Isolation and Identification of Flavone Type of Two Compounds from Salix matsudana

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Isolation and the Jump Operator

We show the existence of a high d. c. e. degree d and a low₂ c.e. degree a such that d is isolated by a .     

Selective Preparation of Phosphorus Mononitride (P≡N) from Phosphinoazide and Reversible Oxidation to Phosphinonitrene

The interstellar candidate phosphorus mononitride PN, a metastable species, was generated through high-vacuum flash pyrolysis of (o-phenyldioxyl)phosphinoazide in cryogenic matrices. Although the PN stretching band was not directly detected because of its low infrared intensity and possible overlaps with other strong bands, o-benzoquinone, carbon monoxide, and cyclopentadienone as additional fragmentation products were clearly identified. Moreover, an elusive o-benzoquinone-PN complex formed when (o-phenyldioxyl)phosphinoazide was exposed to UV irradiation at λ=254 nm. Its recombination to (o-phenyldioxyl)-λ⁵-phosphinonitrile was observed upon irradiation with the light at λ=523 nm, which demonstrates for the first time the reactivity of PN towards an organic molecule. Energy profile computations at the B3LYP/def2-TZVP density functional theory level reveal a concerted mechanism. To provide further evidence, UV/Vis spectra of the precursor and the irradiation products were recorded and agree well with time-dependent DFT computations.     

Lewis Acid Supported Nickel Nitrenoids

Metalation of the polynucleating ligand ^F,tbsLH₆ (1,3,5-C₆H₉(NC₆H₃−4-F−2-NSiMe₂^tBu)₃) with two equivalents of Zn(N(SiMe₃)₂)₂ affords the dinuclear product (^F,tbsLH₂)Zn₂ ( 1 ), which can be further deprotonated to yield (^F,tbsL)Zn₂Li₂(OEt₂)₄ ( 2 ). Transmetalation of 2 with NiCl₂(py)₂ yields the heterometallic, trinuclear cluster (^F,tbsL)Zn₂Ni(py) ( 3 ). Reduction of 3 with KC₈ affords [KC₂₂₂][(^F,tbsL)Zn₂Ni] ( 4 ) which features a monovalent Ni centre. Addition of 1-adamantyl azide to 4 generates the bridging μ³-nitrenoid adduct [K(THF)₃][(^F,tbsL)Zn₂Ni(μ³-NAd)] ( 5 ). EPR spectroscopy reveals that the anionic cluster possesses a doublet ground state (S = ). Cyclic voltammetry of 5 reveals two fully reversible redox events. The dianionic nitrenoid [K₂(THF)₉][(^F,tbsL)Zn₂Ni(μ³-NAd)] ( 6 ) was isolated and characterized while the neutral redox isomer was observed to undergo both intra- and intermolecular H-atom abstraction processes. Ni K-edge XAS studies suggest a divalent oxidation state for the Ni centres in both the monoanionic and dianionic [Zn₂Ni] nitrenoid complexes. However, DFT analysis suggests Ni-borne oxidation for 5 .