posted on 2003-09-30, 00:00authored byJulia A. Weinstein, Alexander J. Blake, E. Stephen Davies, Adrienne L. Davis, Michael W. George, David C. Grills, Igor V. Lileev, Alexander M. Maksimov, Pavel Matousek, Mikhail Ya. Mel'nikov, Anthony W. Parker, Vyacheslav E. Platonov, Michael Towrie, Claire Wilson, Natalia N. Zheligovskaya
The synthesis of new PtII diimine complexes bearing perfluorinated thiolate ligands, PtII(NN)(4-X−C6F4−S)2, where
NN = 2,2‘-bipyridine or 1,10-phenanthroline and X = F or CN, is reported, together with an investigation of the
nature and dynamics of their lowest excited states. A combined UV−vis, (spectro)electrochemical, resonance Raman,
and time-resolved infrared (TRIR) study has suggested that the HOMO is mainly composed of thiolate(π)/S(p)/Pt(d) orbitals and that the LUMO is largely localized on the π* (diimine) orbital, thus revealing the {charge-transfer-to-diimine} nature of the lowest excited state. An enhancement of the thiolate ring vibrations, C−F vibrations, and
the vibration of the CN-substituent on the thiolate moiety was observed in the resonance Raman spectra, whereas
no such enhancement was seen for the nonfluorinated analogues. Thus, the introduction of fluorine substituents on
the thiolate moiety probably leads to a more pronounced contribution of the intrathiolate modes to the HOMO
compared to the analogous complexes with nonfluorinated thiolates. Furthermore, the introduction of the p-CN
group into the thiolate moiety has allowed the dynamics of the lowest excited state of Pt(bpy)(4-CN−C6F4−S)2 to
be monitored by picosecond TRIR spectroscopy. The dynamics of the lowest {charge-transfer-to-diimine} excited
state are governed by ca. 2-ps vibrational cooling and 35-ps back electron transfer.