Oxo-Centered Mixed-Ligand Triruthenium Complexes Having Redox-Active N-Methyl-4,4'-bipyridinium Ions (mbpy+). Reversible Multistep Electrochemical Properties of [RuIII
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- 作者：Masaaki Abe ; Yoichi Sasaki ; Yasuko Yamada ; Keiichi Tsukahara ; Shigenobu Yano ; Tadashi Yamaguchi ; Masato Tominaga ; Isao Taniguchi ; and Tasuku Ito
- 刊名：Inorganic Chemistry
- 出版年：1996
- 出版时间：November 6, 1996
- 年：1996
- 卷：35
- 期：23
- 页码：6724 - 6734
- 全文大小：357K
- 年卷期：v.35,no.23(November 6, 1996)
- ISSN：1520-510X
文摘
A new series of oxo-centered acetate-bridged triruthenium comlexeshaving two redox-active N-methyl-4,4'-bipyridinium ions (mbpy+) have been prepared, and theirreversible multistep and multielectron electrochemicalproperties are reported:[RuIII2RuII(
3-O)(-CH3CO2)6(mbpy+)2(CO)]2+and[RuIII3(3-O)(-CH3CO2)6(mbpy+)2(L)]3+ (L = H2O, pyrazine (pz), pyridine(py), imidazole (Him), and 4-(dimethylamino)pyridine (dmap)).Amongthese series, the CO complex,[RuIII2RuII(3-O)(-CH3CO2)6(mbpy+)2(CO)](ClO4)2·2DMF(1b·2DMF) wasstructurally characterized by X-ray crystallography.1b·2DMF crystallizes in the monoclinic spacegroup P21/m(No. 11) with a = 8.740(6) Å, b =32.269(6) Å, c = 10.276(4) Å, 
=103.37(5)
, V = 2820(2) Å3,Z = 2, dcalcd= 1.636 g cm-3, and R = 0.071(Rw = 0.074) for 5277 independent reflections(
Fo >3
(Fo). The(CO)Ru···Ru distance (3.410(2) Å) is appreciably longerthan the other Ru···Ru distance (3.276(2) Å),indicating thatthe trinuclear core is in the valence-trappedRuIII2RuII(CO) oxidationstate. The cyclic voltammogram of[RuIII2RuII(3-O)(-CH3CO2)6(mbpy+)2(CO)](PF6)2(1a) shows a total of seven reversible one-electron redoxstepsat E1/2 = +0.90, +0.26, -1.07,-1.17, -1.56, -1.97, and -2.32 V and one irreversible step atEpc = -2.99 Vvs Fc/Fc+ in a 0.1 M[(n-C4H9)4N]PF6-CH3CNsolution (M = mol dm-3). All of thewaves are clearly assignableto the triruthenium "Ru3(3-O)"core-based or mbpy+ ligand-based processes. Thesplitting of each ligand-basedredox processes (mbpy+/mbpy
andmbpy/mbpy-) into two one-electron stepsindicates that electronic interactionsbetween two terminal ligands occur through the triruthenium clustercore. Other mixed-ligand RuIII3analogsalso show multistep redox behavior involving a total of eight or nineelectrons. While the extent of interactionsbetween ligands is much smaller than that found in the CO complex, itis systematically changed by the natureof L; with more basic L, interactions between two mbpy+ligands become larger.
3-O)(-CH3CO2)6(mbpy+)2(CO)]2+and[RuIII3(3-O)(-CH3CO2)6(mbpy+)2(L)]3+ (L = H2O, pyrazine (pz), pyridine(py), imidazole (Him), and 4-(dimethylamino)pyridine (dmap)).Amongthese series, the CO complex,[RuIII2RuII(3-O)(-CH3CO2)6(mbpy+)2(CO)](ClO4)2·2DMF(1b·2DMF) wasstructurally characterized by X-ray crystallography.1b·2DMF crystallizes in the monoclinic spacegroup P21/m(No. 11) with a = 8.740(6) Å, b =32.269(6) Å, c = 10.276(4) Å, =103.37(5), V = 2820(2) Å3,Z = 2, dcalcd= 1.636 g cm-3, and R = 0.071(Rw = 0.074) for 5277 independent reflections(Fo >3(Fo). The(CO)Ru···Ru distance (3.410(2) Å) is appreciably longerthan the other Ru···Ru distance (3.276(2) Å),indicating thatthe trinuclear core is in the valence-trappedRuIII2RuII(CO) oxidationstate. The cyclic voltammogram of[RuIII2RuII(3-O)(-CH3CO2)6(mbpy+)2(CO)](PF6)2(1a) shows a total of seven reversible one-electron redoxstepsat E1/2 = +0.90, +0.26, -1.07,-1.17, -1.56, -1.97, and -2.32 V and one irreversible step atEpc = -2.99 Vvs Fc/Fc+ in a 0.1 M[(n-C4H9)4N]PF6-CH3CNsolution (M = mol dm-3). All of thewaves are clearly assignableto the triruthenium "Ru3(3-O)"core-based or mbpy+ ligand-based processes. Thesplitting of each ligand-basedredox processes (mbpy+/mbpy andmbpy/mbpy-) into two one-electron stepsindicates that electronic interactionsbetween two terminal ligands occur through the triruthenium clustercore. Other mixed-ligand RuIII3analogsalso show multistep redox behavior involving a total of eight or nineelectrons. While the extent of interactionsbetween ligands is much smaller than that found in the CO complex, itis systematically changed by the natureof L; with more basic L, interactions between two mbpy+ligands become larger.