π Back-Bonding of Iron(II) Complexes Supported by Tris(pyrid-2-ylmethyl)amine and Its Nitro-Substituted Derivatives

Furukawa, Shinya; Hitomi, Yutaka; Shishido, Tetsuya; Teramura, Kentaro; Tanaka, Tsunehiro

doi:10.1021/jp2069539

Cited by 5 publications

(5 citation statements)

References 41 publications

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“…Note that the latter conclusions are true under the experimental conditions of X‐ray diffraction, that is, at 100 K. A comparison of the Fe–N py bond lengths of 1 ‐(CH 3 CN) 2 and 2 ‐(CH 3 CN) 2 shows that those of 1 ‐(CH 3 CN) 2 are slightly shorter, which is consistent with a higher π‐accepting character of the 4‐nitropyridine ring with respect to the 4‐unsubstituted one. Similarly, Furukawa et al showed that the Fe–N py bond lengths in Fe II –TPA‐type [TPA = tris(pyrid‐2‐ylmethyl)amine] complexes become shorter if NO 2 groups are introduced at the para positions of the pyridine rings . They rationalized these observations on the basis of stronger π‐backbonding interactions between the Fe t 2g orbitals and the π* orbitals of 4‐nitropyridine compared with those for the unsubstituted ones.…”

Section: Resultsmentioning

confidence: 93%

“…Similarly, Furukawa et al showed that the Fe-N py bond lengths in Fe II -TPA-type [TPA = tris(pyrid-2-ylmethyl)amine] complexes become shorter if NO 2 groups are introduced at the para positions of the pyridine rings. [32] They rationalized these observations on the basis of stronger π-backbonding interactions between the Fe t 2g orbitals and the π* orbitals of 4-nitropyridine compared with those for the unsubstituted ones. The…”

Section: Synthesis and Solid-state Characterization Of Fe II Complexesmentioning

confidence: 85%

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Synthesis and Characterization of Iron(II) Complexes with a BPMEN‐Type Ligand Bearing π‐Accepting Nitro Groups

et al. 2017

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In this paper, we describe the synthesis, characterization, and stability studies of new FeII complexes prepared with the ligand N,N′‐dimethyl‐N,N′‐bis(4‐nitropyridin‐2‐ylmethyl)ethane‐1,2‐diamine (L42NO2). The properties of these complexes were probed by magnetic, spectroscopic, and electrochemical techniques and compared with those of the parent complexes prepared with the unsubstituted ligand N,N′‐dimethyl‐N,N′‐bis(pyridin‐2‐ylmethyl)ethane‐1,2‐diamine (BPMEN or L42). The para functionalization of the pyridine moieties with π‐accepting nitro groups increases the ligand‐field strength and the Lewis acidity of the metal center without altering the stability of the complex.

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Section: Resultsmentioning

confidence: 93%

Section: Synthesis and Solid-state Characterization Of Fe II Complexesmentioning

confidence: 85%

Synthesis and Characterization of Iron(II) Complexes with a BPMEN‐Type Ligand Bearing π‐Accepting Nitro Groups

et al. 2017

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“…Due to the redox accessibility of iron, the Fe 3 O cluster has been noted to undergo reduction events in both MOFs, ,− producing a mixed valent μ 3 -oxo Fe(III) 2 Fe(II) cluster under a high-temperature (∼220 °C) thermal treatment. This mixed valent state is particularly important for the adsorption of certain unsaturated molecules, such as alkenes and alkynes, as the Fe(II) sites have improved π-backdonation capabilities compared to the Fe(III) centers. , This improved backdonation allows for a higher adsorption enthalpy at these open metal sites, thus leading to an improvement in adsorption capacity, particularly at the low adsorption pressures …”

Section: Introductionmentioning

confidence: 99%

“…This mixed valent state is particularly important for the adsorption of certain unsaturated molecules, such as alkenes and alkynes, as the Fe(II) sites have improved π-backdonation capabilities compared to the Fe(III) centers. 28,31 This improved backdonation allows for a higher adsorption enthalpy at these open metal sites, thus leading to an improvement in adsorption capacity, particularly at the low adsorption pressures. 32 These two MOFs are well known for their gas separation performance; MIL-100 has been shown to have a high affinity toward hydrocarbons such as propane.…”

Section: ■ Introductionmentioning

confidence: 99%

Evaluation of Iron-Based Metal–Organic Framework Activation Temperatures in Acetylene Adsorption

Day¹,

Rowe

Ybanez³

et al. 2022

Inorg. Chem.

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One of the major issues regarding long-term human space exploration is the need for a breathable atmosphere. A major component toward achieving this goal is both the removal of exhaled carbon dioxide (CO2) and the generation or recovery of oxygen (O2). NASA’s current technology only operates at about 50% efficiency due to the need to vent the methane that is produced during the CO2 reduction process. One method of improving the efficiency of this process is through plasma pyrolysis, wherein the methane is pyrolyzed to produce hydrogen and various dehydrogenated carbon byproducts. In this process, acetylene is one of the main components of this byproduct stream. Unfortunately, while the concentration of this effluent is generally high in hydrogen (>90% typically), the presence of the acetylene waste product can act as a poison for the ruthenium–alumina catalyst used in the CO2-reducing Sabatier process, requiring a removal step. Metal–organic frameworks (MOFs) represent a valuable method for removing these unsaturated hydrocarbons due to their high tunability, particularly through the incorporation of open metal sites. In this study, two common iron-based MOFs, MIL-100 and PCN-250, were studied for their ability to adsorb acetylene. A combination of gas adsorption analysis and density functional theory calculation results shows the ability of these materials to undergo a thermal-induced reduction event, which results in an improvement in gas adsorption performance. This improvement in gas performance appears to be at least partially due to the increased presence of π-backbonding toward the acetylene molecules.

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“…This mixed valent state is particularly important for the adsorption of certain unsaturated molecules, such as alkenes and alkynes, as the Fe(II) sites have improved π-backdonation capabilities compared to the Fe(III) centers. 28,31 This improved backdonation allows for a higher adsorption enthalpy at these open metal sites, thus leading to an improvement in adsorption capacity, particularly at the low adsorption pressures. 32 For this project the two MOFs, MIL-100 and PCN-250 were analyzed for their gas adsorption performance towards the byproducts of methane pyrolysis, with an evaluation of activation temperature showed a remarkable improvement in gas uptake, due to the production of the mixed valent states within the MOFs.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of Iron-Based Metal-Organic Framework Activation Temperature in Acetylene Adsorption

Day¹,

Rowe

Ybanez³

et al. 2022

Preprint

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One of the major issues regarding long-term human space exploration is the need for a breathable atmosphere. Typically, this requires both removal of exhaled CO2 and generation or recovery of oxygen. NASA’s current technology only operates at about 50% efficiency due to the need to vent methane that is produced during the CO2 reduction process. One method of improving the efficiency of this process is through plasma pyrolysis, wherein the methane is pyrolyzed to produce hydrogen and various dehydrogenated carbon byproducts, with acetylene being one of the main components of this byproduct stream. Unfortunately, while the concentration of this effluent is generally high in hydrogen (>90% typically) the presence of this acetylene can act as a poison for the Sabatier catalysts, requiring a removal step. Metal-organic frameworks (MOFs) represent a valuable method removing these unsaturated hydrocarbons due to their high tunability, particularly through the incorporation of open metal sites. In this study, two common iron-based MOFs, MIL-100 and PCN-250, were studied for their ability to adsorb acetylene. A combination of gas adsorption and density functional theory results show the ability of these materials to undergo a thermal induced reduction event results in an improvement in gas adsorption performance, which appears to be at least partially due to the increased presence of π-backbonding towards the acetylene molecules.

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π Back-Bonding of Iron(II) Complexes Supported by Tris(pyrid-2-ylmethyl)amine and Its Nitro-Substituted Derivatives

Cited by 5 publications

References 41 publications

Synthesis and Characterization of Iron(II) Complexes with a BPMEN‐Type Ligand Bearing π‐Accepting Nitro Groups

Synthesis and Characterization of Iron(II) Complexes with a BPMEN‐Type Ligand Bearing π‐Accepting Nitro Groups

Evaluation of Iron-Based Metal–Organic Framework Activation Temperatures in Acetylene Adsorption

Evaluation of Iron-Based Metal-Organic Framework Activation Temperature in Acetylene Adsorption

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