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1.
过渡金属络合物荷移光谱的研究   总被引:1,自引:0,他引:1  
在配位场近似下,用不可约张量方法对具有O_4对称性的FeCl_6~(3-)及与其结构相似的过渡金属络合物的Hamilton矩阵进行了矩阵分割,得到了一种计算荷移光谱的简单方法.在计算中采用方案,考虑了纯组态内部的Coulomb作用和旋轨作用,忽略了不同组态间的Coulomb作用.并采取冻结轨道近似.计算结果与实验光谱数据符合较好.  相似文献   

2.
徐元耀 《有机化学》1985,5(1):44-59
过渡金属化学已发展成为有机合成的重要方法,本文综述了它在精细有机合成中应用的一些进展。叙述了金属有机化合物作为亲电体与亲核试剂反应,金属有机化合物作为亲核体与亲电试剂反应,以及偶合和环化反应。应用这些反应可以巧妙地合成若干天然产物。  相似文献   

3.
过渡金属络合物催化乙烯齐聚   总被引:2,自引:0,他引:2  
综述了乙烯齐聚的最新成果,重点阐述了用于乙烯齐聚的新型催化剂,讨论了烯烃高聚与齐聚催化剂的关系,烯烃高聚与齐聚的反应机理相同,。差别主要在于烯烃插入与β-H消除反应的速率,第IV副族金属络合物主要催化乙烯齐聚,第Ⅲ副族金属主要催化乙烯高聚,改变茂金属催化体系的助催化剂和反应条件可得到齐聚产物,选择体积较小配体的第Ⅷ族金属络合物,有利于β-H消除得到齐聚产物。  相似文献   

4.
武轶  张正之 《分析化学》1994,22(9):913-915
本文报道了采用场解吸电离质谱(FDMS)技术获得的膦桥过渡金属杂双核络合物系列化合物的质谱图,讨论了该系列络合物的裂解规律和离子源条件下的稳定性。结果表明,FDMS技术对研究膦桥过渡金属杂双核络合物是有效的方法。  相似文献   

5.
利用不可约张量方法讨论了过渡金属络合物自旋哈密顿。在考虑自旋轨作用、电子与其它电子旋轨作用、自旋-自旋偶极作用、Fermi作用和外磁场作用的近似下,得到了由分子参量表示的自旋哈密顿参量。在原子轨道近似下,近似地计算了红宝石的g因子,结果与实验符合得相当好,表明用本法解释过渡金属络合物的ESR谱是成功的。  相似文献   

6.
研究了多种不同过渡金属络合物对单重态氧的猝灭问题。结果表明过渡金属络合物猝灭单重态氧的能力主要和络合物分子的几何构型有关。能形成平面四方形结构的络合物由于中心金属原子易于和1O2分子相接近因而具有强的猝灭1O2的能力,反之形成四面体形结构的络合物则猝灭能力减弱。  相似文献   

7.
过渡金属配合物的相转移反应   总被引:7,自引:0,他引:7  
本文综述了相转移条件下过滤金属配合物催化有机合成的反应的进展。按羰基化反应、偶联反应、烃化反应、加成反应、还原反应及氧化反应等分别给予评述。  相似文献   

8.
9.
概述了过渡金属氢化物尤其是钌氢配合物的氧化加成、M-X还原、质子化、过渡金属氢化物转化和原子簇过渡金属配合物氢聚等合成方法的进展情况.  相似文献   

10.
过渡金属催化的碳-氢(C-H)键活化因其优异的原子经济性及步骤简便性在过去几十年间蓬勃发展,已成为当前构建复杂化合物最常用的策略之一.对该过程中活性中间体的热力学研究有助于加深人们对反应机理的理解,指导新催化剂、新反应的理性设计.然而,近年来该领域的发展颇为缓慢,相应的报道十分零散,缺少系统的归纳和总结.本综述简要梳理...  相似文献   

11.
Hydrothermal reactions of NaN3, 1, 10‐phenanthroline or 2, 2′‐bipyridine and transition metal cations including ZnII or CoII in basified aqueous solutions yielded the three complexes, [Zn2(bipy)2(N3)4]n ( 1 ), [Zn(phen)(N3)2]n ( 2 ), and [Co(phen)2(N3)2] ( 3 ), which were characterized by X‐ray crystallography. All three complexes crystallize in the triclinic system, space group P1¯, with a = 6.5506(2), b = 10.8441(6), c = 16.893(2)Å, α = 96.333(5), β = 95.361(7), γ = 90.548(6)° for 1 ; a = 7.0302(10), b = 10.0590(14), c = 10.4550(15)Å, α = 109.372(2), β = 103.980(2), γ = 106.137(2)° for 2 ; and a = 8.1722(2), b = 11.0332(3), c = 12.5066(2)Å, α = 82.681(8), β = 82.457(9), γ = 72.991(7)° for 3 , respectively. The photoluminescence spectra for compounds 1 and 2 have also been studied.  相似文献   

12.
This article analyzes the nature of the chemical bond in coinage metal halides using high-level ab initio Valence Bond (VB) theory. It is shown that these bonds display a large Charge-Shift Bonding character, which is traced back to the large Pauli pressure arising from the interaction between the bond pair with the filled semicore d shell of the metal. The gold-halide bonds turn out to be pure Charge-Shift Bonds (CSBs), while the copper halides are polar-covalent bonds and silver halides borderline cases. Among the different halogens, the largest CSB character is found for fluorine, which experiences the largest Pauli pressure from its σ lone pair. Additionally, all these bonds display a secondary but non-negligible π bonding character, which is also quantified in the VB calculations.  相似文献   

13.
马雪璐  李蒙  雷鸣 《化学学报》2023,81(1):84-99
多核过渡金属配合物作为一类广泛应用的均相催化剂,其设计灵感往往来自天然酶的多金属活性位点所发挥的重要作用.目前,三核金属配合物作为活化小分子的多金属催化剂受到了广泛的关注.为深入理解三核过渡金属配合物在催化反应中作用特点,对近年报道的代表性三核过渡金属配合物按金属中心进行分类,并对配体环境形成特点及催化应用进行综述.从金属中心出发,讨论了三核过渡金属配合物的几何结构和电子特征;从配体环境出发,总结了关联三个独立的金属位点的配位环境特征;在催化应用方面,重点综述了三核过渡金属配合物在涉及特定化学键活化反应的催化作用机制,最后对三核过渡金属配合物的催化应用前景进行展望.  相似文献   

14.
15.
Although silylene-carbonyl complexes are known for decades, only recently isolable examples have been accomplished. In this work, the bonding situation is re-evaluated to explain the origins of their remarkable stability within the Kohn-Sham molecular orbital theory framework. It is shown that the chemical bond can be understood as CO interaction with the silylene via a donor-acceptor interaction: a σ-donation from the σCO into the empty p-orbital of silicon, and a π-back donation from the sp2 lone pair of silicon into the π*CO antibonding orbitals. Notably, it was established that the driving force behind the surprisingly stable Si−CO compounds, however, is another π-back donation from a perpendicular bonding R−Si σ-orbital into the π*CO antibonding orbitals. Consequently, the pyramidalization of the central silicon atom cannot be associated with the strength of the π-back donation, in sharp contrast to the established chemical bonding model. Considering this additional bonding interaction not only shed light on the bonding situation, but is also an indispensable key for broadening the scope of silylene-carbonyl chemistry.  相似文献   

16.
By reaction of pentafluorophenylhydrazine with metal chlorides the complexes M(NH2NHC6F5)4Cl2 (M = Co, Ni), M(NH2NHC6F5)2Cl2 (M = Mn, Fe, Pd, Zn, Cd), Cu(NH2NHC6F5)Cl, and Hg(NH2NHC6F5)2Cl were obtained. From Cr(CO)6 and pentafluorophenylhydrazine the complex Cr(CO)5(NH2NHC6F5) was synthesized.  相似文献   

17.
The usage of calix[n]arenes as ancillary poly(phenolate) ligands is a rapidly developing area in coordination chemistry. This article focuses on the synthesis, structure and reactivity of calix[4]arene‐ and calix[4]arene ether‐stabilized imido complexes of group 4 — 6 transition metals as well as on the comparison of calix[4]arene dialkyl ethers in particular with other widely employed related ligand systems such as salenes, porphyrins and tetraazaannulenes. Contrary to these nitrogen containing systems, it is much easier to control the charge of the ligand system through the degree of alkylation of the calixarene's lower rim without a major change in the geometry of the resulting metal complex. This could lead to isoelectronic and structurally closely related transition metal complex fragments for metals in neighboring groups of the periodic table or for metals in different oxidation states. The “intrinsic” reactivity of metal imido linkages might therefore be explored using calix[4]arenes and calix[4]arene ethers and first results are summarized in this research report.  相似文献   

18.
A study on the reactivity of the N-heterocyclic silylene Dipp2NHSi (1,3-bis(diisopropylphenyl)-1,3-diaza-2-silacyclopent-4-en-2-yliden) with the transition metal complexes [Ni(CO)4], [M(CO)6] (M=Cr, Mo, W), [Mn(CO)5(Br)] and [(η5-C5H5)Fe(CO)2(I)] is reported. We demonstrate that N-heterocyclic silylenes, the higher homologues of the now ubiquitous NHC ligands, show a remarkably different behavior in coordination chemistry compared to NHC ligands. Calculations on the electronic features of these ligands revealed significant differences in the frontier orbital region which lead to some peculiarities of the coordination chemistry of silylenes, as demonstrated by the synthesis of the dinuclear, NHSi-bridged complex [{Ni(CO)2(μ-Dipp2NHSi)}2] ( 2 ), complexes [M(CO)5(Dipp2NHSi)] (M=Cr 3 , Mo 4 , W 5 ), [Mn(CO)3(Dipp2NHSi)2(Br)] ( 9 ) and [(η5-C5H5)Fe(CO)2(Dipp2NHSi-I)] ( 10 ). DFT calculations on several model systems [Ni(L)], [Ni(CO)3(L)], and [W(CO)5(L)] (L=NHC, NHSi) reveal that carbenes are typically the much better donor ligands with a larger intrinsic strength of the metal–ligand bond. The decrease going from the carbene to the silylene ligand is mainly caused by favorable electrostatic contributions for the NHC ligand to the total bond strength, whereas the orbital interactions were often found to be higher for the silylene complexes. Furthermore, we have demonstrated that the contribution of σ- and π-interaction depends significantly on the system under investigation. The σ-interaction is often much weaker for the NHSi ligand compared to NHC but, interestingly, the π-interaction prevails for many NHSi complexes. For the carbonyl complexes, the NHSi ligand is the better σ-donor ligand, and contributions of π-symmetry play only a minor role for the NHC and NHSi co-ligands.  相似文献   

19.
The reaction of molybdenum, tungsten and manganese carbonyls with several thiazole heterocycle ligands yielded a number of coordinated transition metal complexes 1 – 10 . Of these complexes 1 – 6 are new compounds which have not been reported to date. The structures of new compounds were characterized by FT‐IR and 1H‐NMR spectroscopy as well as single‐crystal X‐ray diffraction analysis. Complexes 1 – 10 are carbon monoxide releasing molecules that show structure‐related anti‐cancer activity. The cytotoxicity of all compounds on Hela cells was evaluated by MTT assay, and the results show that carbon monoxide releasing molecules containing such Schiff base ligands may have biomedical applications for their anti‐tumor effect.  相似文献   

20.
Thetheoreticalstudyofsmallmoleculescontainingtransitionmetalatomsisoneofthemostactiveareasinquantumchemistry'becauseofthemanyimportantmaterialsandcatalyticapplicationsofthetransitionmetalsandalsotheirimpoytanceinbiology.Therehavebeenveryextensivestudiesonfirstandsecondrowtransitionmetalhydrides"',oxides4-6andthetransitionmetaldimers7-9.Buttheoreticalstudiesonthethirdrowtransitionmetalcompoundsareratherscarceg-11.Iridiumisanimportantelementforcatalyticreactions,andtheknowledgeoftheinteractionbe…  相似文献   

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