Synthesis and Reactivity of Nonbridged Metal−Metal Bonded Rhodium and Iridium Phenanthroline-Based N<sub>2</sub>O<sub>2</sub> Dimers

Feng, Maoqi; Chan, Kin Shing

doi:10.1021/om010903g

Cited by 32 publications

(30 citation statements)

References 47 publications

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“…Despite previous evidence to the contrary, we were able to prepare L1–L4 in moderate yields using standard Suzuki coupling conditions, with 5,6-dibromo-1,10-phenanthroline and the respective boronic acid combined with palladium tetrakis-triphenylphosphine in a biphasic mixture of toluene and aqueous base (sodium carbonate or potassium hydroxide), as outlined in Scheme . After the reaction was complete, the product was extracted into chloroform, evaporated under reduced pressure, and purified either by column chromatography, to give L1 (55%) and L4 (62%) or recrystallization to give L2 (37%) and L3 (75%).…”

Section: Resultsmentioning

confidence: 84%

Accessing a Long-Lived ³LC State in a Ruthenium(II) Phenanthroline Complex with Appended Aromatic Groups

et al. 2020

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The photophysical properties of a series of heteroleptic Ru(II) complexes of the form [Ru(phen) 2 (phen-5,6-R 2 )] 2+ , where phen = 1,10-phenanthroline and R = phenyl (Ph), p-tert-butylbenzene (p-Ph-tBu), p-methoxybenzene (p-Ph-OMe), and 2-naphthalene (2-naph), have been measured. Variation of the R group does not greatly perturb the electronic properties of the ground state, which were explored with electronic absorption and resonance Raman spectroscopy and are akin to those of the archetypal parent complex [Ru(phen) 3 ] 2+ . All complexes were shown to possess emissive 3 MLCT states, characterized through transient absorption and emission spectroscopy. However, an additional, long-lived excited state was observed in the Ru(II) naphthalene complex. The naphthalene substituents facilitate population of a 40 μs dark state which decays independently to that of the emissive 3 MLCT state. This state was characterized as 3 LC in nature, delocalized over the naphthalene substituted ligand.

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Section: Resultsmentioning

confidence: 84%

Accessing a Long-Lived ³LC State in a Ruthenium(II) Phenanthroline Complex with Appended Aromatic Groups

et al. 2020

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“…The previous examples were synthesized by the dimerization of reactive Ir II metalloradicals (formed via abstraction of H • from an Ir III −H, 41 or by oxidation of an Ir I ). 40 Some Ir II −Ir II dimers are known to uptake H 2 , generating 2 equiv of the corresponding Ir III −H, 46,47 but they are rarely made by this kind of dinuclear reductive elimination. 48 The dinuclear reductive elimination reaction from [1-MH• t BuPy] + was monitored over time by 1 H NMR spectroscopy in acetone-d 6 .…”

Section: ■ Resultsmentioning

confidence: 99%

“…Ir II dimers, especially ones where the M–M bond is not further supported by a bridging ligand, are often described as “unusual” or “rare.” The previous examples were synthesized by the dimerization of reactive Ir II metalloradicals (formed via abstraction of H • from an Ir III –H, or by oxidation of an Ir I ) . Some Ir II –Ir II dimers are known to uptake H 2 , generating 2 equiv of the corresponding Ir III –H, , but they are rarely made by this kind of dinuclear reductive elimination …”

Section: Resultsmentioning

confidence: 99%

Metal/Ligand Proton Tautomerism Facilitates Dinuclear H₂Reductive Elimination

Kuo

Goldberg

2020

J. Am. Chem. Soc.

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Using the doubly protic bis-pyrazole-pyridine ligand (N(NNH)2), we have synthesized an octahedral IrIII–H [HIr(κ3-N(NNH)(NN–))(CO)( t BuPy)]+ ([1-MH]+) from an IrI starting material. This hydride was generated by adding sufficient electron density to the metal center such that it became the thermodynamically preferred site of protonation. It was observed via UV–vis spectroscopy that [1-MH]+ establishes a [ t BuPy] dependent equilibrium with a ligand protonated square-planar IrI [Ir(N(NNH)2)(CO)]+ ([2-LH]+). This example of metal/ligand proton tautomerism is unusual in that the position of the equilibrium can be controlled by the concentration of exogeneous ligand (i.e., t BuPy). This equilibrium was shown to be key to the reactivity of the IrIII–H; 2 equiv of [1-MH]+ release H2, converting to the IrII dimer [[Ir(N(NN–)(NNH))(CO)( t BuPy)]2]2+ ([7]2+) under mild conditions (observable at room temperature). Mechanistic evidence is presented to support that this dinuclear reductive elimination occurs by tautomerization of the metal hydride [1-MH]+ to a ligand protonated species [1-LH]+, from which ligand dissociation is facile, generating [2-LH]+. Subsequent reaction of [2-LH]+ with [1-MH]+ allows for production of H2 and the IrII dimer [7]2+. The tautomerization between the metal-hydride and the ligand protonated species provides a low energy pathway for ligand dissociation, opening the needed coordination site. The ability to control the interconversion between a metal-hydride and a ligand-protonated congener using an exogeneous ligand introduces a new strategy for catalyst design with proton responsive ligands.

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“…General Comments: [Cu(NCMe) 4 ](PF 6 ), 2, 2′‐bipyridine (bpy),1, 10‐phenanthroline (phen), and 5, 6‐dimethyl‐1, 10‐phenanthroline(dmp) were purchased from Aldrich Chemicals. [Cu(NCMe) 4 ](BF 4 ),271, 4‐bis(diphenylphosphanyl)benzene,28 1, 3, 5‐tris(4‐diphenylphosphinophenyl)benzene,20 1, 4‐bis(dipyrrolylphosphanyl)benzene,29 4, 4′‐bis(diphenylphosphanyl)biphenyl,28 and 5, 6‐dibromo‐1, 10‐phenanthroline (phenBr 2 ),30 were synthesized according to published procedures. Preparation of the phosphines and all reactions with Cu + ion were carried out in an argon atmosphere using standard Schlenk techniques.…”

Section: Methodsmentioning

confidence: 99%

Synthesis and Biological Evaluation of Purine 2′‐Fluoro‐2′‐deoxyriboside ProTides as Anti‐influenza Virus Agents

et al. 2013

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2'-Fluoro-2'-deoxyguanosine has been reported to have potent anti-influenza virus activity in vitro and in vivo. Herein we describe the synthesis and biological evaluation of 6-modified 2'-fluoro-2'-deoxyguanosine analogues and their corresponding phosphoramidate ProTides as potential anti-influenza virus agents. Whereas the parent nucleosides were devoid of antiviral activity in two different cellular assays, the 5'-O-naphthyl(methoxy-L-alaninyl) ProTide derivatives of 6-O-methyl-2'-fluoro-2'-deoxyguanosine, 6-O-ethyl-2'-fluoro-2'-deoxyguanosine, and 2'-deoxy-2'-fluoro-6-chloroguanosine, and the 5'-O-naphthyl(ethoxy-L-alaninyl) ProTide of 6-O-ethyl-2'-fluoro-2'-deoxyguanosine displayed antiviral EC(99) values of ~12 μM. The antiviral results are supported by metabolism studies. Rapid conversion into the L-alaninyl metabolite and then 6-modified 2'-fluoro-2'-deoxyguanosine 5'-monophosphate was observed in enzymatic assays with yeast carboxypeptidase Y or crude cell lysate. Evidence for efficient removal of the 6-substituent on the guanine part was provided by enzymatic studies with adenosine deaminase, and by molecular modeling of the nucleoside 5'-monophosphates in the catalytic site of a model of ADAL1, thus indicating the utility of the double prodrug concept.

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Synthesis and Reactivity of Nonbridged Metal−Metal Bonded Rhodium and Iridium Phenanthroline-Based N₂O₂ Dimers

Cited by 32 publications

References 47 publications

Accessing a Long-Lived ³LC State in a Ruthenium(II) Phenanthroline Complex with Appended Aromatic Groups

Accessing a Long-Lived ³LC State in a Ruthenium(II) Phenanthroline Complex with Appended Aromatic Groups

Metal/Ligand Proton Tautomerism Facilitates Dinuclear H₂Reductive Elimination

Synthesis and Biological Evaluation of Purine 2′‐Fluoro‐2′‐deoxyriboside ProTides as Anti‐influenza Virus Agents

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Synthesis and Reactivity of Nonbridged Metal−Metal Bonded Rhodium and Iridium Phenanthroline-Based N2O2 Dimers

Cited by 32 publications

References 47 publications

Accessing a Long-Lived 3LC State in a Ruthenium(II) Phenanthroline Complex with Appended Aromatic Groups

Accessing a Long-Lived 3LC State in a Ruthenium(II) Phenanthroline Complex with Appended Aromatic Groups

Metal/Ligand Proton Tautomerism Facilitates Dinuclear H2Reductive Elimination

Synthesis and Biological Evaluation of Purine 2′‐Fluoro‐2′‐deoxyriboside ProTides as Anti‐influenza Virus Agents

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Synthesis and Reactivity of Nonbridged Metal−Metal Bonded Rhodium and Iridium Phenanthroline-Based N₂O₂ Dimers

Accessing a Long-Lived ³LC State in a Ruthenium(II) Phenanthroline Complex with Appended Aromatic Groups

Accessing a Long-Lived ³LC State in a Ruthenium(II) Phenanthroline Complex with Appended Aromatic Groups

Metal/Ligand Proton Tautomerism Facilitates Dinuclear H₂Reductive Elimination