Dataset Information

Molybdenum-Mediated N₂ -Splitting and Functionalization in the Presence of a Coordinated Alkyne.

ABSTRACT: A new [PCCP]-coordinated molybdenum platform comprising a coordinated alkyne was employed for the cleavage of molecular dinitrogen. The coordinated η² -alkyne was left unaffected during this reduction. DFT calculations suggest that the reaction proceeds via an initially generated terminal N₂ -complex, which is converted to a dinuclear μ-(η¹ :η¹ )-N₂ -bridged intermediate prior to N-N bond cleavage. Protonation, alkylation and acylation of the resulting molybdenum nitrido complex led to the corresponding N-functionalized imido complexes. Upon oxidation of the N-acylated imido derivative in MeCN, a fumaronitrile fragment was built up via C-C coupling of MeCN to afford a dinuclear molybdenum complex. The key finding that the strong N≡N bond may be cleaved in the presence of a weaker, but spatially constrained C≡C bond contradicts the widespread paradigm that coordinated alkynes are in general more reactive than gaseous N₂ .

SUBMITTER: Wagner HK

PROVIDER: S-EPMC9297880 | biostudies-literature | 2021 Dec

REPOSITORIES: biostudies-literature

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Molybdenum-Mediated N2 -Splitting and Functionalization in the Presence of a Coordinated Alkyne.

Wagner Hannah K HK Wadepohl Hubert H Ballmann Joachim J

Angewandte Chemie (International ed. in English) 20211103 49

A new [PCCP]-coordinated molybdenum platform comprising a coordinated alkyne was employed for the cleavage of molecular dinitrogen. The coordinated η2 -alkyne was left unaffected during this reduction. DFT calculations suggest that the reaction proceeds via an initially generated terminal N2 -complex, which is converted to a dinuclear μ-(η1 :η1 )-N2 -bridged intermediate prior to N-N bond cleavage. Protonation, alkylation and acylation of th ...[more]

PMID: 34618390

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Project description:By photodeposition of CrOx on SrTiO3-based semiconductors doped with aliovalent Mg(II) and functionalized with Ni/NiOx catalytic nanoparticles (economically significantly more viable than commonly used Rh catalysts), an increase in apparent quantum yield (AQYs) from ∼10 to 26% in overall water splitting was obtained. More importantly, deposition of CrOx also significantly enhances the stability of Ni/NiO nanoparticles in the production of hydrogen, allowing sustained operation, even in intermittent cycles of illumination. In situ elemental analysis of the water constituents during or after photocatalysis by inductively coupled plasma mass spectrometry/optical emission spectrometry shows that after CrOx deposition, dissolution of Ni ions from Ni/NiOx-Mg:SrTiO3 is significantly suppressed, in agreement with the stabilizing effect observed, when both Mg dopant and CrOx are present. State-of-the-art electron microscopy and energy-dispersive X-ray spectroscopy (EDX) and electron energy-loss spectroscopy (EELS) analyses demonstrate that upon preparation, CrOx is photodeposited in the vicinity of several, but not all, Ni/NiOx particles. This implies the formation of a Ni-Cr mixed metal oxide, which is highly effective in water reduction. Inhomogeneities in the interfacial contact, evident from differences in contact angles between Ni/NiOx particles and the Mg:SrTiO3 semiconductor, likely affect the probability of reduction of Cr(VI) species during synthesis by photodeposition, explaining the observed inhomogeneity in the spatial CrOx distribution. Furthermore, by comparison with undoped SrTiO3, Mg-doping appears essential to provide such favorable interfacial contact and to establish the beneficial effect of CrOx. This study suggests that the performance of semiconductors can be significantly improved if inhomogeneities in interfacial contact between semiconductors and highly effective catalytic nanoparticles can be resolved by (surface) doping and improved synthesis protocols.

Dataset Information

Molybdenum-Mediated N₂ -Splitting and Functionalization in the Presence of a Coordinated Alkyne.

Publications

Molybdenum-Mediated N<sub>2</sub> -Splitting and Functionalization in the Presence of a Coordinated Alkyne.

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