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121.
Electronic transitions between Kramers doublets are often allowed for σ (x,y) and π(z) electric or magnetic dipole radiation and transverse MCD measures the interference between σ and π transition dipoles. For mixed-valence compounds, transverse MCD measures the interference between electron transfer (z) and single-ion (x,y) transition dipoles. 相似文献
122.
The hydrogen bond N·HO between the water and ammonia molecules has been investigated ab initio using the SCF LCAO MO method. The minimal and extended basis sets of Slater type orbitals were used. It was found that the energy of the hydrogen bond is equal to 6.44 kcal/mole and the equilibrium separation of the oxygen and nitrogen atoms in the dimer is 5.72 au. At this intermolecular distance there is only one minimum in the potential energy curve for the motion of proton. 相似文献
123.
Stanisaw Pasynkiewicz Antoni Pietrzykowski Lidia Trojanowska Piotr Sobota Lucjan Jerzykiewicz 《Journal of organometallic chemistry》1998,550(1-2)
The reaction of nickelocene with BrMgR, where R=CH2CH(CH3)C6H5, C2H5, (CH2)7CH3 and CH2CH2CH3, have been studied. It was found that the presence of β-hydrogen in R did not cause the total splitting of the carbon–nickel bond but alkylidynetrinickel clusters were formed. It is the first example of the synthesis of alkylidynetrinickel clusters (NiCp)3CR′ from the organonickel species possessing β-hydrogen. Besides trinickel clusters, the following compounds were always formed in all the studied reactions: (NiCp)4H2, (NiCp)6, CpNi(η3-C5H7) and (NiCp)2(μ-C5H6). The structure of (NiCp)3CCH(CH3)Ph has been determined by a single-crystal X-ray diffraction study. 相似文献
124.
Rachlewicz K Latos-Grazyński L Vogel E Ciunik Z Jerzykiewicz LB 《Inorganic chemistry》2002,41(7):1979-1988
Five-coordinate iron(III) 2,7,12,17-tetrapropylporphycene (TPrPc)Fe(III)X (X = C(6)H(5)O(-), Cl(-), Br(-), I(-), ClO(4)(-)) complexes have been investigated. The (1)H NMR spectra demonstrate downfield shifts for pyrrole resonances [(TPrPc)Fe(III)(C(6)H(5)O), 65.3 ppm; (TPrPc)Fe(III)Cl, 28.5 ppm] but large upfield ones for (TPrPc)Fe(III)Br (-7.8 ppm), (TPrPc)Fe(III)I (-49.4 ppm), and (TPrPc)Fe(III)ClO(4) (-77.1 ppm) (294 K, CD(2)Cl(2)). The pyrrole chemical shifts span the remarkable +70 to -80 ppm range. The variable-temperature (1)H NMR spectra of (TPrPc)Fe(III)X demonstrate anti-Curie behavior with a sign reversal for (TPrPc)Fe(III)Cl. These behaviors are consistent with the admixed S = 3/2, 5/2 ground electronic state with a dominating contribution of the S = 3/2 one. In terms of the chemical shift, (TPrPc)Fe(III)(ClO(4)) can be considered as an example of the purest S = 3/2 state in the investigated series. The extent of the S = 5/2 contribution in the admixed S = 3/2, 5/2 ground electronic state, as gradated solely the basis of the pyrrole proton paramagnetic shifts, is controlled by the strength of the axial ligand, following the magnetochemical series (Evans, D. R.; Reed, C. A. J. Am. Chem. Soc. 2000, 122, 4660). Significantly iron(III) 2,7,12,17-tetrapropylporphycene, soluble in typical organic solvents, can be considered as a universal framework to classify the ligand strength in a magnetochemical series, consistently using the beta-H pyrrole paramagnetic shifts as a fundamental criterion. The structure of (TPrPc)Fe(III)Cl has been determined by X-ray crystallography. The iron is five-coordinate with bonds of nearly equal length to the four pyrrole nitrogen atoms (Fe-N in the range 1.983(5)-2.006(6) A). The iron lies 0.583(1) A out of the mean plane of the macrocycle and 0.502(5) A out of the mean N(4) plane. In the solid, pairs of molecules are positioned about the center of symmetry so there is face-to-face pi-pi contact. The mean plane separation is 3.38 A, and the lateral shift of the porphycene center along the Fe-N bond is 4.490 A. The distance from one porphycene center to the other is 5.62 A, and the iron-iron separation is 6.304(2) A. 相似文献
125.
Aleksandra Jankowska Andrzej Kowalczyk Magorzata Rutkowska Marek Michalik Lucjan Chmielarz 《Molecules (Basel, Switzerland)》2021,26(6)
Aluminum containing silica spherical MCM-41 was synthesized and modified with copper by the template ion-exchange method (TIE) and its modified version, including treatment of the samples with ammonia solution directly after template ion-exchange (TIE-NH3). The obtained samples were characterized with respect to their chemical composition (ICP-OES), structure (XRD), texture (low temperature N2 sorption), morphology (SEM-EDS), form and aggregation of deposited copper species (UV-vis DRS), reducibility of copper species (H2-TPR), and surface acidity (NH3-TPD). The deposition of copper by the TIE-NH3 method resulted in much better dispersion of this metal on the MCM-41 surface comparing to copper introduced by TIE method. It was shown that such highly dispersed copper species, mainly monomeric Cu2+ cations, deposited on aluminum containing silica spheres of MCM-41, are significantly more catalytically effective in the NH3-SCR process than analogous catalysts containing aggregated copper oxide species. The catalysts obtained by the TIE-NH3 method effectively operated in much broader temperature and were less active in the side process of direct ammonia oxidation by oxygen. 相似文献
126.
Piotr Chmielewski Valery A. Ozeryanskii Lucjan Sobczyk Alexander F. Pozharskii 《Journal of Physical Organic Chemistry》2007,20(9):643-648
The primary 1H/2H isotope effect for a number of protonated naphthalene proton sponges (DMAN‐s) was measured and correlated with the δ(1H) value and IR spectroscopic characteristics of the [NHN]+ hydrogen bonds. A particular role of the unusual anharmonicity expressed in the isotopic ratio ISR ? is discussed when the fundamental vibrational levels are close to the barrier top for proton/deuteron motion. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
127.
128.
Janas Z Wiśniewska D Jerzykiewicz LB Sobota P Drabent K Szczegot K 《Dalton transactions (Cambridge, England : 2003)》2007,(20):2065-2069
The direct reaction between [VCl(3)(thf)3] or [VO(OEt)3] and 2,2'-thiobis{4-(1,1,3,3-tetramethyl-butyl)phenol (tbopH(2)) leads to the formation of [V(2)(micro-tbop-kappa(3)O,S,O)2Cl(2)(CH(3)CN)(2)] (1).4CH(3)CN or [V(2)(micro-OEt)2(O)2(tbop-kappa(3)O,S,O)2] (2), respectively, in high yield. Compounds 1 and 2 were characterized by chemical and physical techniques including X-ray crystallography and variable temperature magnetic susceptibility studies (J = -29.1 cm(-1)) for 1. Complexes 1 and 2 were supported on MgCl2 and when activated with aluminium alkyls, were found to effectively polymerize ethene to produce polyethylene with a narrow molecular weight distribution M(w)/M(n) approximately 3. 相似文献
129.
130.