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《Journal of organometallic chemistry》1986,306(1):89-98
The effect of substituents in the Cp ligands on the electronic structure has been studied for the 1,1′-disubstituted ferrocenes Fe(CpX)2, with X = C2H5, OCH3, CN, COCH3, COOCH3, OOCCH3, CH2C6H5, or C6H5, by UV photoelectron spectroscopy and by CNDO /2 calculations. The energy gap between the 2E2g and 2AT1g ion states, 0.36 eV in the parent ferrocene, is affected only by the COCH3 and COOCH3 substituents, which lower it to 0.22 and 0.28 eV, respectively. Splitting of e1u(π) level due to the lowering of the symmetry is the only effect observed in the photoelectron spectra. There is a strong conjugation between the phenyl and cyclopentadienyl β-orbitals in 1,1′-diphenylferrocene. The changes in the a1g(d) ionization energy calculated by the ΔSCF method using CNDO /2 total energies are in a good agreement with the experimental data. 相似文献
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The Pople-Santry-Segal CNDO/2 method and the modified CNDO/2 version worked out recently by Clack for transition-metal complexes have been extended to the full periodic table. 相似文献
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The empirical evaluation of the core matrix elements in the CNDO method is modified and the parameters are adjusted to give optimal values for heats of atomization, bond lengths, bond angles and force constants.
Zusammenfassung Die empirischen Ansätze der CNDO-Methode für die Core-Matrixelemente werden modifiziert und die Parameter abgeändert, um möglichst gute Werte für Bildungswärmen aus den Atomen, Bindungslängen, Valenzwinkel und Kraftkonstanten zu erhalten.
Resumé L'évaluation empirique des éléments de matrice de coeur dams la méthode CNDO et les paramèters sont modifiés en vue de dormer des valeurs optimaux pour les énergies d'atomisation, les distances interatomiques, les angles de valence et les constants de force.相似文献
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Lutskii A. E. Marchenko T. N. Poltoratskaya I. A. Gordienko V. G. 《Theoretical and Experimental Chemistry》1977,12(2):178-181
Theoretical and Experimental Chemistry - 相似文献
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Enthalpies of the decomposition reactions MX2L2(c)→MX2(c) + 2L (g), where M is Mn, Co, Ni, Cu, or Cd, X is Cl and/or Br, and L is benzothiazole or 2-methyl-benzothiazole have been measured by use of a differential scanning calorimeter. Specific heats and enthalpies of sublimation of some of the complexes have been obtained. 相似文献
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本文将Pople的闭壳层CNDO/2程序改编成将原子中s,p,d亚层分开处理,并扩展到可计算锆化合物的CNDO/2-TM程序;选取了锆的有关参数;计算了Cp_2ZrX_2(X=F,Cl)分子的电子结构.得到的氯化物分子轨道的能级次序和间隔与光电子能谱相符.计算的偶极矩为5.88D,与实验值相近.计算结果还说明Cp_2ZrX_2是有一定离子性的共价化合物.中心锆原子约呈 1价.金属锆的5s轨道参与茂环的σ键,5p轨道通过移入电子参与茂环σ键,而4d轨道则参与茂环的π键,但成键所占成分不大.Zr-F键的离子性占51%,Zr-Cl键的离子性占44%,Zr-Cp键的共价性在84~93%之间. 相似文献
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《Advances in Molecular Relaxation and Interaction Processes》1979,14(4):297-303
Using a recently modified INDO method the equilibrium intermolecular distance and heats of formation of various types of molecular complexes (CT, HB, CTTS, etc.) have been calculated. The results obtained are in reasonable agreement with available ab initio studies. 相似文献
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The electronic structure and the conformational analysis of some Ni(PX3)4 (X = F, OCH3, Cl, CH3, H) complexes are investigated within the framework of the previously described extended CNDO/2 method in order to interpret their magneto-optical behaviour and to propose a suitable scheme for the electronic content of a metal-ligand ( + ) dative bond. Chatt and Wilkinson's pattern, used up to now, is criticized and a new scheme is proposed which — taking accurately the role of electronegativity into account and abiding by Pauling's principle of electroneutrality — fits well the sets of available physico-chemical data and allows us to understand whyab initio bonds overlap populations as well as IR force constants are low for any metal-ligand ( + ) dative bond. 相似文献