Synthesis of Paramagnetic Tetranuclear Rhodium and Iridium Complexes with the 2,6-Pyridinedithiolate Ligand. Redox-Induced Degradation to Diamagnetic Triiridium Compounds

Pérez‐Torrente, Jesús J.; López, José A.; Ciriano, Miguel A.; Alonso, Pablo J.; Lahoz, Fernando J.; Oro, Luis A.

doi:10.1021/ic001349q

Cited by 14 publications

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“…Despite that, for steric reasons, 6-methylpyridyl donors are weaker donors than pyridine donors,11d 1e oxidation of Me 3 tpa complex 1 + is more easy than 1e oxidation of Me 2 tpa complex 2 + . This is probably related to the fact that, with increasing n, the increasing steric bulk of the Me n tpa ligands forces the geometry of the monocationic [(Me n tpa)Ir I (ethene)] + complexes to be closer to the preferred square pyramidal geometry of the dicationic Ir II oxidized species (see Table ).…”

Section: Resultsmentioning

confidence: 98%

“…Most of these examples concern olefin complexes of low-spin Co, Rh, and Ir metallo-radical species in the formal oxidation states 0 or +II. Only a few stable open-shell olefin complexes of the Co-triad are known. 5h,10c,, The above reactive ones could not be isolated, and their ligand centered radical behavior could only be inferred from the reaction products from in situ generated species. To our knowledge, only one stable mononuclear Ir II −olefin complex has been reported, viz.…”

Section: Introductionmentioning

confidence: 99%

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Ir^II(ethene): Metal or Carbon Radical?

et al. 2005

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One-electron oxidation of [(Me(n)tpa)Ir(I)(ethene)]+ complexes (Me(3)tpa = N,N,N-tri(6-methyl-2-pyridylmethyl)amine; Me(2)tpa = N-(2-pyridylmethyl)-N,N,-di[(6-methyl-2-pyridyl)methyl]-amine) results in relatively stable, five-coordinate Ir(II)-olefin species [(Me(n)tpa)Ir(II)(ethene)](2+) (1(2+): n = 3; 2(2+): n = 2). These contain a "vacant site" at iridium and a "non-innocent" ethene fragment, allowing radical type addition reactions at both the metal and the ethene ligand. The balance between metal- and ligand-centered radical behavior is influenced by the donor capacity of the solvent. In weakly coordinating solvents, 1(2+) and 2(2+) behave as moderately reactive metallo-radicals. Radical coupling of 1(2+) with NO in acetone occurs at the metal, resulting in dissociation of ethene and formation of the stable nitrosyl complex [(Me(3)tpa)Ir(NO)](2+) (6(2+)). In the coordinating solvent MeCN, 1(2+) generates more reactive radicals; [(Me(3)tpa)Ir(MeCN)(ethene)](2+) (9(2+)) by MeCN coordination, and [(Me(3)tpa)Ir(II)(MeCN)](2+) (10(2+)) by substitution of MeCN for ethene. Complex 10(2+) is a metallo-radical, like 1(2+) but more reactive. DFT calculations indicate that 9(2+) is intermediate between the slipped-olefin Ir(II)(CH(2)=CH(2)) and ethyl radical Ir(III)-CH(2)-CH(2). resonance structures, of which the latter prevails. The ethyl radical character of 9(2+) allows radical type addition reactions at the ethene ligand. Complex 2(2+) behaves similarly in MeCN. In the absence of further reagents, 1(2+) and 2(2+) convert to the ethylene bridged species [(Me(n)tpa)(MeCN)Ir(III)(mu(2)-C(2)H(4))Ir(III)(MeCN)(Me(3)tpa)](4+) (n = 3: 3(4+); n = 2: 4(4+)) in MeCN. In the presence of TEMPO (2,2,6,6-tetramethyl-1-piperidinyloxo), formation of 3(4+) from 1(2+) in MeCN is completely suppressed and only [(Me(3)tpa)Ir(III)(TEMPO(-))(MeCN)](2+) (7(2+)) is formed. This is thought to proceed via radical coupling of TEMPO at the metal center of 10(2+). In the presence of water, hydrolysis of the coordinated acetonitrile fragment of 7(2+) results in the acetamido complex [(Me(3)tpa)Ir(III)(NHC(O)CH(3)))(TEMPOH)](2+) (8(2+)).

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Section: Resultsmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Ir^II(ethene): Metal or Carbon Radical?

et al. 2005

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“…Examples are the wire-like tri-and tetranuclear Rh and Ir compounds of the type [Rh 3 (µ 3 -L) 2 (CO) 2 (η 4 -cod) 2 ] 2+ , [9] [Rh 2 Ir(µ 3 -OMe 2 napy) 2 (CO) 2 (cod) 2 ] 2+ , [10] and [M 4 (µ-PyS 2 ) 2 (bis-alkene) 4 ] + (M = Rh, Ir). [11] These "molecular wires" have the unpaired electron delocalized over multiple metal centers, suggestive of potential conducting properties of such wires. The delocalization of the unpaired spin density contributes to the relative stability of these species.…”

Section: Spin Delocalization Over Multiple Metal Atomsmentioning

confidence: 99%

Paramagnetic (Alkene)Rh and (Alkene)Ir Complexes: Metal or Ligand Radicals?

Bruin

Hetterscheid

2007

Eur J Inorg Chem

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Keywords: Rhodium / Iridium / Alkene ligands / Metallo-radicals / Ligand radicals In this review a detailed overview is given of the (electronic) structure and reactivity of open-shell (paramagnetic) alkene rhodium and iridium complexes M x (alkene) (M = Rh, Ir; x = 0, +II). In most cases these species are highly reactive, but some notable exceptions of stable species for which not much reactivity has been described are also included (section 2). coupling reactions with a series of other radicals, as well as metal-based allylic hydrogen atom abstractions from M II (α-alkene) species. On the other hand, (donor induced) ligand radical character is crucial in a variety of M-C and C-C radical coupling reactions, C-O bond formation by oxygenation of M II (alkene) species and alkene "insertions" into (por)M-H bonds. The review concludes with some speculations about possible roles of paramagnetic M(olefin) (M = Rh, Ir) species in catalytic olefin oxygenation and carbene transfer reactions.

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“…10 The rhodium and iridium tetranuclear complexes [M 4 ] are redox-active precursors of mixed-valence paramagnetic [M 4 ] + complexes. 11 They also behave as encapsulating agents for the thallium(I) ion to give the cationic pentametallic species [TlM 4 (µ-PyS 2 ) 2 (diolefin) 4 ] + through a great change of the coordination mode of the bridging 2,6-dimercaptopyridine ligands and the formation of two Tl-M bonds. 12 A preliminary test on the capability of the tetranuclear [Rh 4 (µ-PyS 2 ) 2 (cod) 4 ] complex to act as a metalloligand, due to the presence of two available coordination donor sites at the peripheral sulfur atoms, has lead to the synthesis of the polymer [ClCuRh 4 (µ-PyS 2 ) 2 (cod) 4 ] n (cod =1,5-cyclooctadiene) fully characterized by a crystal structure determination.…”

Section: Introductionmentioning

confidence: 99%

“…Cu(CH 3 CN) 4 ]BF 4 resulted in the formation of the coordination assemblies [CuRh 4 (µ-PyS 2 ) 2 (cod) 4 ] n[BF 4 ] n(10) and [CuRh 4 (µ-PyS 2 ) 2 (tfbb) 4 ] n[BF 4 ] n(11) in good isolated yields.The formation of the silver(I) complexes 8 and 9 competes with the oxidation of the corresponding rhodium tetranuclear complexes. In fact, complex 8 decomposes slowly in dichloromethane to give the paramagnetic compound [Rh 4 (µ-PyS 2 ) 2 (cod) 4 ]BF 4 and metallic silver.…”

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Tetranuclear [Rh₄(μ-PyS₂)₂(diolefin)₄] Complexes as Building Blocks for New Inorganic Architectures: Synthesis of Coordination Polymers and Heteropolynuclear Complexes with Electrophilic d⁸and d¹⁰Metal Fragments

et al. 2004

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The reaction of [Rh4(mu-PyS2)2(cod)4] (PyS2 = 2,6-pyridinedithiolate, cod = 1,5-cyclooctadiene) with CF3SO3Me gave the cationic complex [Rh(4)(mu-PyS(2)Me)(2)(cod)4][CF3SO3]2 (1) with two 6-(thiomethyl)pyridine-2-thiolate bridging ligands from the attack of Me+ at the terminal sulfur atoms of the starting material. Under identical conditions [Rh4(mu-PyS2)2(tfbb)4] (tfbb = tetrafluorobenzobarrelene) reacted with CF3SO3Me to give the mixed-ligand complex [Rh(4)(mu-PyS2)(mu-PyS2Me)(tfbb)4][CF3SO3] 2. The nucleophilicity of the bridging ligands in the complexes [Rh4(mu-PyS2)2(diolefin)4] was exploited to prepare heteropolynuclear species. Reactions with [Au(PPh3)(Me2CO)][ClO4] gave the hexanuclear complexes [(PPh3)2Au2Rh4(mu-PyS2)2(diolefin)4][ClO4]2 (diolefin = cod (3), tfbb (4)). The structure of 4, solved by X-ray diffraction methods, showed the coordination of the [Au(PPh3)]+ fragments to the peripheral sulfur atoms in [Rh4(mu-PyS2)2(diolefin)4] along with their interaction with the neighbor rhodium atoms. Neutral coordination polymers of formula [ClMRh4(mu-PyS2)2(diolefin)4]n (M = Cu (5, 6), Au (7)) result from the self-assembly of alternating [Rh4(mu-PyS2)2(diolefin)4] ([Rh4]) blocks and MCl linkers. The formation of the infinite polymetallic chains was found to be chiroselective for M = Cu; one particular chain contains exclusively homochiral [Rh4] complexes. Cationic heterometallic coordination polymers of formula [MRh4(mu-PyS2)2(diolefin)4]n[BF4]n (M = Ag (8, 9), Cu (10, 11)) and [Rh5(mu-PyS2)2(diolefin)5]n[BF4]n (12, 13) result from the reactions of [Rh4] with [Cu(CH2CN)4]BF4, AgBF4, and [Rh(diolefin)(Me2CO)2]BF4, respectively. The heterometallic coordination polymers exhibit a weak electric conductivity in the solid state in the range (1.2-2.8) x 10(-7) S cm(-1).

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Synthesis of Paramagnetic Tetranuclear Rhodium and Iridium Complexes with the 2,6-Pyridinedithiolate Ligand. Redox-Induced Degradation to Diamagnetic Triiridium Compounds

Abstract: The tetranuclear complexes [M 4 (4)

Cited by 14 publications

References 61 publications

Ir^II(ethene): Metal or Carbon Radical?

Ir^II(ethene): Metal or Carbon Radical?

Paramagnetic (Alkene)Rh and (Alkene)Ir Complexes: Metal or Ligand Radicals?

Tetranuclear [Rh₄(μ-PyS₂)₂(diolefin)₄] Complexes as Building Blocks for New Inorganic Architectures: Synthesis of Coordination Polymers and Heteropolynuclear Complexes with Electrophilic d⁸and d¹⁰Metal Fragments

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Synthesis of Paramagnetic Tetranuclear Rhodium and Iridium Complexes with the 2,6-Pyridinedithiolate Ligand. Redox-Induced Degradation to Diamagnetic Triiridium Compounds

Abstract: The tetranuclear complexes [M 4 (4)

Cited by 14 publications

References 61 publications

IrII(ethene): Metal or Carbon Radical?

IrII(ethene): Metal or Carbon Radical?

Paramagnetic (Alkene)Rh and (Alkene)Ir Complexes: Metal or Ligand Radicals?

Tetranuclear [Rh4(μ-PyS2)2(diolefin)4] Complexes as Building Blocks for New Inorganic Architectures: Synthesis of Coordination Polymers and Heteropolynuclear Complexes with Electrophilic d8and d10Metal Fragments

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Ir^II(ethene): Metal or Carbon Radical?

Ir^II(ethene): Metal or Carbon Radical?

Tetranuclear [Rh₄(μ-PyS₂)₂(diolefin)₄] Complexes as Building Blocks for New Inorganic Architectures: Synthesis of Coordination Polymers and Heteropolynuclear Complexes with Electrophilic d⁸and d¹⁰Metal Fragments