作者:Sidonie Finck、Jean-Thomas Issenhuth、Stéphane Despax、Claude Sirlin、Michel Pfeffer、Corentin Poidevin、Christophe Gourlaouen、Alex Boeglin、Chantal Daniel
DOI:10.1016/j.jorganchem.2013.08.032
日期:2014.6
The electronic spectra of 4 cyclometalated ruthenium compounds built up from cycloruthenated 2-phenylpyridine with monodentate and bidentate ligands, namely (1) under bar1 [Ru(MeCN)(2)(phen)(PhPy)](1+) (RDC11), (2) under bar [Ru(phen)(2)(PhPy)](1+) (RDC34), (3) under bar [Ru(MeCN)(2)(PhPy)(dppz)](1+) (RDC11Z), (4) under bar [Ru(bpy) (PhPy)(dppz)](1+) (RDCbpZ), the last two being newly synthesized, have been recorded and calculated together with that of (5) under bar [Ru(bpy)(2)(dppz)](2+) (RDNbpZ). Recently synthesized variants of RDC34 where the phenylpyridine ligand is substituted with an electro-attractor or an electro-donor group, (6) under bar [Ru(phen)(2)(NO2PhPy)](1+) RDC40 and (7) under bar [Ru(phen)(2)(NH2PhPy)](1+) RDC41 respectively, and the dicationic reference complex [Ru (phen)(2)(bpy)](2+) (RDN34) have been investigated as well for comparison. The global structures of RDC34 and RDN34 are very similar despite of the substitution of one N atom by one C atom. As expected a shortening of the Ru-C bond as compared to the Ru-N bond is observed. The calculated structures of the investigated complexes point to a rather rigid structure whatever their environment. The introduction of a strong Ru-C bond has a minor effect on the coordination sphere around the metal atom keeping the other Ru-N bonds and bond angles similar, the only noticeable alteration being an increase of the Ru-N bond trans to the Ru-C bond. The experimental spectra are characterized by an intense band in the UV domain centered at 270 nm and corresponding to a strong intra-ligand (IL) absorption. Low-lying MLCT states contribute to a weak shoulder around 370 nm and to a large band between 550 nm and 400 nm. The tail of this band, towards 650 nm, is a characteristic of the cyclometalated complexes. This series of molecules, as other polypyridyl complexes, are characterized by a high density of excited states in the vis/UV energy domain, a large mixing between MLCT/IL and LLCT states in the upper part of the spectrum, and a significant sensitivity to the environment of the IL state localized on the dppz ligands. (C) 2013 Published by Elsevier B.V.