Remarkable reactions of cyclooctatetraene diiron-bridging carbyne complexes with amino and amido compounds: nucleophilic addition to and breaking of the cyclooctatetraene ring

The reactions of the cationic, diiron-bridging carbyne complexes [Fe(2)(mu-CAr)(CO)(4)(eta(8)-C(8)H(8))]BF(4) (1, Ar=C(6)H(5); 2, Ar=p-CH(3)C(6)H(4); 3, Ar=p-CF(3)C(6)H(4)) with LiN(C(6)H(5))(2) in THF at low temperature gave novel N-nucleophilic-addition products, namely, the neutral, diiron-bridging carbyne complexes [Fe(2)(mu-CAr)(CO)(4)(eta(7)-C(8)H(8)N(C(6)H(5))(2))] (4, Ar=C(6)H(5); 5, Ar=p-CH(3)C(6)H(4); 6, Ar=p-CF(3)C(6)H(4))). Cationic bridging carbyne complexes 1-3 react with (C(2)H(5))(2)NH, (iC(3)H(7))(2)NH, and (C(6)H(11))(2)NH under the same conditions with ring cleavage of the COT ligand to produce the novel diiron-bridging carbene inner salts [Fe(2)[mu-C(Ar)C(8)H(8)NR(2)](CO)(4)] (7, Ar=C(6)H(5), R=C(2)H(5); 8, Ar=p-CH(3)C(6)H(4), R=C(2)H(5); 9, Ar=p-CF(3)C(6)H(4), R=C(2)H(5); 10, Ar=C(6)H(5), R=iC(3)H(7); 11, Ar=p-CH(3)C(6)H(4), R=iC(3)H(7); 12, Ar=p-CF(3)C(6)H(4), R=iC(3)H(7); 13, Ar=C(6)H(5), R=C(6)H(11); 14, Ar=p-CH(3)C(6)H(4), R=C(6)H(11), 15, Ar=p-CF(3)C(6)H(4), R=C(6)H(11)). Piperidine reacts similarly with cationic carbyne complex 3 to afford the corresponding bridging carbene inner salt [Fe(2)[mu-C(Ar)C(8)H(8)N(CH(2))(5)](CO)(4)] (16). Compound 9 was transformed into a new diiron-bridging carbene inner salt 17, the trans isomer of 9, by heating in benzene. Unexpectedly, the reaction of C(6)H(5)NH(2) with 2 gave a novel COT iron-carbene complex [Fe(2)[=C(C(6)H(4)CH(3)-p)NHC(6)H(5)](mu-CO)(CO)(3)(eta(8)-C(8)H(8))] (18). However, the analogous reactions of 2-naphthylamine with 2 and of p-CF(3)C(6)H(4)NH(2) with 3 produce novel chelated iron-carbene complexes [Fe(2)[=C(C(6)H(4)CH(3)-p)NC(10)H(7)](CO)(4)(eta(2):eta(3):eta(2)-C(8)H(9))] (19) and [Fe(2)[=C(C(6)H(4)CF(3)-p)NC(6)H(4)CF(3)-p](CO)(4)(eta(2):eta(3):eta(2)-C(8)H(9))] (20), respectively. Compound 18 can also be transformed into the analogous chelated iron-carbene complex [Fe(2)[=C(C(6)H(4)CH(3)-p)NC(6)H(5)](CO)(4)(eta(2):eta(3):eta(2)-C(8)H(9))] (21). The structures of complexes 6, 9, 15, 17, 18, and 21 have been established by X-ray diffraction studies.     

Relative kinetics of the radical addition of benzyl bromide to unsaturated compounds

The relative rate constants of the addition of the C₆H₅CH₂ radical to unsaturated compounds CH₂=CHX (X = C₄H₉, SiMe₃, CF₃, CO₂Me, CN) were determined under the conditions of initiation by the Fe(CO)₅ + DMF system or by benzoyl peroxide. Depending on the values of the relative addition rate constants, the monomers can be arranged into the following series (X): CF₃C₄H₉32Me5 + DMF system, the addition stage proceeds by a free radical mechanism.A. N. Nesmeyanov Institute of Heteroorganic Compounds, Russian Academy of Sciences, 117813 Moscow. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 9, pp. 2017–2022, September, 1992.     

Resonance Raman spectra of tris(acetylacetonato)iron(III) and ruthenium(III) complexes and their solvent effect

The resonance Raman spectra of tris(acetylacetonatoiron(III)) and ruthenium(III) complexes in various solvents and in water-acetonitrile (W-AN) mixtures were measured. The resonance Raman spectra of both complexes indicated peaks near 460 and around 1580 cm^–1. Thev(C-O) peak (around 1580 cm^–1) is shifted to low frequency with an increase in the dielectric constant _T of the solvents, whereas thev(M-O) (M=Fe and Ru, near 460 cm^–1) are constant, independent of _T. It implies that the C-O bond in the acac^– ligand is lengthened by the polarizability effect of the solvents, while both the Fe-O and Ru-O bonds, which are located in the inside of the complexes, are not influenced by the solvents indicating that the interaction does not depend on the properties of individual solvent molecules but on those of the aggregate.     

Über Oxide mit dem “Butterfly-Motiv”: Rb6[Fe2O5] und K6[Fe2O5]

New Oxides with the “Butterfly-Motive”: Rb₆[Fe₂O₅] and K₆[Fe₂O₅] Rb₆[Fe₂O₅] and K₆[Fe₂O₅] were obtained for the first time by annealing intimate mixtures of “Rb₆CdO₄” with CdO (molar ratio 1 : 1.1) and KO_0.48 with CdO (molar ratio 5.9 : 1) respectively in closed Fe-cylinders. Determination and refinement of the crystalstructure confirms the space group C2/m (four-circle-diffractometer data). Rb₆[Fe₂O₅]: Ag Kα , 720 out of 1220 Io(hkl), R = 9.68%, R_w = 6.09%; a = 718.9pm, b = 1183.1 pm, c = 695.4pm, β = 95.05°, Z = 2; K₆[Fe₂O₅]: MoKα , 1214 Out of 12141_o(hkl), R = 3.20070, R_w = 2.48%, a = 691.21 pm, b = 1142.78pm, c = 665.50pm, β = 93.82°, Z = 2. The binuclear unit [O₂FeOFeO₂]^6? already known to be planar with oxoferrates(II) now was observed to be angular here and closely related to Na₆[Be₂O₅].     

Triiron and Triruthenium Carbonyl Clusters Bearing Bridging Long Chain Diphosphine and Capping Chalcogenido Ligands

Treatment of Ru₃(CO)₁₂ with dpphSe₂ (dpph = 1,6-bis(diphenylphosphino)hexane) in refluxing toluene in the presence of Me₃NO afforded two new compounds, Ru₃(CO)₇(-CO)(₃-Se)(-dpph) (1) and Ru₃(CO)₇(₃-Se)₂(-dpph) (2). A similar reaction of Ru₃(CO)₁₂ with dpppeSe₂ (dpppe = 1,5-bis(diphenylphosphino)pentane) gave exclusively Ru₃(CO)₇(₃-Se)₂(-dpppe) (3). Treatment of Ru₃(CO)₁₂ with dpphS₂ and dpppeS₂ at 110°C in the presence of Me₃NO afforded Ru₃(CO)₇(₃-S)₂(-dpph) (4) and Ru₃(CO)₇(₃-S)₂(-dpppe) (5), respectively. Reactions of Fe₃(CO)₁₂ with dpphSe₂ and dpppeSe₂, under identical conditions, afforded Fe₃(CO)₇(₃-Se)₂(-dpph) (6) and Fe₃(CO)₇(₃-Se)₂(-dpppe) (7), respectively. Compounds 1–7 were characterized spectroscopically and the molecular structures of compounds 1–4 were determined by single crystal X-ray crystallography. The core of 1 contains an equilateral triangle of ruthenium atoms with one capping selenium, one bridging dpph, one doubly bridging carbonyl and seven terminal carbonyl ligands. Complexes 2–4 have a square-pyramidal structure with two metal and two chalcogenide atoms alternating in the basal plane and the third metal atom at the apex of the pyramid, and belong to the family of well-known nido clusters with seven skeletal electron pairs.     

Inter-ring η6⇌η5 haptotropic rearrangements of 18ē and 19ē (η5-pentamethylcyclopentadienyl)(η6-9-methylfluorenyl)iron complexes

New cationic complexes [(⁶-C₁₃H₁₀)Fe(⁵-Cp^*)]PF₆ and [(⁶-9-CH₃-C₁₃H₉)Fe(⁵-Cp^*)]PF₆ were obtained by the reaction of Cp^*Fe(CO)₂Br with fluorene and 9-methylfluorene, respectively. Deprotonation of these complexes byt-BuOK in THF affords zwitter-ionic compounds (⁶-C₁₃H₉)Fe(⁵-Cp^*) and (⁶-9-CH₃-C₁₃H₈)Fe(⁵-Cp^*) (A). WhenA is heated in nonane at 150 °C it undergoes ⁶⁵ inter-ring rearrangement with the formation of hexamethyldibenzoferrocene (B). The electrochemical behavior ofA andB was studied by cyclic voltammetry. One-electron reduction ofA andB to the corresponding radical anions induces inter-ring haptotropic rearrangementA ^.–B ^.–. The equilibrium in the 19 state is shifted to the ⁶-isomeric radical anionA ^.–, while in the 18 precursors, it shifts to the ⁵-isomerB.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 319–324, February, 1994.The authors are grateful to D. V. Zagorevskii (A. N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences) for recording and interpreting the mass spectra, and to A. A. Borisenko (Moscow State University) for recording the NMR spectra.This work was financially supported by the Russian Foundation for Basic Research (Grant 93-03-5209).     

From allylic alcohols to aldols by using iron carbonyls as catalysts: computational study on a novel tandem isomerization-aldolization reaction

The tandem isomerization-aldolization reaction between allyl alcohol and formaldehyde mediated by [Fe(CO)3] was studied with the density functional B3LYP method. Starting from the key [(enol)Fe(CO)3] complex, several reaction paths for the reaction with formaldehyde were explored. The results show that the most favorable reaction path involves first an enol/allyl alcohol ligand-exchange process followed by direct condensation of formaldehyde with the free enol. During this process, formation of the new C-C bond takes place simultaneously with a proton transfer between the enol and the aldehyde. Therefore, the role of [Fe(CO)3] is to catalyze the allyl alcohol to enol isomerization affording the free enol, which adds to the aldehyde in a carbonyl-ene type reaction. Similar results were obtained for the reaction between allyl alcohol and acetaldehyde.     

掺铁纳米TiO_2的制备及其光催化性能

以TiC l4为原料,采用微波加热与常规加热2步合成法制备掺铁纳米TiO2。用X射线粉末衍射(XRD)、透射电镜(TEM)、紫外可见吸收光谱(UV-V is)、光电子能谱(XPS)等测试技术对其进行了表征。结果表明,所制得的掺铁纳米TiO2是以锐钛矿为主相的混晶,平均粒径约为10 nm,适量Fe3+的掺杂能促进金红石相变,抑制锐钛矿晶粒的生长,使Ti2p电子结合能升高0.3 eV,并使TiO2吸光能力增强,带边吸收向可见光区移动。在UVA段(320~400 nm)光照下,通过对维生素VB12的光催化降解,发现掺入摩尔分数为0.5%的Fe3+的纳米TiO2能明显提高其光催化活性,使维生素B12的降解速率提高2.3倍。     

[NH3(CH2)5NH3][Fe2{O3PC(CH3)(OH)(PO3H)}2]@2H2O:一个新的二膦酸亚铁化合物的合成、结构与性质研究（英文）

通过水热合成得到一个新的有机二膦酸亚铁化合物[NH3(CH2)5NH3][Fe2Ⅱ(O3PC(CH3)(OH)(PO3H)}2]·2H2O,该化合物包含阴离子型共价双链[Fe2Ⅱ{O3PC(CH3)(OH)PO3H}2]n2n-,质子化的戊二胺和结晶水,双链之间通过强氢键构成一个开放型的骨架结构.另外,观察到亚铁离子之间存在弱铁磁性相互作用.     

Transition metal complexes in organic synthesis. Part 68: Iron-mediated total synthesis of mukonine and mukonidine by oxidative cyclization with air as the oxidizing agent

The oxidative cyclization of 5-(2-amino-5-methoxycarbonylphenyl)-substituted tricarbonyl[η⁴-cyclohexa-1,3-diene]iron complexes by air in protic medium provides the corresponding tricarbonyl[η⁴-4a,9a-dihydro-9H-carbazole]iron complexes. This procedure is applied to the total synthesis of the 3-methoxycarbonylcarbazole alkaloids mukonine and mukonidine.