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Homolytic N-H activation of ammonia: hydrogen transfer of parent iridium ammine, amide, imide, and nitride species.

Scheibel MG, Abbenseth J, Kinauer M, Heinemann FW, Würtele C, de Bruin B, Schneider S - Inorg Chem (2015)

Bottom Line: The redox series [Ir(n)(NHx)(PNP)] (n = II-IV, x = 3-0; PNP = N(CHCHPtBu2)2) was examined with respect to electron, proton, and hydrogen atom transfer steps.The experimental and computational results suggest that the Ir(III) imido species [Ir(NH)(PNP)] is not stable but undergoes disproportionation to the respective Ir(II) amido and Ir(IV) nitrido species.N-H bond strengths are estimated upon reaction with hydrogen atom transfer reagents to rationalize this observation and are used to discuss the reactivity of these compounds toward E-H bond activation.

View Article: PubMed Central - PubMed

Affiliation: Institut für Anorganische Chemie, Georg-August-Universität , Tammannstraße 4, 37077 Göttingen, Germany.

ABSTRACT
The redox series [Ir(n)(NHx)(PNP)] (n = II-IV, x = 3-0; PNP = N(CHCHPtBu2)2) was examined with respect to electron, proton, and hydrogen atom transfer steps. The experimental and computational results suggest that the Ir(III) imido species [Ir(NH)(PNP)] is not stable but undergoes disproportionation to the respective Ir(II) amido and Ir(IV) nitrido species. N-H bond strengths are estimated upon reaction with hydrogen atom transfer reagents to rationalize this observation and are used to discuss the reactivity of these compounds toward E-H bond activation.

No MeSH data available.


Qualitative representation of the frontier orbitalinteractions within amide 6, imide 10 (onlytriplet state is shown), and nitride 3a.
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fig7: Qualitative representation of the frontier orbitalinteractions within amide 6, imide 10 (onlytriplet state is shown), and nitride 3a.

Mentions: These results can be rationalizedwith qualitative frontier MO considerations within the IrNHx redox series. The SOMO of the amido species 6 (Figure 7 left, π*) is mainlymetal centered (dxz) with some Ir–Namido π-antibonding contribution. HAA and formation ofimide 10 results in overlap of another nitrogen lone-pairwith an Ir d orbital (dxy), which is asubject of the Ir–N–H bond angle. The high degree ofcovalency within the two Ir–N orbital interactions with πsymmetry produces two high lying orbitals (Figure 7 center, π1* and π2*), whichare occupied with overall two electrons in the three accessible states(CSS, OSS, T). In comparison, the two Ir–N MOs with π*-characterin nitride 3a (Figure 7 right,π1* and π2*) are only occupied withoverall one electron. Hence, disproportionationof the IrIII-imide by intermolecular HAT to the IrII-amide and IrIV-nitride results in stabilizationupon both reduction of covalent Ir–N interactions (6) and reduction of the population of antibonding orbitals (3a), respectively.


Homolytic N-H activation of ammonia: hydrogen transfer of parent iridium ammine, amide, imide, and nitride species.

Scheibel MG, Abbenseth J, Kinauer M, Heinemann FW, Würtele C, de Bruin B, Schneider S - Inorg Chem (2015)

Qualitative representation of the frontier orbitalinteractions within amide 6, imide 10 (onlytriplet state is shown), and nitride 3a.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4597254&req=5

fig7: Qualitative representation of the frontier orbitalinteractions within amide 6, imide 10 (onlytriplet state is shown), and nitride 3a.
Mentions: These results can be rationalizedwith qualitative frontier MO considerations within the IrNHx redox series. The SOMO of the amido species 6 (Figure 7 left, π*) is mainlymetal centered (dxz) with some Ir–Namido π-antibonding contribution. HAA and formation ofimide 10 results in overlap of another nitrogen lone-pairwith an Ir d orbital (dxy), which is asubject of the Ir–N–H bond angle. The high degree ofcovalency within the two Ir–N orbital interactions with πsymmetry produces two high lying orbitals (Figure 7 center, π1* and π2*), whichare occupied with overall two electrons in the three accessible states(CSS, OSS, T). In comparison, the two Ir–N MOs with π*-characterin nitride 3a (Figure 7 right,π1* and π2*) are only occupied withoverall one electron. Hence, disproportionationof the IrIII-imide by intermolecular HAT to the IrII-amide and IrIV-nitride results in stabilizationupon both reduction of covalent Ir–N interactions (6) and reduction of the population of antibonding orbitals (3a), respectively.

Bottom Line: The redox series [Ir(n)(NHx)(PNP)] (n = II-IV, x = 3-0; PNP = N(CHCHPtBu2)2) was examined with respect to electron, proton, and hydrogen atom transfer steps.The experimental and computational results suggest that the Ir(III) imido species [Ir(NH)(PNP)] is not stable but undergoes disproportionation to the respective Ir(II) amido and Ir(IV) nitrido species.N-H bond strengths are estimated upon reaction with hydrogen atom transfer reagents to rationalize this observation and are used to discuss the reactivity of these compounds toward E-H bond activation.

View Article: PubMed Central - PubMed

Affiliation: Institut für Anorganische Chemie, Georg-August-Universität , Tammannstraße 4, 37077 Göttingen, Germany.

ABSTRACT
The redox series [Ir(n)(NHx)(PNP)] (n = II-IV, x = 3-0; PNP = N(CHCHPtBu2)2) was examined with respect to electron, proton, and hydrogen atom transfer steps. The experimental and computational results suggest that the Ir(III) imido species [Ir(NH)(PNP)] is not stable but undergoes disproportionation to the respective Ir(II) amido and Ir(IV) nitrido species. N-H bond strengths are estimated upon reaction with hydrogen atom transfer reagents to rationalize this observation and are used to discuss the reactivity of these compounds toward E-H bond activation.

No MeSH data available.