CHARGE TRANSFER MOLECULAR COMPLEXES OF 4-(DIMETHYLAMINO)PYRIDINE WITH SOME CONVENTIONAL AND UNCONVENTIONAL ACCEPTORS INVOLVING FLUOROARENES

摘要

Charge transfer (CT)complexes of 4-(dimethylamino)pyridine (DMAP)with iodine as a typical sigma-type acceptor and with typical pi-type acceptor,2,3-dichloro-5,6-dicyano-l,4-benzoquinone (DDQ),have been synthesized and characterized.Octafluorotoluene (OFT),octafluoro-naphthalene (OFN),perfluorophenanthrene (PFP),and 2,3,5,6-tetrafluoropyridine-4-carbo-nitrile (TFP)were also used as acceptors for interaction with DMAP.Properties of such CT complexes were investigated by UV/VIS and IR spectra,and elemental analyses of the isolated complexes.The systems DMAP-iodine and DMAP-DDQ are characterized by formation of triiodide ions (I_3~-)and DDQ~(centre dot-)anion radicals,respectively,which is proposed to occur via initial formation of outer-sphere CT complexes.The systems (DMAP-OFT,DMAP-OFN,DMAP-PFP and DMAP-TFP)are characterized by the appearance of new UV/VIS spectral bands assigned as CT bands; they also furnished the corresponding solid complexes with the stoichiometric ratio 1:1.~1H and ~(19)F NMR spectra were used on confirming the formation of the DMAP-PFP CT complexes.The formation constants (K_(CT))and molar absorption coefficients (omega_(CT))of the latter complex were obtained.