N-substitution reaction in full agreement with the known reaction stoichiometries in solution as well as the elemental measurements. The formation constant KCT, molar extinction coefficient εCT, free energy change ΔG(0), CT energy ECT and the ionization potential Ip have been calculated for the CT-complexes [(4MP) I](+)I(-)3, [(4MP)(DDQ)2] and [(4MP)(TBCHD)].

Spectrophotometric and thermal studies on the charge--transfer complexes of 4-(aminomethyl) piperidine as donor with σ- and π-electron acceptors

The spectroscopic characteristics of the solid charge-transfer molecular complexes (CT) formed in the reaction of the electron donor 4-(aminomethyl) piperidine (4AMP) with the σ-acceptor iodine and the π-acceptors 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ), 2,4,4,6-tetrabromo-2,5-cyclohexadienone (TBCHD) and 7,7,8,8-tetracyanoquinodimethane (TCNQ) have been studied in chloroform at 25°C. These were investigated through electronic, infrared spectra and thermal analysis as well as elemental analysis. The results show that the formed solid CT-complexes have the formulas [(4AMP)I](+)I3(-), [(4AMP)(DDQ)2] and [(4AMP)(TBCHD)] while in the case of 4AMP-TCNQ reaction, a short-lived CT complex is formed followed by rapid N-substitution by TCNQ forming the final reaction product 7,7,8-tricyano-8-aminomethylpiperidinylquinodimethane [TCAMPQDM] in full agreement with the known reaction stoichiometries in solution as well as the elemental measurements and the thermal analysis confirmed the structure of the obtained compounds. The formation constant kCT, molar extinction coefficient εCT, free energy change ΔG(0) and CT energy ECT have been calculated for the CT-complexes [(4AMP)I](+)I3(-), [(4AMP)(DDQ)2] and [(4AMP)(TBCHD)].