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Abstract: The spectrophotometric characteristics of the solid charge–transfer molecular complexes (CT) formed in the reaction of the electron donors imidazole (IML) and 1-benzylimidazole (BIML) with the σ-acceptor iodine and π-acceptors 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ), tetracyanoethylene (TCNE) and 2,3,5,6-tetrachloro-1,4-benzoquinone (CHL) have been studied in chloroform at 25°C. These were investigated through electronic and infrared spectra as well as elemental analysis. The results show that the formed solid CT-complexes have the formulas [(IML)2 I]I3, [(IML)(DDQ)], [(IML)2(TCNE)5] and [(IML)(CHL)] for imidazole and [(BIML) I]I3, [(BIML)(DDQ)2], [(BIML)(TCNE)2] and [(BIML)(CHL)2] for 1-benzylimidazole in full agreement with the known reaction stoichiometries in solution as well as the elemental measurements. The formation constant K CT, molar extinction coefficient ɛ CT, free energy change ΔG 0, CT energy E CT and ionization potential Ip have been calculated for the CT-complexes [(IML)2 I]I3, [(IML)(DDQ)], [(IML)(CHL)], [(BIML) I]I3, [(BIML)(DDQ)2], [(BIML)(TCNE)2] and [(BIML)(CHL)2]. [Copyright &y& Elsevier]

Abstract: Novel charge transfer complexes have been formed in the reaction of the interesting powerful electron donor 1,4,7,10,13,16-hexamethyl-1,4,7,10,13,16-hexaazacyclooctadecane (HMHACOD) with σ-electron acceptor iodine and π-acceptors tetracynoethylene (TCNE) and 7,7,8,8,-tetracyanoquinodimethane (TCNQ). The reactions have been studied spectrophotometrically in chloroform and the formed solid complexes have been isolated and characterized through infrared spectra as well as thermal and elemental analysis. Due to the expected powerful electron donation of the donor (HMHACOD), the reaction stoichiometries, donor:acceptor molar ratio values, are found to be exceptionally high equal to 1:6, 1:16 and 1:3 for iodine, TCNE and TCNQ complexes, respectively. Accordingly the formed charge transfer complexes could be formulated as [(HMHACOD)I]+·, [(HMHACOD)(TCNE)16] and [(HMHACOD)(TCNQ)3]. [Copyright &y& Elsevier]

Abstract: Charge-transfer complexes between 1-methylpiperazine (1MPIPZ) as a donor with the π-acceptors 7,7,8,8-tetracyanoquinodimethane (TCNQ), tetracyanoethylene (TCNE), 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ), 2,3,5,6-tetrachloro-1,4-benzoquinone (chloranil=CHL) and σ-acceptor iodine (I2) have been studied spectrophotometrically in chloroform at room temperature by electronic and infrared spectra as well as elemental and thermal analysis. The obtained results indicate the formation of 1:3M ratio for 1MPIPZ with TCNQ and TCNE, and 1:1M ratio for 1MPIPZ with DDQ, CHL, and I2. Based on the obtained data, the formed charge-transfer complexes were formulated as [(1MPIPZ)(TCNQ)3], [(1MPIPZ) (TCNE)3], [(1MPIPZ)(DDQ)], [(1MPIPZ)(CHL)] and [(1MPIPZ)2I]+ . [Copyright &y& Elsevier]

Abstract: The reactions of the electron donor 1-methylpiperidine (1MP) with the π-acceptors 7,7,8,8-tetracyanoquinodimethane (TCNQ), tetracyanoethylene (TCNE), 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ), 2,3,5,6-tetrachloro-1,4-benzoquinone (chloranil=CHL) and iodine (I2) were studied spectrophotometrically in chloroform at room temperature. The electronic and infrared spectra of the formed molecular charge-transfer (CT) complexes were recorded. The obtained results showed that the stoichiometries of the reactions are not fixed and depend on the nature of the acceptor. Based on the obtained data, the formed charge-transfer complexes were formulated as [(1MP)(TCNE)2], [(1MP)(DDQ)]·H2O, [(1MP)(CHL)] and [(1MP)I]I3, while in the case of 1MP–TCNQ reaction, a short-lived CT complex is formed followed by rapid N-substitution by TCNQ forming the final reaction products 7,7,8-tricyano-8-piperidinylquinodimethane (TCPQDM). The five solids products were isolated and have been characterized by electronic spectra, infrared spectra, elemental analysis and thermal analysis. [Copyright &y& Elsevier]

Abstract: The interactions of the electron donors 2-aminopyridine (2APY) and 3-aminopyridine (3APY) with the π-acceptors tetracyanoethylene (TCNE), 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ), 2-chloro-1,3,5-trinitrobenzene (picryl chloride, PC), and 2,3,5,6-tetrachloro-1,4-benzoquinone (chloranil) were studied spectrophotometrically in chloroform at room temperature. The electronic and infrared spectra of the formed molecular charge transfer (CT) complexes were recorded. Photometric titration showed that the stoichiometries of the reactions were fixed and depended on the nature of both the donor and the acceptor. The molecular structures of the CT-complexes were, however, independent of the position of the amino group on the pyridine ring and were formulated as [(APY)(TCNE)], [(APY)(DDQ)], [(APY)(PC)], and [(APY) (chloranil)]. The formation constants (K CT), charge transfer energy (E CT) and molar extinction coefficients (ɛ CT) of the formed CT-complexes were obtained. [Copyright &y& Elsevier]

Abstract: The solid charge-transfer complexes formed in the reaction of the electron donor 1,4,7-trimethyl-1,4,7-triazacyclononane (TMTACN) with the acceptors iodine, tetracyanoethylene (TCNE) and 7,7,8,8-tetracyanoquinodimethane (TCNQ) have been isolated. These were characterized through electronic and infrared spectra as well as thermal and elemental analysis. The results show that the formed solid CT-complexes have the formulas [(TMTACN)I]I3, [(TMTACN)(TCNE)5] and [(TMTACN)(TCNQ)3] in full agreement with the known reaction stoichiometries in solution. The chloranil CT-solid complex cannot be isolated in pure form. [Copyright &y& Elsevier]

Abstract: The interactions of the electron donors piperazine (PIP) and N,N′-dimethylpiperazine (DMPIP) with the σ-acceptor iodine and the π-acceptors tetracyanoethylene (TCNE) and 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) were studied spectrophotometrically in chloroform at 25°C. The electronic and infrared spectra of the resulting charge-transfer complexes were recorded, in addition to thermal analysis. The results obtained showed that the stoichiometries of the reactions are not fixed and depend on the nature of both the donor and the acceptor. The formed CT-complexes have the formulas of , [(PIP)(TCNE)2], [(PIP)(DDQ)2], , [(DMPIP)(TCNE)2] and [(DMPIP)(DDQ)2]. A general mechanism explaining the formation of triiodide complexes was suggested. [Copyright &y& Elsevier]

Abstract: Molecular charge-transfer complexes of the donor 2,6-diaminopyridine (2,6-DAPY) with π-acceptors tetracyanoethylene (TCNE), 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ) and tetrachloro-p-benzoquinone(chloranil) were studied spectrophotometrically in chloroform at room temperature. All formed complexes exhibit well resolved charge-transfer bands in the regions where neither donor nor acceptors have any absorption. The stoichiometries of the reactions were determined from photometric titration methods. The results obtained show the formed CT complexes have the structures [(2,6-DAPY)(TCNE)3], [(2,6-DAPY)(DDQ)2], and [(2,6-DAPY)(chloranil)]. These three complexes were isolated as solids and further characterized by elemental analysis and infrared measurements. [Copyright &y& Elsevier]

Abstract: The charge transfer interaction of the interesting mixed nitrogen–oxygen donor 4,7,13,16,21,24-hexaoxa-1,10-diazabicyclo[8,8,8]hexacosane (HODABCHC) with σ-electron acceptor iodine and π-acceptors tetracyanoethylene (TCNE) and 7,7,8,8-tetracyanoquinodimethane (TCNQ) have been investigated spectrophotometrically in chloroform. FT-IR, thermal and elemental analysis measurements are performed for the solid CT-interaction products. The reaction stoichiometries were found to be 1:4, 1:6 and 1:3 donor:acceptor molar ratio for iodine, TCNE and TCNQ reaction systems, respectively. The obtained relatively high reaction stoichiometry values are expected due to the expected high electron donation of the donor (HODABCHC). It contains six oxygen and two nitrogen donor atoms. Accordingly, the formed charge transfer complexes could be formulated as , [(HODABCHC)(TCNE)6] and [(HODABCHC)(TCNQ)3]. [Copyright &y& Elsevier]

Abstract: Three novel aqueous and solid charge-transfer complexes are synthesized by the reaction of the polynitrogen cyclic n-donor 1,4,8,11-tetraazacyclotetradecane-5,7-dione (TACTDD) with the σ-acceptor iodine, the aliphatic π-acceptor tetracyanoethylene (TCNE) as well as with the aromatic π-acceptor 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) using chloroform as the medium solvent. Photometric titration measurements of the CT-solution complexes confirm the donor to acceptor ratios are 1:2 for TACTDD–I2 and TACTDD–TCNE reactions while is 1:1 for the reaction TACTDD–DDQ. These reaction stoichiometries are supported by the elemental, thermal and infrared measurements for the formed CT-solids. Accordingly, the reaction products are formulated as [(TACTDD) I]⋅I3, [(TACTDD)(TCNE)2] and [(TACTDD)(DDQ)]. The effect of the substituents, electron donating or withdrawing groups in the donor and acceptors compositions on their CT-interactions is discussed. [ABSTRACT FROM AUTHOR]