羰基过渡金属异核原子簇[(μ-SHgFe~Co(CO|)~9.(μ-CI)]~2的合成及晶体结构

本文报道了羰基异核原子簇, [(μ2-)HgFeCo(CO)~9(μ-CI)]~2的合成及晶体结构。化合物由(μ-S)HgFeCo(CO)~9(μ-CI)双聚而成。双聚分子具有c~2h对称性。在Fe-Fe, Fe-Co之间存在明显的金属-金属键。三核簇中的两个铁原子作为双齿配体与Hg原子配位。并通过HgS二聚形成双三角型簇合物。     

羰基过渡金属异核原子簇[(μ-SHgFe~Co(CO|)~9.(μ-CI)]~2的合成及晶体结构

本文报道了羰基异核原子簇, [(μ2-)HgFeCo(CO)~9(μ-CI)]~2的合成及晶体结构。化合物由(μ-S)HgFeCo(CO)~9(μ-CI)双聚而成。双聚分子具有c~2h对称性。在Fe-Fe, Fe-Co之间存在明显的金属-金属键。三核簇中的两个铁原子作为双齿配体与Hg原子配位。并通过HgS二聚形成双三角型簇合物。     

铁钴三核原子簇氢化物HFe2Co(CO)9PR和HFe2Co(CO)9Se的合成

在THF 中反应, 合成了以有机膦作μ3-配位体的新型铁钴三核原子簇羰基氢化物HFe2Co(CO)9PR.又用高压法合成FeCo2(CO)2Se, 它与Na2[Fe(CO)4] 在THE 中反应, 得到另一个以硒作μ3-配位体的新型铁钴三核原子簇羰基氢化物式电离成-价阴离子, 再与反应生成     

钼铁硫原子簇化合物的结构规则

本文将过渡金属原子簇化合物的9N-L结构规则, 用于讨论Mo-Fe-S原子簇化合物, 得到了它们的结构和自旋性质之间的关系,推得的理论最大自旋值与实验事实吻合. 进而, 对各种Mo-Fe-S原子簇化合物的典型分子或模型分子, 进行了EHMO量子化学计算, 得到了与上述讨论相一致的结果, 进 一步揭示和验证了上述讨论的本质.     

[Mo2O2S2(S2)2][2-]的振动光谱研究

本文测定了原子簇化合物[Mo2O2S2(S2)2][2-]的红外和拉曼光谱,并在乙腈溶液中测得其共振拉曼光谱和退偏振比。利用X光晶体结构数据,对此阴离子的伸缩振动作了简化的正则坐标分析计算。所得结果可以帮助分析和归属一些Mo-Fe-S原子簇化合物的振动光谱。     

一种新型的混合金属原子簇化合物(η^5-C5H5)4Mo4Fe2-(μ3-S)5(CO)5的合成和晶体结构

用(η^5-C5H5)2Mo2(CO)6和Fe3S2(CO)9在甲苯中的反应制备了一种新型混合金属原子簇化合物(η^5-C5H5)4Mo4Fe2-(μ3-S)5(CO)5.并用X-射线结构分析测定了它的晶体结构和分子结构.结果表明原子簇的骨架是由[FeMo3S4]的类立方烷孪合[MoFe2S]的三角锥,它们之间共用一个Fe原子.     

(μ-巯基)(μ-烃硫)六羰基二铁对不饱和碳原子的亲核取代反应

通过(μ-巯基)(μ-烃硫)六碳基二铁与酰卤的亲核取代反应,合成了通式为(μ-CH3COS)(μ-RS)Fe2(CO)6的九个铁硫原子簇络合物.经元素分析, IR及^1H NMR光谱证实了所有这些络合物的结构和构象. 并简要地讨论了酰氯的反应活性及三乙胺在反应中的作用.     

三核钼原子簇化合物的研究进展

本文结合作者等人的研究工作,总结了迄今文献上所发表的成果,包括三核钼原子簇化台物的各种合成方法,结构类型,并用简化的量子化学方法对几种主要结构类型簇胳的金属-金属键加以分析。在这基础上,对几种主要性质加以讨论。     

[Mo2FeS8O2][Et4N]3CH3CN原子簇化合物的晶体结构

[Mo_2FeS_8O_2][Et_4N]_3·CH_3CN晶体属三斜晶系,PI空间群.α=9.998(1)A,b=13.868(3)A,c=16.796(3)A,α=74.66(2)°,β=85.41(1)°,ν=72.21(1)°,Ζ=2.结构参数经块矩阵最小二乘法精修后,最后的偏离因子R=0.037,R_w=0.034.平均键长Mo—Fe为2.722A,Mo—S为2.358A,Fe—S为2.244A,Mo—O为1.697A.结果表明:标题化合物是一个结构新颖的原子簇化合物.它是由一个三价原子簇阴离子与三个一价的乙基季铵阳离子靠静电引力结合在一起,又溶剂合一个乙氰分子的原子簇化合物而形成.     

原子簇化合物中钒的光度测定法

过渡金属原子簇化合物是近年来化学领域研究的热点.其中含钒原子簇化合物与生化中的金属酶有密切关系,因此提出了原子簇化合物中钒的分析测定新课题.由于钒原子簇化合物不易合成,提供测试量很少,试样中含钒及干扰金属量较高,需进行微量分析.过氧化氢存在下2(5-溴-吡啶偶氮)-5-二乙氨基苯酚(简称5-BrPADAP)与钒的三元络合物光度法已有研究并应用于钢铁分析,在该工作基础上,本文加入非离子型表面活性剂吐温-80增溶,以提高络合物的稳定性.由于原子簇化合物中常见元素W,Ti,     

铁硫原子簇配合物(μ-MeS)[μ-Fe(CO)2CpS]Fe2(CO)6的晶体和分子结构

标题化合物为单斜晶系, 空间群P2_1/n, 晶胞参数:a=0.79099(7), b=1.0774(1), c=2.2531(4) nm, γ=92.91(1)°, Z=4。本文讨论了铁硫原子簇配合物(μ-R~1S)(μ-R~2S)Fe_2(CO)_6中, 取代基R~1, R~2大小对化合物结构的影响。当R为较大的基团, 如PPh_3或Fe(CO)_2Cp时, 平均Fe-S键增长。而且簇骨架外的Fe-S键增长比簇骨架内的Fe-S键增长更加明显, 说明Fe-Fe键有稳定骨架的作用。R基团的大小对簇骨架内的扭角S-Fe-Fe-S也有明显的影响。标题化合物中R~1, R~2取代基采取(a,e)构象排布, 有利于缓解取代基间的空间排斥作用。     

一系列多核Mo(W)-Cu(Ag)-S簇合物的低热固相合成、成簇规律和机理的研究

本文报道了一系列多核Mo(W)-Cu(Ag)-S族合物的低热固相合成, 发现硫代钼(钨)酸铵与铜(银)的成簇规律主要与固相反应温度密切相关, 提出了四核至七核Mo(W)-Cu(Ag)-S簇合物的可能成簇机理。     

Application of a universal force field to mixed Fe/Mo-S/Se cubane and heterocubane clusters. 1. Substitution of sulfur by selenium in the series [Fe4X4(YCH3)4]2-; X = S/Se and Y = S/Se

A series of Fe-S and Fe-Se cubane clusters containing all four combinations of the general formula [Fe(4)X(4)(Y-CH(3))(4)](2)(-) (X = S/Se, Y = S/Se) is investigated with FTIR and Raman spectroscopy. The terminally selenolate coordinated clusters (Y = Se) are prepared by a new synthetic route. All four cluster compounds are structurally characterized by X-ray single-crystal structure determination. Infrared and Raman spectra of all compounds are presented and interpreted with normal coordinate analysis. The corresponding force fields are based on that developed for the Fe(4)S(4)-benzyl cluster (Czernuszewicz, R. S.; Macor, K. A.; Johnson, M. K.; Gewirth, A.; Spiro, T. G. J. Am.Chem. Soc. 1987, 109, 7178-7187). An empirical procedure is presented to convert Fe-S into Fe-Se force constants. Only minor changes in force constants are found upon S --> Se exchange, reflecting the similarity of the Fe-S and Fe-Se bonds. The drastic frequency shifts in the metal-ligand region observed upon substitution of sulfur by selenium are, therefore, primarily due to the corresponding mass changes.     

双三苯膦铁硫原子簇配合物(μ-i-C3H7S)(μ-PhCH2S)-Fe2(CO)4(PPh3)2的合成及晶体结构

通过(μ-i-C3H7S)(μ-PhCH2S)Fe2(CO)6和三苯膦在甲苯中回流反应6h, 制得了三苯膦双取代配合物(μ-i-C3H7S)(μ-PhCH2S)Fe2(CO)4(PPh3)2(1), 并用X射线衍射技术测得其单晶结构. 晶体属三斜晶系, 空间群为PI. 晶胞参数: a=10.268(4),b=20.289(1), c=22.799(5)埃; a=94.73(1)°, β=102.98(2)°, γ=89.93(1)°;V=4610.5埃^3, Z=4, Dc=1.36g/cm^3. 晶体结构用直接法(MULTAN 82)测定, 采用块矩阵最小二乘法进行最终结构精化, 最后偏离因子R=0.059, Rw=0.068. 单晶X射线分析表明, 配合物1的簇核是由两个铁原子和两个硫原子组成的蝴蝶式结构; 两个三苯膦配体处于铁-铁弯键的反位; 异丙基和苄基分别以6键与硫相连.     

Secondary structure analysis of peptides with relevance to iron–sulfur cluster nesting

Peptides coordinated to iron–sulfur clusters, referred to as maquettes, represent a synthetic strategy for constructing biomimetic models of iron–sulfur metalloproteins. These maquettes have been successfully employed as building blocks of engineered heme-containing proteins with electron-transfer functionality; however, they have yet to be explored in reactivity studies. The concept of iron–sulfur nesting in peptides is a leading hypothesis in Origins-of-Life research as a plausible path to bridge the discontinuity between prebiotic chemical transformations and extant enzyme catalysis. Based on past biomimetic and biochemical research, we put forward a mechanism of maquette reconstitution that guides our development of computational tools and methodologies. In this study, we examined a key feature of the first stage of maquette formation, which is the secondary structure of aqueous peptide models using molecular dynamics simulations based on the AMBER99SB empirical force field. We compared and contrasted S…S distances, [2Fe-2S] and [4Fe-4S] nests, and peptide conformations via Ramachandran plots for dissolved Cys and Gly amino acids, the CGGCGGC 7-mer, and the GGCGGGCGGCGGW 16-mer peptide. Analytical tools were developed for following the evolution of secondary structural features related to [Fe-S] cluster nesting along 100 ns trajectories. Simulations demonstrated the omnipresence of peptide nests for preformed [2Fe-2S] clusters; however, [4Fe-4S] cluster nests were observed only for the 16-mer peptide with lifetimes of a few nanoseconds. The origin of the [4Fe-4S] nest and its stability was linked to a “kinked-ribbon” peptide conformation. Our computational approach lays the foundation for transitioning into subsequent stages of maquette reconstitution, those being the formation of iron ion/iron–sulfur coordinated peptides. © 2018 Wiley Periodicals, Inc.     

Extended X-ray absorption fine structure and nuclear resonance vibrational spectroscopy reveal that NifB-co, a FeMo-co precursor, comprises a 6Fe core with an interstitial light atom

NifB-co, an Fe-S cluster produced by the enzyme NifB, is an intermediate on the biosynthetic pathway to the iron molybdenum cofactor (FeMo-co) of nitrogenase. We have used Fe K-edge extended X-ray absorption fine structure (EXAFS) spectroscopy together with (57)Fe nuclear resonance vibrational spectroscopy (NRVS) to probe the structure of NifB-co while bound to the NifX protein from Azotobacter vinelandii. The spectra have been interpreted in part by comparison with data for the completed FeMo-co attached to the NafY carrier protein: the NafY:FeMo-co complex. EXAFS analysis of the NifX:NifB-co complex yields an average Fe-S distance of 2.26 A and average Fe-Fe distances of 2.66 and 3.74 A. Search profile analyses reveal the presence of a single Fe-X (X = C, N, or O) interaction at 2.04 A, compared to a 2.00 A Fe-X interaction found in the NafY:FeMo-co EXAFS. This suggests that the interstitial light atom (X) proposed to be present in FeMo-co has already inserted at the NifB-co stage of biosynthesis. The NRVS exhibits strong bands from Fe-S stretching modes peaking around 270, 315, 385, and 408 cm(-1). Additional intensity at approximately 185-200 cm(-1) is interpreted as a set of cluster "breathing" modes similar to those seen for the FeMo-cofactor. The strength and location of these modes also suggest that the FeMo-co interstitial light atom seen in the crystal structure is already in place in NifB-co. Both the EXAFS and NRVS data for NifX:NifB-co are best simulated using a Fe 6S 9X trigonal prism structure analogous to the 6Fe core of FeMo-co, although a 7Fe structure made by capping one trigonal 3S terminus with Fe cannot be ruled out. The results are consistent with the conclusion that the interstitial light atom is already present at an early stage in FeMo-co biosynthesis prior to the incorporation of Mo and R-homocitrate.     

醋酸乙烯酯基桥连铁硫配合物(σ,π-μ-CH3CO2C=CH2)(μ-RS)Fe2CO)6的制备及结构鉴定

本文报道乙酰氯同[μ-CO)(μ-RS)Fe2(CO]Et3NH相作用生成了标题化合物, 除用碳氢分析, IR, 'HNMR及X衍射技术表征这类配合物的结构和构象外, 还对形成此类产物的过程进行了初步讨论。     

Unit Construction in the Formation of Metal Clusters──Investigation on the Metal Cluster Compounds Containing Fe_2S_2(CO)_6-units

1INTRODUCTIONThechemistryofMo--S,Fe--SandMo-Fe--Sclustercomplexeshasincreasinglyinterestedchemistsandbioinorganicchemistssincetheexistenceofmetal-sulfurbondinginmetalenzymes,especiallytheFe--Mo--Sclusterastheactivecenterinni-trogenase,wasdiscovered.Recently,aninterestingFe--SstructuralunitFeZSZ(CO),t'3,hasbeeningoodglancesofpeopleandthechemistryofthemetalclustercompoundscontainingFe,S,(CO),-unitshasbeenfocusedbygreatattentionbecausei)FeZSZ(CO)6isanironsourceforthesynthesisofMo-…     

Electrical Conduction of Some Fe3S3 Ring Compounds

M3S3 cluster six-membered ring compounds are very interesting compounds liking aromatic benzene, and Cu, Pd, B and so on can also form M3S3 cluster besides Fe. [1,2] In recent years electrical conduction of some metal com plexes has been studied. [3,4] The study of electrical conduction through DNA molecules has illustrated that DNA is a semiconductor, but its principle of electrical conduction has not been revealed. [5,6] Electrical conduction of artificial synthesized Fe-S cluster compounds has not been reported. We hope to infer the function on electrical conduction of metal active centers of iron-sulfur proteins through study of electrical conduction of Fe3S3 ring compounds, paving the way for the discovery of new advanced biological functional materials.