Charge transfer spectra and photoreactivity of (E)-1-ferrocenyl-2-(1-methyl-4-pyridiniumyl)ethylene cation

The electronic spectrum of (E)-1-ferrocenyl-2-(1-methyl-4-pyridiniumyl)ethy lene (E-fmpe(+)) cation shows two long-wavelength absorptions near 570 and 370 nm which are assigned to metal-to-ligand charge transfer (MLCT) and int raligand charge transfer (ILCT) transitions, respectively. The complex disp lays a strong negative solvatochromism. MLCT as well as ILCT excitation lea ds to a trans/cis isomerization at the olefinic double bond. The complex is photochromic since the photoisomerization is thermally reversed. The ion p air E-fmpe(+)[Fe(CN)(6)](4-) shows a photoactive outer-sphere charge transf er absorption at lambda (max) = 490 nm. (C) 2001 Elsevier Science B.V. All rights reserved.