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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.


Pseudotetrahedralgroup 9 imido complexes with low-spin ground states.16
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fig1: Pseudotetrahedralgroup 9 imido complexes with low-spin ground states.16

Mentions: Within group 9, pseudotetrahedral MIII (M = Co, Rh, Ir) imidos are best characterized and werereported from the groups of Bergman, Peters, Meyer, Theopold, Smith,and Tejel (Figure 1).16 Notably, complex E was not prepared with an azide precursorbut from the respective cobalt(II) amido complex upon HAA with the2,4,6-tri-tert-butylphenoxy radical. This reactionis consistent with a computed N–H bond dissociation enthalpyin the amido complex of 75 kcal mol–1.16g Hence, HAA from an unactivated hydrocarbonwill be thermochemically unfavorable. Complexes A–F exhibit two-electron, electrophilic imido group reactivity,such as NR transfer to phosphines, CO, or isocyanate, as expectedfrom their low-spin (S = 0) ground states. Interestingly,Theopold et al. (Figure 1, F)and Betley et al. (Scheme 3) reported Co imidocomplexes with thermally accessible open-shell states.16e,16f,17 In fact, these compounds alsoundergo radical-type nitrene group transfer upon intramolecular insertioninto benzylic C–H bonds (Scheme 3).


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)

Pseudotetrahedralgroup 9 imido complexes with low-spin ground states.16
© Copyright Policy
Related In: Results  -  Collection

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

fig1: Pseudotetrahedralgroup 9 imido complexes with low-spin ground states.16
Mentions: Within group 9, pseudotetrahedral MIII (M = Co, Rh, Ir) imidos are best characterized and werereported from the groups of Bergman, Peters, Meyer, Theopold, Smith,and Tejel (Figure 1).16 Notably, complex E was not prepared with an azide precursorbut from the respective cobalt(II) amido complex upon HAA with the2,4,6-tri-tert-butylphenoxy radical. This reactionis consistent with a computed N–H bond dissociation enthalpyin the amido complex of 75 kcal mol–1.16g Hence, HAA from an unactivated hydrocarbonwill be thermochemically unfavorable. Complexes A–F exhibit two-electron, electrophilic imido group reactivity,such as NR transfer to phosphines, CO, or isocyanate, as expectedfrom their low-spin (S = 0) ground states. Interestingly,Theopold et al. (Figure 1, F)and Betley et al. (Scheme 3) reported Co imidocomplexes with thermally accessible open-shell states.16e,16f,17 In fact, these compounds alsoundergo radical-type nitrene group transfer upon intramolecular insertioninto benzylic C–H bonds (Scheme 3).

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.