Oxidation of pentaamminecarbonylosmium(2+) to .mu.-dinitrogen-bis(cis-tetraamminecarbonylosmium)(4+)

BUHR, J. D.; Taube, Henry

doi:10.1021/ic50198a032

Cited by 64 publications

(24 citation statements)

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“…[Ru-NH 2 ] + + HC), and 88.6 kcal mol À1 ([Ru-NH 2 ] + ! [34] In the seminal work of Taube and co-workers, [35,36] as well as studies from Meyer and Huynh, [37] Os nitride coupling reactions were described. [Ru N] + + HC)was significantly lower (72.0 kcal mol À1 ), and HAA is thermodynamically favorable by 4.7 kcal mol À1 .ARu Vnitride is ap lausible product from the HAA reactions,a s some Ru Nc omplexes undergo spontaneous N···N bond formation via nitride coupling to form N 2 -bridged metal complexes or to liberate N 2 .…”

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confidence: 99%

Catalytic Ammonia Oxidation to Dinitrogen by Hydrogen Atom Abstraction

et al. 2019

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confidence: 99%

Catalytic Ammonia Oxidation to Dinitrogen by Hydrogen Atom Abstraction

et al. 2019

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“…The distribution of the photoproducts of I as obtained by analytical measurements suggests that the presence of an excess electron in Equation (1) causes complications. It is reasonable to assume that the primary photochemical step takes place according to Equation (2) because thermal [10,11] and photochemical [8,9] processes corresponding to the reverse reaction have been observed. The release of ammonia [Eq.…”

Section: Horst Kunkely and Arnd Vogler*mentioning

confidence: 99%

“…(1)].The expected photoproduct [Os(NH 3 ) 4 N] 3+ is also quite stable and well characterized. [7][8][9] In this context, it should be stressed that the reverse reaction has been observed as photochemical [8,9] and thermal [10,11] process. It is clearly easy to couple two nitride complexes containing the Os VI N j moiety to give a binuclear N 2 complex owing to the extreme stability of the resulting NÀN triple bond.The irradiation of I (absorption spectrum: [5] l max = 700 nm (e = 4000 m À1 cm À1 ) and 238 nm (e = 41 000) with a shoulder at 260 nm (e = 21 000)) results in a bleaching of the green color owing to the disappearance of the 700 nm absorption (Figure 1).…”

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confidence: 99%

Photolysis of Aqueous [(NH₃)₅Os(μ‐N₂)Os(NH₃)₅]⁵⁺: Cleavage of Dinitrogen by an Intramolecular Photoredox Reaction

Kunkely¹,

Vogler²

2010

Angew Chem Int Ed

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The lack of reactivity of dinitrogen which complicates its chemical conversion has been a challenge to chemists for many decades. [1,2] This difficulty is based on the extreme stability of the nitrogen-nitrogen triple bond. The huge energy difference between HOMO and LUMO (23 eV) makes N 2 rather redox inert. Moreover, the conversion of N 2 into simple species, such as ammonia or nitride, requires the transfer of six electrons. Such multi-electron transfer processes are generally associated with large activation barriers. Nevertheless, the reduction of N 2 to NH 3 occurs in nature through the utilization of the enzyme nitrogenase as catalyst. This conversion also takes place in the Haber-Bosch process, however, extreme conditions are required. Accordingly, it is of considerable interest to accomplish this reaction at ambient conditions. In principle, catalysis can be replaced by a photochemical procedure. The activation energy is then supplied by light. In favorable cases the photoactivation is selective and avoids interfering processes. Moreover, light may not only provide the activation energy but also the energy for an endothermic reaction which does not occur in catalysis at lower temperatures.In this context, it should be emphasized that some photochemical studies of binuclear N 2 -bridged complexes have been reported before. [3,4] However, in these cases N 2 is present in a reduced form containing a N À N double bond instead of a triple bond. This feature considerably facilitates the splitting of the N 2 ligand and may even take place thermally.[4] In contrast, the reductive splitting of the NÀN triple bond in a molecular complex is certainly much more difficult to achieve (see below), and has not yet been accomplished, neither thermally nor photochemically.Accordingly, we decided to examine a binuclear complex with a bridging N 2 ligand which largely preserves its integrity as a free dinitrogen molecule. This complex offers several attractive features. It is easily accessible and rather stable in aqueous solution in the absence of light. Owing to the intense color of I its disappearance can be precisely monitored. Although it is a mixed-valence system with considerable electronic delocalization between both metal centers, the triple bond of free N 2 is also present in the coordinated state as indicated by vibrational spectroscopy. Finally, the splitting of N 2 in the complex can be anticipated to proceed by a simple intramolecular redox reaction which produces only one excess electron that can lead to complications [Eq. (1)].The expected photoproduct [Os(NH 3 ) 4 N] 3+ is also quite stable and well characterized. [7][8][9] In this context, it should be stressed that the reverse reaction has been observed as photochemical [8,9] and thermal [10,11] process. It is clearly easy to couple two nitride complexes containing the Os VI N j moiety to give a binuclear N 2 complex owing to the extreme stability of the resulting NÀN triple bond.The irradiation of I (absorption spectrum: [5] l max = 700 nm (e = 4000 m ...

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“…A classical evolution for metal-ni-trido functions is the coupling that forms N 2 and reduced metals. [63][64][65][66][67][68][69][70] Ruthenium nitrido derivatives are not exempt from that fate. [36,71] In fact, our computational studies indicate that N 2 formation from 1 a is exothermic by 34.5 kcal mol À1 .…”

Section: Synthesismentioning

confidence: 99%

Vicinal Dinitridoruthenium‐Substituted Polyoxometalates γ‐[XW₁₀O₃₈{RuN}₂]⁶⁻ (X=Si or Ge)

Besson

Musaev

Lahootun

et al. 2009

Chemistry A European J

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Reaction of the divacant polyoxometalate K(8)[gamma-XW(10)O(36)] (X = Si, Ge) with two equivalents of the metal-nitrido precursor Cs(2)[Ru(VI)NCl(5)], at room temperature in water, produces K(2)(Me(2)NH(2))(2)H(2)[gamma-XW(10)O(38){RuN}(2)], X = Si (DMA-1 a) or Ge (DMA-1 b). The X-ray crystal structures of both complexes show monomeric complexes with highly unusual vicinal terminal metal-nitrido units. The Ru[triple bond]N bond lengths are 1.594(10) and 1.612(11) A in 1 a and 1 b, respectively. EXAFS studies confirmed the key structural assignments from X-ray crystallography. The XANES spectrum of DMA-1 a, diamagnetism, NMR ((29)Si and (183)W) chemical shifts, voltammetric behavior, reductive titrations with [PW(12)O(40)](4-), and computational data are all consistent with d(2) Ru(VI) centers in these complexes. The FT-IR and Raman spectra show the expected vibrational modes of the {gamma-XW(10)} unit and the Ru[triple bond]N stretch at 1080 cm(-1), respectively. Interestingly, reduction of DMA-1 a by 4 equivalents of [PW(12)O(40)](4-) produces NH(3) in nearly quantitative yield. Cyclic voltammetry versus pH and calculations provide the energetics for the possible two-electron reduction and two-proton addition processes in this reaction.

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Oxidation of pentaamminecarbonylosmium(2+) to .mu.-dinitrogen-bis(cis-tetraamminecarbonylosmium)(4+)

Cited by 64 publications

References 2 publications

Catalytic Ammonia Oxidation to Dinitrogen by Hydrogen Atom Abstraction

Catalytic Ammonia Oxidation to Dinitrogen by Hydrogen Atom Abstraction

Photolysis of Aqueous [(NH₃)₅Os(μ‐N₂)Os(NH₃)₅]⁵⁺: Cleavage of Dinitrogen by an Intramolecular Photoredox Reaction

Vicinal Dinitridoruthenium‐Substituted Polyoxometalates γ‐[XW₁₀O₃₈{RuN}₂]⁶⁻ (X=Si or Ge)

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Oxidation of pentaamminecarbonylosmium(2+) to .mu.-dinitrogen-bis(cis-tetraamminecarbonylosmium)(4+)

Cited by 64 publications

References 2 publications

Catalytic Ammonia Oxidation to Dinitrogen by Hydrogen Atom Abstraction

Catalytic Ammonia Oxidation to Dinitrogen by Hydrogen Atom Abstraction

Photolysis of Aqueous [(NH3)5Os(μ‐N2)Os(NH3)5]5+: Cleavage of Dinitrogen by an Intramolecular Photoredox Reaction

Vicinal Dinitridoruthenium‐Substituted Polyoxometalates γ‐[XW10O38{RuN}2]6− (X=Si or Ge)

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Photolysis of Aqueous [(NH₃)₅Os(μ‐N₂)Os(NH₃)₅]⁵⁺: Cleavage of Dinitrogen by an Intramolecular Photoredox Reaction

Vicinal Dinitridoruthenium‐Substituted Polyoxometalates γ‐[XW₁₀O₃₈{RuN}₂]⁶⁻ (X=Si or Ge)