TY - JOUR
T1 - Oxo-Centered Mixed-Ligand Triruthenium Complexes Having Redox-Active N-Methyl-4,4′-bipyridinium Ions (mbpy+). Reversible Multistep Electrochemical Properties of [Ru2IIIRuII(μ3-O)(μ-CH3CO 2)6(mbpy+)2(CO)]2+
AU - Abe, Masaaki
AU - Sasaki, Yoichi
AU - Yamada, Yasuko
AU - Tsukahara, Keiichi
AU - Yano, Shigenobu
AU - Yamaguchi, Tadashi
AU - Tominaga, Masato
AU - Taniguchi, Isao
AU - Ito, Tasuku
PY - 1996
Y1 - 1996
N2 - A new series of oxo-centered acetate-bridged triruthenium comlexes having two redox-active N-methyl-4,4′-bipyridinium ions (mbpy+) have been prepared, and their reversible multistep and multielectron electrochemical properties are reported: [Ru2IIIRuII(μ3-O)(μ-CH 3CO2)6(mbpy+2(CO)] 2+ and [Ru3III(μ3-O)(μ-CH3CO 2)6(mbpy+)2-(L)]3+ (L = H2O, pyrazine (pz), pyridine (py), imidazole (Him), and 4-(dimethylamino)pyridine (dmap)). Among these series, the CO complex, [Ru2IIIRuII(μ3-O)(μ-CH 3CO2)6(mbpy+) 2(CO)](ClO4)2·2DMF (1b·2DMF) was structurally characterized by X-ray crystallography. 1b·2DMF crystallizes in the monoclinic space group P21/m (No. 11) with a = 8.740(6) Å, b = 32.269(6) Å, c = 10.276(4) Å, β = 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| > 3σ(|Fo|). The (CO)-Ru⋯Ru distance (3.410(2) Å) is appreciably longer than the other Ru⋯Ru distance (3.276(2) Å), indicating that the trinuclear core is in the valence-trapped Ru2IIIRuII(CO) oxidation state. The cyclic voltammogram of [Ru2IIIRuII(μ3-O)(μ-CH 3CO2)6(mbpy+) 2(CO)](PF6)2 (1a) shows a total of seven reversible one-electron redox steps at E1/2 = +0.90, +0.26, -1.07, -1.17, -1.56, -1.97, and -2.32 V and one irreversible step at Epc = -2.99 V vs Fc/Fc+ in a 0.1 M [(n-C4H9)4N]PF6-CH3CN solution (M = mol dm-3). All of the waves are clearly assignable to the triruthenium "Ru3(μ3-O)" core-based or mbpy+ ligand-based processes. The splitting of each ligand-based redox processes (mbpy+/mbpy' and mbpy/mbpy-) into two one-electron steps indicates that electronic interactions between two terminal ligands occur through the triruthenium cluster core. Other mixed-ligand Ru3III analogs also show multistep redox behavior involving a total of eight or nine electrons. While the extent of interactions between ligands is much smaller than that found in the CO complex, it is systematically changed by the nature of L; with more basic L, interactions between two mbpy+ ligands become larger.
AB - A new series of oxo-centered acetate-bridged triruthenium comlexes having two redox-active N-methyl-4,4′-bipyridinium ions (mbpy+) have been prepared, and their reversible multistep and multielectron electrochemical properties are reported: [Ru2IIIRuII(μ3-O)(μ-CH 3CO2)6(mbpy+2(CO)] 2+ and [Ru3III(μ3-O)(μ-CH3CO 2)6(mbpy+)2-(L)]3+ (L = H2O, pyrazine (pz), pyridine (py), imidazole (Him), and 4-(dimethylamino)pyridine (dmap)). Among these series, the CO complex, [Ru2IIIRuII(μ3-O)(μ-CH 3CO2)6(mbpy+) 2(CO)](ClO4)2·2DMF (1b·2DMF) was structurally characterized by X-ray crystallography. 1b·2DMF crystallizes in the monoclinic space group P21/m (No. 11) with a = 8.740(6) Å, b = 32.269(6) Å, c = 10.276(4) Å, β = 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| > 3σ(|Fo|). The (CO)-Ru⋯Ru distance (3.410(2) Å) is appreciably longer than the other Ru⋯Ru distance (3.276(2) Å), indicating that the trinuclear core is in the valence-trapped Ru2IIIRuII(CO) oxidation state. The cyclic voltammogram of [Ru2IIIRuII(μ3-O)(μ-CH 3CO2)6(mbpy+) 2(CO)](PF6)2 (1a) shows a total of seven reversible one-electron redox steps at E1/2 = +0.90, +0.26, -1.07, -1.17, -1.56, -1.97, and -2.32 V and one irreversible step at Epc = -2.99 V vs Fc/Fc+ in a 0.1 M [(n-C4H9)4N]PF6-CH3CN solution (M = mol dm-3). All of the waves are clearly assignable to the triruthenium "Ru3(μ3-O)" core-based or mbpy+ ligand-based processes. The splitting of each ligand-based redox processes (mbpy+/mbpy' and mbpy/mbpy-) into two one-electron steps indicates that electronic interactions between two terminal ligands occur through the triruthenium cluster core. Other mixed-ligand Ru3III analogs also show multistep redox behavior involving a total of eight or nine electrons. While the extent of interactions between ligands is much smaller than that found in the CO complex, it is systematically changed by the nature of L; with more basic L, interactions between two mbpy+ ligands become larger.
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U2 - 10.1021/ic960430j
DO - 10.1021/ic960430j
M3 - Article
AN - SCOPUS:0001582936
SN - 0020-1669
VL - 35
SP - 6724
EP - 6734
JO - Inorganic Chemistry
JF - Inorganic Chemistry
IS - 23
ER -