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191.
1H and 13C NMR chemical shifts of iron porphyrin complexes are determined mainly by the spin densities at the peripheral carbon and nitrogen atoms caused by the interaction between paramagnetic iron 3d and porphyrin molecular orbitals. This review describes how the half‐occupied iron 3d orbitals such as dπ(dxz, dyz), dxy, d, and d‐ interact with a specific porphyrin molecular orbital and affect the 1H and 13C NMR chemical shifts in planar, ruffled, saddled, and domed complexes. Revealing the relationship between the orbital interactions and NMR chemical shifts is quite important to determine the fine electronic structures of synthetic iron porphyrin complexes as well as naturally occurring heme proteins. 相似文献
192.
193.
Kiyoshi Kobayashi Masateru Nishioka Koichi Sato Tomoya Inoue Satoshi Hamakawa Tatsuo Tsunoda 《Journal of Solid State Electrochemistry》2006,10(8):629-634
An oxygen-permeable composite constituted to oxide ionic conductor phase (Ce0.75Nd0.25O1.875) and oxide electronic conductor phase (Nd1.8Ce0.2CuO4) was prepared using the acetate pyrolysis method. Based on electrical conductivity measurements, total electrical conductivity
of 75 mol% Ce0.75Nd0.25O1.875–25 mol% Nd1.8Ce0.2CuO4 composite material was governed by the electronic conduction paths. With respect to the oxygen permeation properties, the
results showed that oxygen permeation properties were unexplainable by a simple composite rule using the electrical transport
properties of the bulk Ce0.75Nd0.25O1.875 and the bulk Nd1.8Ce0.2CuO4. 相似文献
194.
Addition of tert-butylisocyanide (tBuNC) to a CD2Cl2 solution of the bis(perchlorato)(meso-tetramesitylporphyrinato) iron(III) cation radical leads to the formation of the corresponding bis(adduct), [Fe(TMP)(tBuNC)2]2+, whose electronic structure is in sharp contrast to that of the corresponding imidazole(HIm) complex, [Fe(TMP)(HIm)2]2+; the former adopts the S = 0 while the latter exhibits the S = 1 electronic ground state. 相似文献
195.
1,2,3-Benzotriazin-4(3H)-ones reacted with internal and terminal alkynes in the presence of a nickel(0)/phosphine catalyst to give a wide range of substituted 1(2H)-isoquinolones in high yield. The reaction proceeded through denitrogenative activation of the triazinone moiety and the following insertion of alkynes. 相似文献
196.
The electronic structures of six-coordinate iron(III) octaethylmonoazaporphyrins, [Fe(MAzP)L 2] (+/-) ( 1), have been examined by means of (1)H NMR and EPR spectroscopy to reveal the effect of meso-nitrogen in the porphyrin ring. The complexes carrying axial ligands with strong field strengths such as 1-MeIm, DMAP, CN (-), and (t)BuNC adopt the low-spin state with the (d xy ) (2)(d xz , d yz ) (3) ground state in a wide temperature range where the (1)H NMR and EPR spectra are taken. In contrast, the complexes with much weaker axial ligands, such as 4-CNPy and 3,5-Cl 2Py, exhibit the spin transition from the mainly S = 3/2 at 298 K to the S = 1/2 with the (d xy ) (2)(d xz , d yz ) (3) ground state at 4 K. Only the THF complex has maintained the S = 3/2 throughout the temperature range examined. Thus, the electronic structures of 1 resemble those of the corresponding iron(III) octaethylporphyrins, [Fe(OEP)L 2] (+/-) ( 2). A couple of differences have been observed, however, in the electronic structures of 1 and 2. One of the differences is the electronic ground state in low-spin bis( (t)BuNC) complexes. While [Fe(OEP)( (t)BuNC) 2] (+) adopts the (d xz , d yz ) (4)(d xy ) (1) ground state, like most of the bis( (t)BuNC) complexes reported previously, [Fe(MAzP)( (t)BuNC) 2] (+) has shown the (d xy ) (2)(d xz , d yz ) (3) ground state. Another difference is the spin state of the bis(3,5-Cl 2Py) complexes. While [Fe(OEP)(3,5-Cl 2Py) 2] (+) has maintained the mixed S = 3/2 and 5/2 spin state from 298 to 4 K, [Fe(MAzP)(3,5-Cl 2Py) 2] (+) has shown the spin transition mentioned above. These differences have been ascribed to the narrower N4 cavity and the presence of lower-lying pi* orbital in MAzP as compared with OEP. 相似文献
197.
Nishimura D Oshikiri T Takashima Y Hashidzume A Yamaguchi H Harada A 《The Journal of organic chemistry》2008,73(7):2496-2502
Novel [2]rotaxanes bearing alpha-cyclodextrin (alpha-CD) derivatives and a diphenylacetylene axis molecule with trinitrobenzene as a bulky stopper have been prepared to investigate the relative rotary movement of a ring relative to an axis molecule and that of an axis molecule in a ring by NMR techniques. [2]Rotaxanes 2 and 3 were composed of alpha-CD derivatives (2: 6-phenyl-amide-alpha-CD; 3: 6-stilbene-amide-alpha-CD). The protons of alpha-CDs in rotaxanes were thoroughly assigned by the two-dimensional NMR techniques (TOCSY, COSY, ROESY, HMQC, and HMBC). The protons of alpha-CD in rotaxane 1 did not show splitting, whereas the resonance peak shifts and splitting for the corresponding protons of alpha-CD derivatives in rotaxanes 2 and 3 were observed by the shielding and deshielding effects from a diphenylacetylene axis molecule. The splitting of resonance peaks was closely related to the rotary movements of alpha-CDs and an axis molecule. We supposed that alpha-CD in rotaxane 1 rotates freely around a diphenylacetylene axis molecule, and vice versa, whereas the rotary movement of alpha-CD derivatives and the axis molecules of rotaxanes 2 and 3 were restricted by the steric repulsion between the substituent group of alpha-CD and the stopper group of an axis molecule. To estimate the relative rotary movement of CDs and an axis molecule in rotaxanes, the rotational correlation time (tauc) of rotaxanes was measured by 13C NMR. The results indicate that the corresponding rotary movement of the modified alpha-CD and the axis molecules in rotaxanes 2 and 3 depends on the size of the substituent group. 相似文献
198.
Benzodipyrrole‐based Donor–Acceptor‐type Boron Complexes as Tunable Near‐infrared‐Absorbing Materials
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Benzodipyrrole‐based donor–acceptor boron complexes were designed and synthesized as near‐infrared‐absorbing materials. The electron‐rich organic framework combined with the Lewis acidic boron co‐ordination enabled us to tune the LUMO energy level and the HOMO–LUMO gap (i.e.,the absorption wavelength) by changing the organic acceptor units, the number of boron atoms, and the substituents on the boron atoms. 相似文献
199.
Palladium-catalyzed cross-coupling reactions under Suzuki, Sonogashira, and Stille conditions afford 3-aryl (9-12) and 3-arylethynyl N-confused porphyrin (NCP) silver(III) complexes (13-15) from the 3-bromo NCP complex (4) in ca. 70% yields along with the transmetalated products, 3-substituted NCP palladium(II) complexes (11-Pd to 15-Pd), in 10-30% yields. Substitution at 3-position was confirmed by the single crystal X-ray structures of 9, 13-Ag, and 13-Pd. The arylethynyl groups or five-membered heterocyclic aromatic rings at 3-position largely affected the optical properties of N-confused porphyrin, in which the longest absorption maxima of the Q-bands are shifted bathochromically by 30-120 nm. The electronic effect of substituent differs largely between palladium and silver complexes reflecting the different π-electron delocalization pathway of NCP cores. 3-Aryl- and 3-arylethynyl NCP silver(III) complexes were easily demetalated to afford the corresponding free base porphyrins by the treatment of sodium borohydride. 相似文献
200.
We consider the Cauchy problem for the generalized Zakharov–Kuznetzov equation \(\partial _t u + \partial _x \Delta u = \partial _x ( u^{m+1} )\) on two or three space dimensions. We mainly study the two dimensional case and give the local well-posedness and the small data global well-posedness in the modulation space \(M_{2,1}(\mathbb {R}^2)\) for \(m \ge 4\). Moreover, for the quartic case (namely, \(m = 3\)), the local well-posedness in \( M_{2,1}^{1/4}(\mathbb {R}^2)\) is given. The well-posedness on three dimensions is also considered. 相似文献