Synthesis, Characterization, and Electrochemistry of Biorelevant Photosensitive Low-Potential Orthometalated Ruthenium Complexes
详细信息 查看全文
- 作者：Alexander D. Ryabov ; Ronan Le Lagadec ; Hebert Estevez ; Ruben A. Toscano ; Simon Hernandez ; Larissa Alexandrova ; Viktoria S. Kurova ; Andreas Fischer ; Claude Sirlin ; and Michel Pfeffer
- 刊名：Inorganic Chemistry
- 出版年：2005
- 出版时间：March 7, 2005
- 年：2005
- 卷：44
- 期：5
- 页码：1626 - 1634
- 全文大小：205K
- 年卷期：v.44,no.5(March 7, 2005)
- ISSN：1520-510X
文摘
Redox potentials of photosensitive cyclometalated RuII derivatives of 2-phenylpyridine or 2-(4-tolyl)pyridine arecontrollably decreased by up to 0.8 V within several minutes. This is achieved by irradiation of the ruthena(II)cyclescis-[Ru(o-X-2-py)(LL)(MeCN)2]PF6 (2, X = C6H4 (a) or 4-MeC6H3 (b), LL = 1,10-phenanthroline or 2,2'-bipyridine).The cis geometry of the MeCN ligands has been confirmed by the X-ray structural studies. The 
s/gifchars/sigma.gif" BORDER=0 >-bound sp2carbon of the metalated ring is trans to LL nitrogen. Complexes 2 are made from [Ru(o-X-2-py)(MeCN)4]PF6 (1)and LL. This "trivial" ligand substitution is unusual because 1a reacts readily with phen in MeCN as solvent to givecis-[Ru(o-C6H4-2-py)(phen)(MeCN)2]PF6 (2c) in a 83% yield, but bpy does not afford the bpy-containing 2 underthe same conditions. cis-[Ru(o-C6H4-2-py)(bpy)(MeCN)2]PF6 (2e) has been prepared in CH2Cl2 (74%). Studies ofcomplexes 2c,e by cyclic voltammetry in MeOH in the dark reveal RuII/III quasy-reversible redox features at 573and 578 mV (vs Ag/AgCl), respectively. A minute irradiation 2c and 2e converts them into new species with redoxpotentials of -230 and 270 mV, respectively. An exceptional potential drop for 2c is accounted for in terms of aphotosubstitution of both MeCN ligands by methanol. ESR, 1H NMR, and UV-vis data indicate that the primaryproduct of photolysis of 2c is an octahedral monomeric low-spin (S = 1/2) RuIII species, presumably cis-[RuIII(o-C6H4-2-py)(phen)(MeOH)2]2+. The primary photoproduct of bpy complex 2e is cis-[RuII(o-C6H4-2-py)(bpy)(MeCN)(MeOH)]+, and this accounts for a lower decrease in the redox potential. Irradiation of 2c in the presence of addedchloride affords [(phen)(o-C6H4-2-py)ClRuIIIORuIVCl(o-C6H4-2-py)(phen)]PF6, a first s/entities/mgr.gif">-oxo-bridged mixed valent dimerwith a cyclometalated unit. The structure of the dimer has been established by X-ray crystallography.