共查询到20条相似文献,搜索用时 31 毫秒
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Yves Jeannin 《Transition Metal Chemistry》1993,18(1):122-128
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Villanneau R Delmont R Proust A Gouzerh P 《Chemistry (Weinheim an der Bergstrasse, Germany)》2000,6(7):1184-1192
A series of polyoxomolybdate-incorporated organometallic complexes has been obtained by reaction of [MBr(CO)5] or solvated M(CO)3+ ions (M = Mn or Br) with (nBu4N)2[Mo2O7] in methanol, sometimes in the presence of triols of the type RC(CH2OH)3 (R = Me or CH2OH). Their molecular structures are related to those of previously described polyoxoalkoxomolybdates through the formal replacement of fac-MoO2(OR)+ units by topologically equivalent fac-M(CO)3+ units. Representative pairs of structurally related clusters include [Mo2O6(OMe)4-Re(CO)32]2- and [Mo4O10(OMe)6]2-, [Mo2O4MeC(CH2O)32Mn(CO)3]- and [Mo3O6(OMe)MeC(CH2O)32]-, [Mo2O4HOCH2C(CH2O)32Mn(CO)32] and [Mo4O8(OEt)2MeC(CH2O)32], [Mo6O16(OMe)2MeC(CH2O)32-Mn(CO)32]2- and [Mo8O20(OMe)4-MeC(CH2O)32]2-. Although the frameworks of the majority of derivatives are based on tetranuclear units which display the common rhomb-like structure, the alternative cubane-type arrangement is observed in [Mo2O5(OMe)5M(CO)32]-. 相似文献
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Nitrogenases mediate the reduction of many substrates other than dinitrogen and a summary is given. Several chemical systems that mimic aspects of nitrogenase reactivity, including transition metal complexes of alkynes and olefins, are outlined. Their protonation has been studied and their relevance to reduction of alkynes and olefins by nitrogenase is assessed. Cyclopropene is reduced by molybdenum nitrogenase to propene and cyclopropane. The reactions of cyclopropene with different transition metal complexes are discussed and a study of interactions of cyclopropenes with models for the active site of the nitrogenase enzyme are described. These models include transition metal hydrides, such as [FeH(H2)(dmpe)2][BPh4] and [MoH4(dppe)2] reducing 3,3-dimethylcyclopropene and cyclopropene. Products observed upon protonation and deuteration of several platinum-cyclopropene complexes are presented and a mechanism for their formation is proposed. 相似文献
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We present a database of 21 bond dissociation energies for breaking metal-ligand bonds. The molecules in the metal-ligand bond energy database are AgH, CoH, CoO+, CoOH+, CrCH3+, CuOH2+, FeH, Fe(CO)5, FeO, FeS, LiCl, LiO, MgO, MnCH3NiCH2+, Ni(CO)4, RhC, VCO+, VO, and VS. We have also created databases of metal-ligand bond lengths and atomic ionization potentials. The molecules used for bond lengths are AgH, BeO, CoH, CoO+, FeH, FeO, FeS, LiCl, LiO, MgO, RhC, VO, and VS and the ionization potentials are for the following atoms: C, Co, Cr, Cu, Ni, O, and V. The data were chosen based on their diversity and expected reliability, and they are used along with three previously developed databases (transition metal dimer bond energies and bond lengths and main-group molecular atomization energies) for assessing the accuracy of several kinds of density functionals. In particular, we report tests for 42 previously defined functionals: 2 local spin density approximation (LSDA) functionals, 14 generalized gradient approximation (GGA) methods, 13 hybrid GGA methods, 7 meta GGA methods, and 8 hybrid meta GGA methods. In addition to these functionals, we also examine the effectiveness of scaling the correlation energy by testing 13 functionals with scaled or no gradient-corrected correlation energy, and we find that functionals of this kind are more accurate for metal-metal and metal-ligand bonds than any of the functionals already in the literature. We also present a readjusted GGA and a hybrid GGA with parameters adjusted for metals. When we consider these 57 functionals for metal-ligand and metal-metal bond energies simultaneously with main-group atomization energies, atomic ionization potentials, and bond lengths we find that the most accurate functional is G96LYP, followed closely by MPWLYP1M (new in this article), XLYP, BLYP, and MOHLYP (also new in this article). Four of these five functionals have no Hartree-Fock exchange, and the other has only 5%. As a byproduct of this work we introduce a convenient diagnostic, called the B1 diagnostic, for ascertaining the multireference character in a bond. 相似文献
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R. Bruce King 《Coordination chemistry reviews》2010,254(11-12):1219
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Severin K 《Chemical communications (Cambridge, England)》2006,(37):3859-3867
Organometallic half-sandwich complexes of the late transition metals are versatile building blocks for supramolecular chemistry. They can be used to build metallamacrocyclic receptors and coordination cages, to study the adaptive behavior of dynamic combinatorial libraries and to generate indicator displacement assays for the detection of biologically interesting analytes such as peptides and aminoglycosides. 相似文献
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This review describes the chemistry of cyclophosphazene and polyphosphazene ligand systems and their transition and organometallic complexes. The structures of the ligands and the complexes are discussed. 相似文献
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Wolfgang A. Herrmann 《Journal of organometallic chemistry》1995,500(1-2):149-173
A systematic investigation of organorhenium- and organoosmium oxides, following the initial discovery of trioxo(η5-pentamethylcyclopentadienyl)rhenium(VII) in 1984 by Herrmann, Serrano and Bock, has yielded a plethora of high-oxidation-state organometallics. The key compound methyltrioxorhenium(VII) is now easily accessible and has displayed a surprisingly broad range of catalytic activities, most notably in olefin metathesis, olefin epoxidation, and aromatic oxidation (vitamin K3). In this context, general problems related to synthesis and reactivity, to structure and bonding, as well as to thermal and photochemical stability were tackled and solved. Organometallic oxides can also serve as structurally well-defined molecular or polymeric precursor compounds for the synthesis of inorganic oxides, the formation of rhenium trioxide being the first example to result from the polymer route. 相似文献
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Schindler A Heindl C Balázs G Gröger C Virovets AV Peresypkina EV Scheer M 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(3):829-835
Treatment of the pentaphosphaferrocene [Cp*Fe(η5‐P5)] with CuI halides in the presence of different templates leads to novel fullerene‐like spherical molecules that serve as hosts for the templates. If ferrocene is used as the template the 80‐vertex ball [Cp2Fe]@[{Cp*Fe(η5‐P5)}12{CuCl}20] ( 4 ), with an overall icosahedral C80 topological symmetry, is obtained. This result shows the ability of ferrocene to compete successfully with the internal template of the reaction system [Cp*Fe(η5‐P5)], although the 90‐vertex ball [{Cp*Fe(η5:η1:η1:η1:η1:η1‐P5)}12(CuCl)10(Cu2Cl3)5{Cu(CH3CN)2}5] ( 2 a ) containing pentaphosphaferrocene as a guest is also formed as a byproduct. With use of the triple‐decker sandwich complex [(CpCr)2(μ,η5‐As5)] as a template the reaction between [Cp*Fe(η5‐P5)] and CuBr leads to the 90‐vertex ball [(CpCr)2(μ,η5‐As5)]@[{Cp*Fe(η5‐P5)}12{CuBr}10{Cu2Br3}5{Cu(CH3CN)2}5] ( 6 ), in which the complete molecule acts as a template. However, if the corresponding reaction is instead carried out with CuCl, cleavage of the triple‐decker complex is found and the 80‐vertex ball [CpCr(η5‐As5)]@[{Cp*Fe(η5‐P5)}12{CuCl}20] ( 5 ) is obtained. This accommodates as its guest [CpCr(η5‐As5)], which has only 16 valence electrons in a triplet ground state and is not known as a free molecule. The triple‐decker sandwich complex [(CpCr)2(μ,η5‐As5)] requires 53.1 kcal mol?1 to undergo cleavage (as calculated by DFT methods) and therefore this reaction is clearly endothermic. All new products have been characterized by single‐crystal X‐ray crystallography. A favoured orientation of the guest molecules inside the host cages has been identified, which shows π???π stacking of the five‐membered rings (Cp and cyclo‐As5) of the guests and the cyclo‐P5 rings of the nanoballs of the hosts. 相似文献