Synthesis, Structural, Spectroscopic and Electrochemical Characterization of New Ruthenium(II) Tetramer Complexes Containing 1,4-Bis(diphenylphosphine)butane and Alterdentate Ligands

Queiroz, Salete Linhares; Kikuti, Elaine; Ferreira, Antônio G.; Santiago, Maria Marlúcia Freitas; Batista, Alzir A.; Castellano, Eduardo E.; Ellena, Javier

doi:10.1080/1061027042000201644

Cited by 6 publications

(8 citation statements)

References 27 publications

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“…Of particular interest are the interpyridine ring twist angles, which are φ = 1.0 and 5.6° for opposing pairs of 4,4‘-bpy ligands. Although these twist angles are greater than those found within the triangular complex, they are significantly lower than observed in the crystal structures of other 4,4‘-bpy-bridged squares, 17c,j including [(dppb) 4 Ru 4 Cl 8 (4,4‘-bpy) 4 ] (φ = 10.9° and 42.6°) . Very likely, the small twist angles are a result of the packing arrangement within the crystal, and are not retained upon dissolution.…”

Section: Resultsmentioning

confidence: 61%

“…A number of molecular squares have been constructed using 4,4‘-bpy as a linker. , In the cases where these complexes have been crystallized, however, the pyridyl rings within each bridging unit are far from coplanar (typically, φ = 25−37°). 17cj, In addition, it has been suggested on the basis of solution NMR experiments that the square complex [(2,2‘-bpy) 4 Pd 4 (4,4‘-bpy) 4 ] 8+ is actually in equilibrium with a 4,4‘-bpy-bridged molecular triangle: [(2,2‘-bpy) 3 Pd 3 (4,4‘-bpy) 3 ] 6+ 17e. Although none have yet been isolated in pure form, triangles of this type are of considerable interest, because the strain arising because of the discrepancy between the triangle corner angle of 60° and the preferred N−M−N angle of 90° can be anticipated to force all bridging pyridyl rings to be perpendicular to the plane of the triangle.…”

Section: Introductionmentioning

confidence: 99%

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Angle-Dependent Electronic Effects in 4,4‘-Bipyridine-Bridged Ru₃ Triangle and Ru₄ Square Complexes

et al. 2006

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Use of 1,4,7,10-tetraazacyclododecane (cyclen) as a capping ligand and 4,4'-bipyridine (4,4'-bpy) as a bridging ligand enables assembly of redox-active Ru3 triangle and Ru4 square complexes. The former is produced by reacting [(cyclen)Ru(DMSO)Cl]Cl with 4,4'-bpy in a 3:1 ethanol:water mixture to precipitate [(cyclen)3Ru3(4,4'-bpy)3]Cl6.18H2O.THF (4), whereas the latter is generated as [(cyclen)4Ru4(4,4'-bpy)4](CF3SO3)8.2CF3SO3H.5MeOH (7) by reacting (cyclen)Ru(CF3SO3)3 with 4,4'-bpy in methanol. The crystal structure of 4.11H2O reveals an equilateral triangle in which the 4,4'-bpy bridges are bowed outward, such that the pyridine rings are all forced to be perpendicular to the Ru3 triangle. Consequently, adjacent pyridine rings are essentially coplanar, and the cyclic voltammogram of [(cyclen)3Ru3(4,4'-bpy)3]6+ in acetonitrile displays three distinct one-electron oxidation events. Cyclic voltammetry measurements reveal redox processes centered at E(1/2) = 0.207, 0.342, and 0.434 V versus Cp2Fe(0/+) that are assigned to 6+/7+, 7+/8+, and 8+/9+ couples of the [(cyclen)3Ru3(4,4'-bpy)3]n+ triangle, respectively. In contrast, the structure of [(cyclen)4Ru4(4,4'-bpy)4]8+ features a regular square geometry wherein the rings of the bridging 4,4'-bpy ligands are free to rotate, leading to just one four-electron oxidation couple centered at 0.430 V. Density functional theory calculations performed on [(cyclen)3Ru3(4,4'-bpy)(3)]6+ reveal metal-based orbitals with contributions from the pi system of the bridging 4,4'-bpy ligands, providing a likely pathway for electron transfer.

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Section: Resultsmentioning

confidence: 61%

Section: Introductionmentioning

confidence: 99%

Angle-Dependent Electronic Effects in 4,4‘-Bipyridine-Bridged Ru₃ Triangle and Ru₄ Square Complexes

et al. 2006

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“…31−37 This chromophore has been incorporated into polymers 38−41 and metal−organic frameworks. 42−47 While ruthenium−pyridyl bonding has been used to form a variety of metallacycles and cages, the auxiliary ligands that fill the ruthenium coordination sphere, such as phosphines, 48 cyclens, 49 crown sulfurs, 50 and the popular ruthenium arene clips, 51 have rendered tecton photophysically uninteresting. Moreover, the use of ruthenium−polypyridyl bonding as the driver for assembly, as opposed to other more well-known motifs, requires nontrivial work based on different metal− ligand bond kinetics and thermodynamics, solubilities and the general photoinstability of the ruthenium−pyridyl bond.…”

Section: ■ Introductionmentioning

confidence: 99%

“…We now extend our exploration of the coordination-driven self-assembly of phosphorescent molecules to ruthenium polypyridyl chemistry, a currently undeveloped node in self-assembly. The [Ru(bpy) 3 ] 2+ cation (bpy = 2,2′-bipyridine) and its analogues have a rich history as agents for light harvesting. − This chromophore has been incorporated into polymers − and metal–organic frameworks. − While ruthenium–pyridyl bonding has been used to form a variety of metallacycles and cages, the auxiliary ligands that fill the ruthenium coordination sphere, such as phosphines, cyclens, crown sulfurs, and the popular ruthenium arene clips, have rendered tecton photophysically uninteresting. Moreover, the use of ruthenium–polypyridyl bonding as the driver for assembly, as opposed to other more well-known motifs, requires nontrivial work based on different metal–ligand bond kinetics and thermodynamics, solubilities and the general photoinstability of the ruthenium–pyridyl bond.…”

Section: Introductionmentioning

confidence: 99%

Coordination-Driven Self-Assembly of Ruthenium Polypyridyl Nodes Resulting in Emergent Photophysical and Electrochemical Properties

et al. 2017

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Ruthenium polypyridyl complexes are among the most studied molecular species for photochemical applications such as light-harvesting and photocatalysis, with [Ru(bpy)] (bpy = 2,2'-bipyridine) serving as an iconic example. We report the use of the [Ru(bpy)] fragment as a 90° acceptor tecton (M) in coordination-driven self-assembly to synthesize a ML metallacycle (L = 4,4'-bipyridine) and a ML truncated tetrahedral cage [L = 2,4,6-tris(4-pyridyl)-1,3,5-triazine]. The ML cage possesses emergent properties attributed to its unique electronic structure, which results in increased visible-light absorption and an emission band that decays biexponentially with times of 3 and 790 ns. The presence of multiple ruthenium centers in the cage results in multiple Ru reduction events, with a cathodic shift of the first reduction relative to that of [Ru(bpy)]Cl (0.56 V vs 1.05 V). The ligand-centered reduction shifts anodically (-1.29 vs -1.64 V) versus the first bpy reduction observed in the parent [Ru(bpy)]Cl. The photophysical properties are explained by the existence of two localized charge-transfer states in the cage molecule: one that draws upon the bipyridine π* orbitals and the other upon the 2,4,6-tris(4-pyridyl)-1,3,5-triazine π* orbitals.

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“…33,34 The 3-3´ peaks could be attributed to the [RuCl 2 (dppb)(4,4'-bipy) 2 ] mononuclear complex and to the tetramer complex [RuCl 2 (dppb)(µ-4,4'-bipy)] 4 . The tetramer complex was isolated chemically by Queiroz et al 38 …”

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confidence: 99%

A novel binuclear ruthenium complex: spectroscopic and electrochemical characterization, and formation of Langmuir and Langmuir-Blodgett films

Wohnrath

Santos

Sandrino

et al. 2006

J. Braz. Chem. Soc.

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O complexo [{RuCl 3 (dppb)} 2 (µ-4,4'-bipy)] (dppb = PPh 2 (CH 2 ) 4 PPh 2 ; 4,4'-bipy= 4,4'-bipiridil) foi obtido por meio da reação entre 4,4'-bipiridina e mer- [RuCl 3 (dppb)] . H 2 O, em bom rendimento. As características do complexo binuclear obtido, estudadas por medidas de FT-IR, UV-Vis, EPR e análise elementar foram similares às do complexo [RuCl 3 (dppb)L] (L= N-heterociclo).[{RuCl 3 (dppb)} 2 (µ-4,4'-bipy)] é solúvel em solventes fracamente polares, facilitando a sua utilização para produzir filmes de Langmuir e Langmuir-Blodgett (LB). Enquanto que filmes cast e o complexo em solução são vermelhos, filmes LB são azul-esverdeados, provavelmente devido à oxidação da bisfosfina. A natureza nanoestruturada dos filmes LB, se manifestou nas medidas eletroquímicas, já que estes filmes exibem maior corrente de pico do que os filmes cast e dipcoated. As respostas eletroquímicas destes filmes são caracterizadas pelo processo Ru [{RuCl 3 (dppb)} 2 (µ-4,4'-bipy)] was prepared from the reaction of the 4,4'-bipyridine and mer-[RuCl 3 (dppb)] . H 2 O, in good yield. The characteristics of the binuclear complex studied with FT-IR, UV-Vis, EPR and elemental analysis were similar to those of the [RuCl 3 (dppb)L] (L= Nheterocycle). [{RuCl 3 (dppb)} 2 (µ-4,4'-bipy)] is soluble in weakly polar organic solvents, facilitating its use in the production of Langmuir and Langmuir-Blodgett (LB) films production. While the cast films and the complex in solution were red, the LB films were green-bluish, probably due to oxidation of the bisphosphine. The nanostructured nature of the LB films was manifested in electrochemical measurements, as these films exhibited higher peak currents than cast or dipcoated films. For all films, the electrochemical response was dominated by the Ru III Ru III /Ru II Ru II process, which differed from that of the binuclear compound. For the latter, an irreversible process appeared due to formation of new species. The electroactivity of LB films from [{RuCl 3 (dppb)} 2 (µ-4,4'-bipy)] also pointed to their possible use in electrochemical devices.

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Synthesis, Structural, Spectroscopic and Electrochemical Characterization of New Ruthenium(II) Tetramer Complexes Containing 1,4-Bis(diphenylphosphine)butane and Alterdentate Ligands

Cited by 6 publications

References 27 publications

Angle-Dependent Electronic Effects in 4,4‘-Bipyridine-Bridged Ru₃ Triangle and Ru₄ Square Complexes

Angle-Dependent Electronic Effects in 4,4‘-Bipyridine-Bridged Ru₃ Triangle and Ru₄ Square Complexes

Coordination-Driven Self-Assembly of Ruthenium Polypyridyl Nodes Resulting in Emergent Photophysical and Electrochemical Properties

A novel binuclear ruthenium complex: spectroscopic and electrochemical characterization, and formation of Langmuir and Langmuir-Blodgett films

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Synthesis, Structural, Spectroscopic and Electrochemical Characterization of New Ruthenium(II) Tetramer Complexes Containing 1,4-Bis(diphenylphosphine)butane and Alterdentate Ligands

Cited by 6 publications

References 27 publications

Angle-Dependent Electronic Effects in 4,4‘-Bipyridine-Bridged Ru3 Triangle and Ru4 Square Complexes

Angle-Dependent Electronic Effects in 4,4‘-Bipyridine-Bridged Ru3 Triangle and Ru4 Square Complexes

Coordination-Driven Self-Assembly of Ruthenium Polypyridyl Nodes Resulting in Emergent Photophysical and Electrochemical Properties

A novel binuclear ruthenium complex: spectroscopic and electrochemical characterization, and formation of Langmuir and Langmuir-Blodgett films

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Angle-Dependent Electronic Effects in 4,4‘-Bipyridine-Bridged Ru₃ Triangle and Ru₄ Square Complexes

Angle-Dependent Electronic Effects in 4,4‘-Bipyridine-Bridged Ru₃ Triangle and Ru₄ Square Complexes