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91.
R. B. King T. E. Bitterwolf W. B. Scallorn C. A. Weiss 《Phosphorus, sulfur, and silicon and the related elements》2013,188(6-7):1567-1570
A reactive ( i -Pr 2 NP) 2 Fe 2 (CO) 6 intermediate, which is generated by heating ( i -Pr 2 NP) 2 COFe 2 (CO) 6 in boiling toluene, adds to a variety of multiple bonds including the C=O bonds of aldehydes, ketones, maleic anhydride, and phthalic anhydride; the C L N bonds of saturated nitriles; and the C=C bond of acrylonitrile. Photolysis at <380 nm of ( i -Pr 2 NP) 2 COFe 2 (CO) 6 in a Nujol matrix at 90 K also results in extrusion of the phosphorus-bridging CO group to give a pattern of infrared metal x (CO) frequencies suggestive of an intermediate of D 2 h symmetry. 相似文献
92.
93.
The mechanism of photolysis for a cyanometalate coordination polymer composed of [(NC)5FeII---CN---PtIV(NH3)4]n repeat units, is deduced based on the results of several photogalvanic techniques. These techniques are validated through characterization of the previously established photochemistry of [(NC)5FeII---CN---PtIV(NH3)4---NC---FeII(CN)5]4−. Analysis of the polymer photoproducts indicates the presence of iron centers with a redox potential higher than that of the expected photoproduct, ferricyanide. Additionally, the charge collected at the electrode surface is greater than the number of iron centers freed from the polymer network by photolysis. A mechanism based on the creation of oxidized ferricyanide centers with multiple bridging cyanides is proposed. Each bridging cyanide to a Pt center increases the redox potential of the associated ferricyanide center. Ferricyanide centers with a sufficient number of bridging cyanides have redox potentials high enough to oxidize various halides to the corresponding halogen. The ability to convert chloride to chlorine suggests potential applications in the area of solar energy conversion. 相似文献
94.
Photochemistry based on acenes and their derivatives is one of the emerging research areas in the field of polycyclic aromatic hydrocarbons (PAHs). However, due to the increased reactivity of larger acenes towards light and singlet oxygen, it is difficult to precisely control their photochemical reactions. Therefore, the unexpected reactivity of acene-based molecules brings about two challenging topics: how to design stable acenes and how to utilize the photochemistry to design new acene-based functional materials. In this review, we first focus on the mechanism of photochemistry of acenes to theoretically understand how these reactions could have happened. Next, we will give a summary on both acene-based photocyclization and photooxidation reactions. 相似文献
95.
This article reviewed recent progresses in the design of a new class of chemical oscillators and developed a generic model that could qualitatively reproduce those photochemical oscillations seen in experiments. The two oscillators discussed in this report are based on the photolysis of 1,4-benzoquinone and its derivatives, in which external illumination is vital in initiating and sustaining the reaction processes. Nonlinear behavior in these two photo-controlled chemical oscillators are analyzed as a function of light intensity and the initial concentration of reagents including 1,4-benzoquinone, 1,4-hydroquinone, 2-methyl-1,4-benzoquinone, bromate, and sulfuric acid. A generic model proposed initially for the uncatalyzed bromate-aromatic compound reactions was modified here to account for the photolysis of 1,4-benzoquinone or 2-methyl-1,4-benzoquinone. The modified model qualitatively reproduced chemical oscillations and their dependence on light intensity. 相似文献
96.
《Journal of Coordination Chemistry》2012,65(18):1933-1940
The complexes (NH4)2[MoO2(C2H2O3)2]·H2O, (NH4)2[MoO2(C8H6O3)2] and (NH4)2[MoO3(C4H4O6)]·H2O were prepared by reaction of MoO3 with glycolic, mandelic and tartaric acids, respectively. The complexes were characterized by elemental and thermal analysis, IR spectroscopy and X-ray diffraction. Crystals of the glycolate and tartarate complexes are orthorhombic and the mandelate complex is monoclinic. Elemental and thermal analysis data showed that the glycolate and tartarate complexes are monohydrated. Hydration water is not present in the structure of the mandelate complex. IR spectra showed COO? is involved in coordination as well as the oxygen atom of the deprotonated hydroxyl group of the α-carbon. The glycolate molybdenum complexes with general formula M2[MoO2(C2H2O3)2]·nH2O, where M is an alkali metal and n?=?1 or ½, were also prepared and characterized. Aqueous solutions of the glycolate complex become blue and mandelate and tartarate complexes change to yellow or brown when exposed to UV-radiation. 相似文献
97.
《Journal of Coordination Chemistry》2012,65(12):1039-1046
Photoredox reactions in irradiated methanolic solutions of trans-[Fe(R′-sal-R2-en) (CH3OH)(NCS)] complexes, where R′-sal-R2-en2? are tetradentate open-chain N,N′-1,1-R2-ethylenebis(R′-salicylideneiminato) ligands (R?=?H or CH3; R′?=?H, 5-Cl, 5-Br, 3,5-Br2, 3-OCH3, 4-OCH3), have been explored and a mechanism suggested. The complexes are redox-stable in the dark in methanol. Continuous irradiation of solutions in the region of intraligand (IL) or ligand-to-metal charge transfer (LMCT) transitions leads to photoreduction of Fe(III) to Fe(II) and formation of formaldehyde (CH2O). Formation of polystyrene-containing bonded NCS, when irradiating the complexes in the presence of styrene used as a radical scavenger, indicates that the primary photoreduction of Fe(III) to Fe(II) is accompanied by oxidation of NCS? to the ?NCS radical. R′-sal-R2-en ligands have little effect on the photoinduced redox processes. The quantum yield of Fe(II) formation, ΦFe(II), as a quantitative parameter of photoredox efficiency, decreases significantly with increasing wavelength of incident radiation, and is slightly influenced by the peripheral groups, R, of R′-sal-R2-en. 相似文献
98.
Sergio Abbate Tullio Caronna Francesca Fontana Fabrizio Gangemi Andrea Mele Walter Panzeri 《Tetrahedron》2006,62(1):139-148
The synthesis of four different monoaza[5]helicenes is reported, to complete the whole series of these compounds, so that systematic studies on their properties can be carried out. They were fully characterised via NMR. A theoretical approach to explain why ring closure occurs to give the most crowded compound is reported, in comparison with earlier calculation methods. 相似文献
99.
Systematic studies on the photo‐Fries rearrangement of different 9H‐carbazol‐2‐yl sulfonates 2 have shown that this type of conversion can be readily used for the preparative‐scale introduction of alkyl‐ or arylsulfonyl groups into polycyclic aromatic compounds under very mild conditions. A series of new 1‐sulfonyl‐ ( 3 ) or 3‐sulfonyl‐9H‐carbazoles ( 4 ) were prepared in medium‐to‐good yields, and characterized by UV/VIS, 1H‐NMR, and 13C‐NMR spectroscopy, as well as by elemental analysis. Effects of irradiation wavelength, solvent polarity, presence or absence of O2, and photosensitizers were studied in detail. 相似文献
100.
The quantum yield for arene displacement from (η6-C6H5Y)Cr(CO)3 was measured in 1,1,2-trifluorotrichloroethane (Y = NH2, OCH3, H, CHO, or CO2CH3). Values of 0.24, 0.27, 0.15, 0.17, and 0.32 were obtained respectively (λexc. = 355 nm). These values are significantly higher than those measured for photoinduced arene loss in hydrocarbon solvents using the same excitation wavelength. Laser flash photolysis of (η6-C6H5Y)Cr(CO)3 in 1,1,2-trifluorotrichloroethane (λexc. = 355 nm) resulted in the rapid formation (<10 ns) of Cr(CO)6. Matrix isolation experiments on (η6-C6H5Y)Cr(CO)3 (Y = H or CHO) at 12 K in CH4 or CO-doped CH4 matrixes using monochromatic irradiation confirmed the presence of two discrete excited states, one leading to CO-loss and the other to arene-loss. The results correlate with the calculated electron drift in the excited state derived from density functional theory and time dependent density functional theory calculations. 相似文献