Electron transfer reactions of (C5R5)2(CO)2Ti (R=H or Me) with TCNE or TCNQ

The TCNX ligands TCNE (tetracyanoethene) and TCNQ (7,7,8,8-tetracyano-p-quinodimethane) react instantaneously with (C5R5)2(CO)2Ti, R=H or Me, to yield highly air-sensitive mononuclear complexes (C5R5)2(CO)Ti(TCNX) of which the soluble species (R=Me) were characterized also in the oxidized and reduced forms through cyclic voltammetry, EPR, IR and UV–vis spectroelectrochemistry. While oxidation at rather low potentials yields labile carbonyltitanium(IV) species of the TCNX− ligands, the reduction occurs stepwise at unusually negative potentials, first on the ligand (to yield coordinated TCNX2−) and then on the metal (to form TiII). For the neutral complexes (C5R5)2(CO)Ti2+q(TCNX−q) the results support a rather large amount of charge transfer 1