Tuning of Metal-Metal Interactions in Mixed-Valence States of Cyclometalated Dinuclear Ruthenium and Osmium Complexes Bearing Tetrapyridylpyrazine or -benzene

doi:10.1021/om500142t

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	Tuning of Metal-Metal Interactions in Mixed-Valence States of Cyclometalated Dinuclear Ruthenium and Osmium Complexes Bearing Tetrapyridylpyrazine or -benzene
	Nagashima, Takumi 1; Nakabayashi, Takuya 1; Suzuki, Takashi 1; Kanaizuka, Katsuhiko 1; Ozawa, Hiroaki 1; Zhong, Yu-Wu 2; Masaoka, Shigeyuki 3; Sakai, Ken 4; Haga, Masa-aki 1
刊名	ORGANOMETALLICS
	2014-09-22
卷号	33 期号:18 页码:4893-4904
ISSN号	0276-7333
DOI	10.1021/om500142t
英文摘要	New dinuclear ruthenium or osmium complexes with cyclometalated bonds in either tridentate bridging (BL) or ancillary ligands (L), [(L)M(BL)M(L)] (where M = Ru, Os; L = bis(N-methylbenzimidazolyl)pyridine, -benzene; BL= tetrapyridylpyrazine (tppz), -benzene (tpb)), were synthesized, and their mixed-valence-state characteristics were investigated. All of the complexes showed successive one-electron redox processes, each of which correspond to M(II/III) (M = Ru, Os) or ligand reduction waves. In addition, an M(III/IV) couple was observed in cyclometalated [M-2(bis-(benzimidazolyl)benzene)(2)(BL)] complexes (M = Ru, Os). Effects of the cyclometalated bonds on the redox behaviors and the accessibility to the mixed-valence M(II)-M(III) dinuclear complexes are discussed. Introduction of a cyclometalated bond induced a large negative potential shift in the redox potentials of dinuclear ruthenium and osmium complexes, depending on either bridging or ancillary sites of the cyclometalated bonds: the change falls within the range of -1.0 to -1.2 V for the bridging sites and -0.65 to -0.7 V for the ancillary ones. This large negative potential shift arises from the strong electron-donating property of the phenyl anion in a metal C bond. Replacing the ruthenium by osmium in the dinuclear complexes with the same bridging ligand results in an increase of the potential separation (Delta E(1)) and the comproportionation constant (K-com) of the mixed-valence complexes having the tppz bridging ligand (Delta E(1) and K-com values: Os > Ru); however, complexes having the tpb bridging ligand showed the opposite trend (Delta E(1) and K-com: Os < Ru). In addition to the results of EPR and DFT calculation, it was found that the orbital energy levels of the central metal ion (namely, either Ru or Os) in the mixed-valence complex determines the degree of orbital mixing between metal d pi orbitals and bridging-ligand pi or pi* orbitals, which leads to either hole- or electron-transfer exchange mechanisms.
语种	英语
出版者	AMER CHEMICAL SOC
WOS记录号	WOS:000342180800036
内容类型	期刊论文
源URL	[http://ir.iccas.ac.cn/handle/121111/51149]
专题	中国科学院化学研究所
通讯作者	Haga, Masa-aki
作者单位	1.Chuo Univ, Dept Appl Chem, Fac Sci & Engn, Bunkyo Ku, Tokyo 1128551, Japan 2.Chinese Acad Sci, Inst Chem, CAS Key Lab Photochem, Beijing Natl Lab Mol Sci, Beijing 100190, Peoples R China 3.Natl Inst Nat Sci, Inst Mol Sci, Okazaki, Aichi 4448787, Japan 4.Kyushu Univ, Dept Chem, Fac Sci, Higashi Ku, Fukuoka 8128581, Japan
推荐引用方式 GB/T 7714	Nagashima, Takumi,Nakabayashi, Takuya,Suzuki, Takashi,et al. Tuning of Metal-Metal Interactions in Mixed-Valence States of Cyclometalated Dinuclear Ruthenium and Osmium Complexes Bearing Tetrapyridylpyrazine or -benzene[J]. ORGANOMETALLICS,2014,33(18):4893-4904.
APA	Nagashima, Takumi.,Nakabayashi, Takuya.,Suzuki, Takashi.,Kanaizuka, Katsuhiko.,Ozawa, Hiroaki.,...&Haga, Masa-aki.(2014).Tuning of Metal-Metal Interactions in Mixed-Valence States of Cyclometalated Dinuclear Ruthenium and Osmium Complexes Bearing Tetrapyridylpyrazine or -benzene.ORGANOMETALLICS,33(18),4893-4904.
MLA	Nagashima, Takumi,et al."Tuning of Metal-Metal Interactions in Mixed-Valence States of Cyclometalated Dinuclear Ruthenium and Osmium Complexes Bearing Tetrapyridylpyrazine or -benzene".ORGANOMETALLICS 33.18(2014):4893-4904.