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1.
We report the preparation of UFe(CO) 3− and OUFe(CO) 3− complexes using a laser-vaporization supersonic ion source in the gas phase. These compounds were mass-selected and characterized by infrared photodissociation spectroscopy and state-of-the-art quantum chemical studies. There are unprecedented triple bonds between U 6d/5f and Fe 3d orbitals, featuring one covalent σ bond and two Fe-to-U dative π bonds in both complexes. The uranium and iron elements are found to exist in unique formal U(I or III) and Fe(−II) oxidation states, respectively. These findings suggest that there may exist a whole family of stable df–d multiple-bonded f-element-transition-metal compounds that have not been fully recognized to date. 相似文献
2.
We perform in this work a comprehensive first-principles investigation on the geometric and electronic structures of Au(BO) 2 ? and Au(BS) 2 ? which are valent isoelectronic to the well-known Au(CN) 2 ? monoanion. Au(BO) 2 ? and Au(BS) 2 ? complexes prove to possess linear ground-state structures similar to Au(CN) 2 ? and the BO ? and BS ? ligands in them are found to be coordinated terminally via boron atoms to gold centers which are weakly negatively charged. Au–B bonds in Au(BO) 2 ? and Au(BS) 2 ? appear to have higher Wiberg bond indices (0.79 and 0.80) and more covalent components (60 and 53 %) than the corresponding values of Au–C interaction in Au(CN) 2 ? (0.67 and 39 %, respectively) at the same theoretical levels. Their Au–B bifurcation values of the electronic localization function also turn out to be higher than Au–C. These results strongly suggest that the Au–B bonds in Au(BO) 2 ? and Au(BS) 2 ? with multiple-bond character possess stronger covalent characters than Au–C in Au(CN) 2 ? . 相似文献
3.
121Sb Mössbauer spectra of the title complexes, whose isomer shifts are intermediate between the organoantimony(III) and organoantimony(V) compounds, suggest that considerable electrons are donated from hydrido ligand and Fe(CO) 4 fragments to the antimony atom. 相似文献
4.
Double deprotonation of the diamine 1,1′-( tBuCH 2NH)-ferrocene ( 1 -H 2) by alkaline-earth (Ae) or Eu II metal reagents gave the complexes 1 -Ae (Ae=Mg, Ca, Sr, Ba) and 1 -Eu. 1 -Mg crystallized as a monomer while the heavier complexes crystallized as dimers. The Fe⋅⋅⋅Mg distance in 1 -Mg is too long for a bonding interaction, but short Fe⋅⋅⋅Ae distances in 1 -Ca, 1 -Sr, and 1 -Ba clearly support intramolecular Fe⋅⋅⋅Ae bonding. Further evidence for interactions is provided by a tilting of the Cp rings and the related 1H NMR chemical-shift difference between the Cp α and β protons. While electrochemical studies are complicated by complex decomposition, UV/Vis spectral features of the complexes support Fe→Ae dative bonding. A comprehensive bonding analysis of all 1 -Ae complexes shows that the heavier species 1 -Ca, 1 -Sr, and 1 -Ba possess genuine Fe→Ae bonds which involve vacant d-orbitals of the alkaline-earth atoms and partially filled d-orbitals on Fe. In 1 -Mg, a weak Fe→Mg donation into vacant p-orbitals of the Mg atom is observed. 相似文献
5.
The ambiguous bonding situation of σ-E−H (E=Si, B) complexes in transition metal compounds has been rationalized by means of Density Functional Theory calculations. To this end, the combination of the Energy Decomposition Analysis (EDA) method and its Natural Orbital for Chemical Valance (NOCV) extension has been applied to representative complexes described in the literature where the possible η 1 versus η 2 coordination mode is not unambiguously defined. Our quantitative analyses, which complement previous data based on the application of the Quantum Theory of Atoms in Molecules (QTAIM) approach, indicate that there exists a continuum between genuine η 1 and η 2 modes depending mainly on the strength of the backdonation. Finally, we also applied this EDA-NOCV approach to related main-group species where the backdonation is minimal. 相似文献
6.
The clusters (μ 3-RP)Fe 3(CO) 10 ( 1) or (μ 3-RP)Fe 3(CO) 9(μ 2-H) 2 ( 2) can reversibly be transformed into the cluster anions [(μ 3-RP)Fe 3(CO) 9 (μ 2-H)] − ( 3) and [(μ 3-RP)Fe 3(CO) 9] 2− ( 4). The pyrophoric clusters 4 react with the divalent electrophile CH 2I 2 to give the complexes (μ 3-η 2-RP=CH 2)Fe 3(CO) 10 ( 5), which contain a cluster-stabilized phosphaalkene, RP=CH 2, as a ligand. With monovalent electrophiles R′X, such as Me 2SO 4, compound 4 (R = anisyl), yields, upon protolytic work-up, the complexes (μ 3-η 3-R′P-anisyl)Fe 3(CO) 9(μ 2-H) ( 6) in which the phosphorus-bound aryl residue of the μ 2-bridging phosphide ligand (R′P-anisyl) forms an η 2-coordination to the third iron atom of the cluster. The η 2-coordination of the aryl substituent may be reversibly released by two-electron ligands L under formation of (μ 2-R′P-anisyl)(μ 2-H)Fe 3(CO) 9L ( 7). In addition, the transformation sequence of 5 into 6 is accomplished by an H −, H + addition sequence. The experiments are documented by analytic and spectroscopic data as well as by X-ray analyses. 相似文献
7.
采用B3LYP和BP86方法,对铁羰基衍生物Fe(CO)_3(PR_3)_2和Fe(CO)_2(PR_3)_3(R=Cy,OPh和Ph)的几何和电子结构、成键特点以及热力学稳定性等进行了理论研究.计算结果表明,Fe(CO)_3(PR_3)_2的基态结构都为三角双锥的轴向双取代;对于Fe(CO)_2(PR_3)_3来说,三角双锥的腰部三取代(D_(3h))和腰部+轴向双取代(C_(2v))结构能量差别非常小.自然键轨道(NBO)分析显示,膦配体向羰基铁基团存在电荷转移,使得Fe—CO之间的共价作用有效增强.含膦配体铁羰基化合物Fe(CO)_3(PR_3)_2的第一膦配体解离能比第一羰基解离能低,预示Fe(CO)_3(PR_3)_2的反应活性比Fe(CO)_5有明显提高. 相似文献
8.
Abstarct The Cp) 2Ni 2Fe(CO) 3(µ 3-C 2H 2) and Cp) 2Ni 2Fe(CO) 3(µ 3-C 2H 2) (B) complexes have been synthesized and spectroscopically characterized. An accurate X-ray study and a comparison with related structures shows that the substituents of the alkyne ligands exert considerable effects on the bonding parameters.Crystal data for complex A, monoclinic space group P2 1/ n, a = 8.418(1), b = 15.779(2), c = 14,493(1) Å, = 91.64(1)°, Z = 4, 2753 observed reflections, R = 0.022; crystal data for complex B, monoclinic space group C2/ c, a = 16.2189(7), b = 7.445(3), c = 25.745(5) Å, = 103.74(3), Z=8, 1853 observed reflections, R = 0.051. 相似文献
9.
(η 4-Tropone)Fe(CO) 3 and (η 4-isoprene)Fe(CO) 3 form separable diastereoisomers on substitution of CO by (+)-(neomenthyl)PPh 2. In the tropone complex, diastereoisomer interconversion occurs by a 1,3-metal shift. The absolute configuration of the isoprene complex has been determined crystallographically. 相似文献
11.
The complex ion [Fe(CN) 6SO 3] 4− has been prepared in aqueous solution and as the zinc salt in the solid state. The electronic and IR spectra of the complex ion ( I) have been recorded. MO calculations have been performed to understand the electronic structure of complex I. The electronic spectra of I and hexacyanoferrate(II) [HCF(II)] have been calculated and compared with the experimental results for I, HCF(II) and HCF(III). The experimental and theoretical results suggest that the oxidation state of Fe in I is + 3 and not +2 and the SO 3 moiety is bonded to one of the nitrogen atoms of the cyano group. 相似文献
12.
Russian Journal of Applied Chemistry - Copolymerization of norbornene (NB), styrene (ST), and maleic anhydride (MA) catalyzed by Fe(acac)3-Al(i-Bu)3 has been investigated at different conditions... 相似文献
14.
The electrophoretic behavior of twenty anions has been studied on silica gel-G, titanium (IV) tungstate and silica gel-G- titanium (IV) tungstate admixture layers using 0.1 M solutions of oxalic acid, citric acid, tartaric acid, succinic acid and acetic acid as background electrolyte. The mechanism of migration is explained in terms of adsorption and the solubility of various sodium or potassium salts of the anions in water. Titanium (IV) tungstate behaves only as an adsorbent and not as an ion exchanger. Being a cation exchanger, there is no exchange phenomenon occurring with anions. The migration of halides increase linearly with an increase in the bare ion radii of these ions. Differential migration of the anions on silica gel-G layers led to binary, ternary and quaternary separations of similar anions such as F− – Cl− – Br− – I−, I− – IO3− – IO4−, BrO3− – IO3− and Fe(CN)63− – Fe(CN)64−. The two cyanoferrate ions are separated from industrial waste water and from fixer and bleach solutions. The migration of anions has also been found to be in accordance with their lyotropic numbers. 相似文献
15.
The alkaline earth metals (M=Mg, Ca, Sr, and Ba) exhibit a +2 oxidation state in nearly all known stable compounds, but M I dimeric complexes with M−M bonding, [M 2(en) 2] 2+, (en=ethylenediamine) of all these metals can be stabilized within the galleries of donor-type graphite intercalation compounds (GICs). These metals can also form GICs with more conventional metal (II) ion complexes, [M(en) 2] 2+. Here, the facile interconversion between dimeric-M I and monomeric-M II intercalates upon the addition/removal of en are reported. Thermogravimetry, powder X-ray diffraction, and pair distribution function analysis of total scattering data support the presence of either [M 2(en) 2] 2+ or [M(en) 2] 2+ guests. This phase conversion requires coupling graphene and metal redox centers, with associated reversible M−M bond formation within graphene galleries. This chemistry allows the facile isolation of unusual oxidation states, reveals M 0→M 2+ reaction pathways, and present new opportunities in the design of hybrid conversion/intercalation materials for applications such as charge storage. 相似文献
16.
Reactions of [Fe 2S 2(CO) 6] 2− ( 3) with [Cl 2FeS 2MS 2] 2− [M = Mo ( 4) or W ( 6)] and [Cl 2FeS 2VS 2FeCl 2] 3− ( 8) in acetonitrile-THF solutions afford the new clusters [MFe 3S 6(CO) 6] 2− (M = Mo ( 5) or W ( 7)] and [VFe 6S 8(CO) 12] 3− ( 9). (Et 4N) 2 ( 5) crystallizes in orthorhombic space group Pbcn with a = 15.314(7) Å, b = 16.627(6) Å, c = 29.971(13) Å, and Z = 8. Cluster 5 is formed by displacement of chloride from 4 by 3 to yield a species with the [Fe 2(μ 3-S) 2Fe(μ 2-S) 2MoS 2] 2− core arrangement containing one Fe(II) and Mo(VI) in distorted tetrahedral sites. Similar structures are proposed for 7 and 9, with the latter containing two 3 ligands bound to the [VFe 2S 4] 1+ core of 8. Treatment of 5 with RSSR results in oxidative decarbonylation and formation of [Mo 2Fe 6S 8(S 2) 2(SR) 6] 4− ( 10) (R = p-C 6H 4Cl or p-C 6H 4Br), which consists of two [MoFe 3(μ 3-S) 4] 3+ cubane-type subclusters bridged by two μ 2-η 3-S 22− groups. Cluster 10 was also obtained in a direct-assembly system consisting of [MoS 4] 2− + 3FeCl 3+ S 22− + 7RS − in methanol. Evidence is presented that the solid-state structure of 10 is maintained in solution. The redox change [MoFe 3(μ 2-S) 2(μ 3-S) 2S 2] 2− ( 5) → [MoFe 3(μ 3-S) 4(S 2)] 1+ ( 10) is described as an oxidatively induced core internal conversion in which there is net Fe and S oxidation and Mo reduction. It is argued that the reduction of tetrahedral Mo(VI) to or near Mo(III), stabilized in a six-coordinate site, is a significant factor in the formation of the cubane structure. The formation of the cubane cluster [VFe 3S 4Cl 3(DMF) 3] 1− from 8 and FeCl 2 is similarly promoted by the reduction of tetrahedral V(V) to or near V(III). The syntheses of 5, 7, 9 and 10 illustrate the utility of 3 as a cluster precursor. 相似文献
17.
A series of bis(σ)-borane complexes of Group 6 transition metals were prepared by direct dihydroborane coordination to the metal center. Reaction of [M(CO) 3(PCy 3) 2] and two dihydroboranes [DurBH 2] and [(Me 3Si) 2NBH 2] (Dur=2,3,5,6-Me 4C 6H) yielded bis(σ)-borane complexes fac-[M(CO) 3(PCy 3){η 2-(H 2BR)}] (R=Dur; 1 : M=Cr, 2 : M=W; R=N(SiMe 3) 2; 3 : M=Cr, 4 : M=W). In the case of molybdenum, we have isolated an arene complex ( 5 ) with [DurBH 2] in which the Dur group acts as a η 6-bound ligand, and with [(Me 3Si) 2NBH 2] a similar bis(σ)-borane complex was isolated, cis, trans-[Mo(CO) 2(PCy 3) 2{η 2-(H 2BN(SiMe 3) 2}] ( 6 ), with a different pattern of auxiliary ligands. The complexes were investigated by multinuclear NMR spectroscopy, mass spectrometry, X-ray diffraction analysis, and computational methods. Quantum theory of atoms in molecules (QTAIM) calculations demonstrated that the borane complexes may be described as pure bis(σ)-borane complexes rather than elongated or stretched examples given that the calculations do not show the presence of a ring-critical point (RCP) at the ring formed by the interactions of the B−H with metal center. 相似文献
18.
A specially designed thermo-electrochemical calorimeter was applied to measure the electrochemical Peltier heats (EPH) of Fe(CN) 6 3?/4? system at 295.15 K. The curves of the electrode potential changes and temperature changes against time for Fe(CN) 6 3?/4? couple with five groups of different concentrations were obtained under the condition of various constant-current polarizations. The EPH values for the considered electrode reaction are determined to be ?41.31, ?42.73, ?44.28, ?45.87, and ?46.65 kJ mol ?1 at the respective concentrations of 0.125, 0.175, 0.225, 0.275, and 0.300 mol dm ?3; and the EPH and the apparent enthalpy change corresponding to the infinite dilution to be ?37.42 and ?84.10 kJ mol ?1 at 295.15 K, respectively. 相似文献
19.
We report a new antiferromagnetic radical-anion salt (RAS) formed from 7,7,8,8-tetracyanquinonedimethane (TCNQ) anion and 2-amino-5-chloro-pyridine cation with the composition of (N−CH 3−2-NH 2−5Cl−Py)(TCNQ)(CH 3CN). The crystallographic data indicates the formation of (TCNQ) 2.− radical-anion π-dimers in the synthesized RAS. Unrestricted density functional theory calculations show that the formed π-dimers characterize with strong π-stacking “pancake” interactions, resulting in high electronic coupling, enabling efficient charge transfer properties, but π-dimers cannot be stable in the isolated conditions as a result of strong Coulomb repulsions. In a crystal, where (TCNQ) 2.− π-dimers bound in the endless chainlets via supramolecular bonds with (N−CH 3−2-NH 2−5-Cl−Py) + cations, the repulsion forces are screened, allowing for specific parallel π-stacking interactions and stable radical-anion dimers formation. Measurements of magnetic susceptibility and magnetization confirm antiferromagnetic properties of RAS, what is in line with the higher stability of ground singlet state of the radical-anion pair, calculated by means of the DFT. Therefore, the reported radical-anion (N−CH 3−2-NH 2−5Cl−Py)(TCNQ)(CH 3CN) solvate has promising applications in novel magnetics with supramolecular structures. 相似文献
20.
The precipitate formed by the reaction of benzalazine with Fe 3(CO) 12 yields the triangular clusters Fe 3(PhCH 2N)(CO) 10 and HFe 3(PhCHN)(CO) 9 when decomposed by concentrated hydrochloric and phosphorous acids, respectively. The structure of μ-( o-C 6H 4CH 2NNCHPh)Fe 2(CO) 6, a product obtained from the benzalazine and Fe 3(CO) 12 reaction, is discussed. 相似文献
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