Reactions of the unsaturated anion [Re3(μ-H)4(CO)10]− with phosphines. Synthesis of the anions [Re3(μ-H)2(CO)10(PR3)2]−, and crystal structure of [NEt4][Re3(μ-H)2(CO)10(PPh3)2]

The reaction of the unsaturated cluster anion [Re₃(μ-H)₄(CO)₁₀]⁻ with tertiary phosphines at room temperature results in the substitution of two hydride ligands (eliminated as H₂) by two PR₃ ligands, leading to saturated [Re₃(μ-H)₂(CO)₁₀-(PR₃)₂]⁻ compounds. A single crystal X-ray diffraction study of the PPh₃ derivative revealed that the two phosphines occupy non-equivalent equatorial coordination sites on the triangular cluster. The rate of the reaction greatly increases with increase of the basicity of the phosphine.     

Novel Reaction of the [HFe3(CO)11]− reagent with alkynes: A new synthesis of cyclobutenediones

Reaction of the [HFe₃(CO)₁₁]⁻ species generated in situ using Fe(CO)₅ and NaBH₄/CH₃COOH in THF with alkynes, followed by CuCl₂.2H₂O oxidation leads to the corresponding cyclobutenediones in 60–73% yields.     

Synthesis and Structure of Os5(μ-Cl)2(CO)16(CNBut)2: A Cluster with a “Hook” Arrangement of Metal Atoms

Os₅(-X)₂(CO)₁₆(L)₂ (X=Cl, 1, Br; L=CNBu ^t ) clusters have been prepared by the reaction of Os₃(-X)₂(CO)₁₀ with Os(CO)₄(L) at a 1:2 molar ratio in solution at 60°C. The crystal structure of the chloro compound reveals that the Os₃(-Cl)₂ fragment present in the precursory cluster is maintained in 1 with a coordination site cis to the Cl ligands occupied by the unusual Os(CO)₄Os(CO)₃(L)₂ unit. The resulting hook arrangement of the Os₅ skeleton has not been observed previously. The OsOs lengths are in the range 2.8384(6)–2.8999(6)Å. The OsOs bonds associated with the pendant fragment are both considered dative bonds.     

An Improved Synthesis for Novel Hexaruthenium Cluster Compound Bearing Two Quadruply-Bridging CO Ligands: Synthesis, Characterization, and X-Ray Structural Analysis of Ru6(CO)12(μ3-H)(μ-CO) (μ4-η2-CO)2[η5-C5H4(SiMe3)]

The hexaruthenium cluster compound Ru₆(₃-H)(CO)₁₅[C₅H₄(SiMe₃)] (2), possessing two ₄-²-CO ligands and with the Ru[C₅H₄(SiMe₃)] fragment located at the apex of the central tetrahedral framework, was prepared in low yield by refluxing a toluene solution of C₅H₅(SiMe₃) with excess Ru₃(CO)₁₂. This unique complex was characterized by spectroscopic methods and by X-ray structural analysis. The possible mechanism leading to its formation is discussed.     

Reaction of the heteronuclear cluster RuOs3(μ-H)2(CO)13 with azulenes

Reaction of the heteronuclear cluster RuOs₃(μ-H)₂(CO)₁₃ (1) with azulene under thermal activation afforded the novel clusters RuOs₃(μ-H)(CO)₉(μ₃,η⁵:η²:η²-C₁₀H₉) (3) and Ru₂Os₃(μ-H)₂(CO)₁₃(μ-CO)(μ₃,η⁵:σ²-C₁₀H₈) (5a), with 4,6,8-trimethylazulene to give RuOs₃(μ-H)(CO)₈(μ-CO)(μ,η⁵:η⁴-C₁₀H₆Me₃) (4) and Ru₂Os₃(μ-H)₂(CO)₁₃(μ-CO)(μ₃,η⁵:σ²-C₁₀H₅Me₃) (5b), and with guaiazulene to give Ru₂Os₃(CO)₁₁(μ₃,η⁵:η³:η³-C₁₀H₅Me₂ⁱPr) (6), respectively. In 3–5, cluster-to-ligand hydrogen transfer appears to have taken place, with the organic moiety capping a trimetallic face in 3, bridging a metal–metal bond in 4 and via a μ₃,η⁵:σ² bonding mode in 5a and 5b. Cluster 6 contains a trigonal bipyramidal metal framework with the guaiazulene ligand over a triangular metal face. All five clusters have been completely characterised, including by single-crystal X-ray diffraction analysis.     

The reaction of CpWMe(CO)3 with LiEt3BH. Formation of the formyl complex trans-[CpWMe(CHO)(CO)2]− and the (hydrido)(acyl) complex trans-[CpWH(COMe)(CO)2]−

Addition of LiEt₃BH to CpWMe(CO)₃ results in consecutive formation of trans-[CpWMe(CHO)(CO)₂]⁻ (some of which exists in solution as two rotamers of a BEt₃ adduct) and trans[CpWH(COMe)(CO)₂]⁻. Reaction of the latter with CHI₃ and subsequent treatment of the product with either (i) Me₃SiCl, followed by filtration through SiO₂ or (ii) Me₃OBF₄ gives hydroxy- or methoxy-carbenes CpWI[C(OR)Me](CO)₂ (R H or Me), respectively.     

Synthesis,Characterization and Thermostability of a Novel Pb(Ⅱ) Coordination Polymer with Mixed Ligands

A novel mixed-ligand coordination polymer [Pb(phen)(NNDS)(H2O)]n·n H2O(1) was obtained from the reaction of 1,10-phenanthroine(phen), Pb(OAc)2 and sodium 1-nitroso-2-naphthol-3,6-disulfonate(Na2NNDS) in a mixed solvent. The complex was characterized by elemental analysis, IR and X-ray single-crystal diffraction. Crystal data for 1: monoclinic, space group P21/c, a = 11.5835(9), b = 14.6334(11), c = 13.9030(11) ?, β = 98.4180(10)o, V = 2331.3(3) ?3, Z = 4, Mr = 754.70, Dc = 2.150 mg/m3, μ = 7.483 mm-1, F(000) = 1456, the final R = 0.0430 and w R = 0.0841 for 4221 observed reflections with I 2σ(I). The Pb(II) center is coordinated by six O and two N atoms showing a distorted dodecahedron configuration. The multidentate ligand of NNDS dianion exhibits peculiar coordination mode, and the two O atoms of two sulfonate anions bridge two Pb(II) cations into a dimer, and the O atom of nitroso group links the other dimer into 2D sheets extending in the [011] plane. There exist significant π-π stacking interactions between adjacent phen and NNDS. The 3D network is formed by 2D sheets interlinked by hydrogen bonds and π-π stacking interactions. The thermostability of 1 was investigated by TG and DSC.     

Modeling the Signatures of Hydrides in Metalloenzymes: ENDOR Analysis of a Di-iron Fe(μ-NH)(μ-H)Fe Core

The application of 35 GHz pulsed EPR and ENDOR spectroscopies has established that the biomimetic model complex L(3)Fe(μ-NH)(μ-H)FeL(3) (L(3) = [PhB(CH(2)PPh(2))(3)](-)) complex, 3, is a novel S = (1)/(2) type-III mixed-valence di-iron II/III species, in which the unpaired electron is shared equally between the two iron centers. (1,2)H and (14,15)N ENDOR measurements of the bridging imide are consistent with an allyl radical molecular orbital model for the two bridging ligands. Both the (μ-H) and the proton of the (μ-NH) of the crystallographically characterized 3 show the proposed signature of a 'bridging' hydride that is essentially equidistant between two 'anchor' metal ions: a rhombic dipolar interaction tensor, T ≈ [T, -T, 0]. The point-dipole model for describing the anisotropic interaction of a bridging H as the sum of the point-dipole couplings to the 'anchor' metal ions reproduces this signature with high accuracy, as well as the axial tensor of a terminal hydride, T ≈ [-T, -T, 2T], thus validating both the model and the signatures. This validation in turn lends strong support to the assignment, based on such a point-dipole analysis, that the molybdenum-iron cofactor of nitrogenase contains two [Fe-H(-)-Fe] bridging-hydride fragments in the catalytic intermediate that has accumulated four reducing equivalents (E(4)). Analysis further reveals a complementary similarity between the isotropic hyperfine couplings for the bridging hydrides in 3 and E(4). This study provides a foundation for spectroscopic study of hydrides in a variety of reducing metalloenzymes in addition to nitrogenase.     

Tetrarhena-heterocycle from the palladium-catalyzed dimerization of Re2(CO)8(μ-SbPh2)(μ-H) exhibits an unusual host-guest behavior

The six-membered heavy atom heterocycles [Re(2)(CO)(8)(μ-SbPh(2))(μ-H)](2), 5, and Pd[Re(2)(CO)(8)(μ-SbPh(2))(μ-H)](2), 7, have been prepared by the palladium-catalyzed ring-opening cyclo-dimerization of the three-membered heterocycle Re(2)(CO)(8)(μ-SbPh(2))(μ-H), 3. The palladium atom that lies in the center of the heterocycle 7 was removed to yield 5. The palladium removal was found to be partially reversible leading to an unusual example of host-guest behavior. A related dipalladium complex Pd(2)Re(4)(CO)(16)(μ(4)-SbPh)(μ(3)-SbPh(2))(μ-Ph)(μ-H)(2), 6, was also formed in these reactions of palladium with 3.     

Synthesis and Characterization of the cis-Dicyanoiron(Ⅱ) Building Block and Its Interactions with Selected Metal Ions

In this work, a cis-dicyanoiron(Ⅱ) building block, cis-Fe~(Ⅱ)(bpy)_2(CN)_2(1, bpy = 2,2?-bipyridine), has been prepared and fully characterized by IR, electronic absorption spectra, elemental analysis, cyclic voltammetry and single-crystal X-ray diffraction analysis. The interactions of complex 1 with selected metal ions, such as Cu(Ⅱ), Fe(Ⅲ), Pb(Ⅱ), Fe(Ⅱ), Cr(Ⅲ), Cd(Ⅱ), Co(Ⅱ), Zn(Ⅱ), Ni(Ⅱ) and Mn(Ⅱ), were investigated employing electronic absorption spectroscopy. The electronic absorption spectroscopy indicates Cu(Ⅱ), Fe(Ⅲ), Cr(Ⅲ), Cd(Ⅱ), Co(Ⅱ), Zn(Ⅱ) and Ni(Ⅱ) ions steadily coordinate with 1 via cyanide, respectively. Fluorescent emission intensity of 1 increased upon the addition of Zn(Ⅱ) ion, quenched by adding ions Cu(Ⅱ), Fe(Ⅲ) and Pb(Ⅱ), and it was almost unchanged when adding the Fe(Ⅱ), Cr(Ⅲ), Cd(Ⅱ), Co(Ⅱ), Ni(Ⅱ) and Mn(Ⅱ) ions.     

Finally Stable and Homoleptic: Isolation and Characterization of {Cu[Fe(CO)5]2}+ Stabilized with Perfluoroalkoxyaluminate Anion, [Al(OC(CF3)3)4]−

Developments in the chemistry of weakly coordinating anions enabled isolation of numerous unique metal complexes with unusual ligands. An important example is the family of metal-Fe(CO)₅ complexes. In the current paper we present synthesis and thorough characterization of the first truly homoleptic {Cu[Fe(CO)₅]₂}⁺ cation obtained as a salt of weakly coordinating [Al(OR^F)₄]⁻ (R^F=C(CF₃)₃) anion. TGA/DSC/MS study show that its decomposition becomes noticeable only above 110 °C, thus it can be stored as powder in air-free conditions for months. The crystal structure of {Cu[Fe(CO)₅]₂}⁺ shows strong asymmetry of the cation and very short Cu-CO bonds in comparison to analogous {M[Fe(CO)₅]₂}⁺ where M=Ag or Au. Characterization is complemented with analysis of vibrational spectra and extensive DFT calculations which give insight into the energetics of Cu⁺-Fe(CO)₅ systems. Our results show that {Cu[Fe(CO)₅]₂}⁺ is homoleptic only as salt of [Al(OR^F)₄]⁻. Furthermore, in the presence of additional, even weakly basic ligands, the Cu⁺-Fe(CO)₅ bond strength decreases what may contribute to the complex's instability in liquid SO₂ or in the presence of [SbF₆]⁻. These conclusions point at the key role of selection of proper anion and solvent in stabilization of these types of complexes.     

Microwave Promoted Oxidative Addition Reactions of Os3(CO)12: Efficient Syntheses of Triosmium Clusters of the Type Os3(μ-X)2(CO)10 and Os3(μ-H)(μ-OR)(CO)10

Microwave heating allows for the high-yield, one-step synthesis of the known triosmium complexes Os₃(μ-Br)₂(CO)₁₀ (1), Os₃(μ-I)₂(CO)₁₀ (2), and Os₃(μ-H)(μ-OR)(CO)₁₀ with R = methyl (3), ethyl (4), isopropyl (5), n-butyl (6), and phenyl (7). In addition, the new clusters Os₃(μ-H)(μ-OR)(CO)₁₀ with R = n-propyl (8), sec-butyl (9), isobutyl (10), and tert-butyl (11) are synthesized in a microwave reactor. The preparation of these complexes is easily accomplished without the need to first prepare an activated derivative of Os₃(CO)₁₂, and without the need to exclude air from the reaction vessel. The syntheses of complexes 1 and 2 are carried out in less than 15 min by heating stoichiometric mixtures of Os₃(CO)₁₂ and the appropriate halogen in cyclohexane. Clusters 3–6 and 8–10 are prepared by the microwave irradiation of Os₃(CO)₁₂ in neat alcohols, while clusters 7 and 11 are prepared from mixtures of Os₃(CO)₁₂, alcohol and 1,2-dichlorobenzene. Structural characterization of clusters 2, 4, and 5 was carried out by X-ray crystallographic analysis. High resolution X-ray crystal structures of two other oxidative addition products, Os₃(CO)₁₂I₂ (12) and Os₃(μ-H)(μ-O₂CC₆H₅)(CO)₁₀ (13), are also presented.     

Synthesis and X-ray crystal structure of the electron-deficient metal carbonyl cluster [Os3(CO)5(μ3-H)(μ-H)(μ-PtBu2)2(μ-Ph2PCH2PPh2)]

The reaction of [Os₃(CO)₁₀(μ-dppm)] (1) with ^tBu₂PH in refluxing diglyme results in the electron-deficient metal cluster complex [Os₃(CO)₅(μ₃-H)(μ-P^tBu₂)₂(μ-dppm)] (2) (dppm = Ph₂PCH₂PPh₂) in good yields. The molecular structure of 2 has been established by a single crystal X-ray structure analysis. In contrast to the known homologue [Ru₃(μ-CO)(CO)₄(μ₃-H)(μ-H)(μ-P^tBu₂)₂(μ-dppm)] (3), no bridging carbonyl ligand was found in 2. The electronically unsaturated cluster 2 does not react with carbon monoxide under elevated pressure, therefore 2 seems to be coordinatively saturated by reason of the high steric demands of the phosphido ligands.     

Synthesis and structure of Os3(μ-H)3(CO)9(μ3-Sn)Os3(μ-H)(CO)10(PEt2Ph): The first osmium cluster containing a face-capping tin atom

Pyrolysis a the cluster Os₃(µ-H h (CO)₁₀ (SnMe2 H) produced an as yet unidentified purple duster, which upon reaction with PEt₂Ph at room temperature, gave essentially a quantitative yield of the cluster Os₃(µ-H)₃(CO)₉(µ₃-Sn) Os₃(µ-H)(CO)₁₀(PEt₂Ph), 4. The X-ray structure of 4 (as the toluene solvate) shows that it consists Or two Os, triangles linked through a µ₄-Sn unit, such that one of the Os₃ triangle is µ₃-bonded to the Sn atom (Os-Sn range 2.689(2)–2.707(2) Å) and the other is bonded via a single covalent bond (Os-Sn = 2.643(2) Å). The phosphine ligand occupies the equatorial site on a second osmium atom a be latter Os₃ moiety that is syn to the Sn atom; the unique bridging hydride ligarid is believed to occupy a site that Acis to both the P and Sn atoms. Crystallographic data for compound4. 0.5C₇H₈: space group,P ; ca= 11862(4) Å,b = 12.940(4) Å,c = 16.513(5) Å, =68.96(3),=80.60(3)°,=62.49(2).R=0.029, 4118 observed reflections.     

Synthesis and Characterization of a Two-dimensional Cadmium(Ⅱ) Metal Organic Framework with Fes Topology

A new Cd(Ⅱ) coordination polymer, {[Cd(Hnbta)(L)]·H2O}n(L = 1,4-bis(5,6-dimethylbenzimidazol-1-yl)butane), H3nbta= 5-nitrobenzene-1,2,3-tricarboxylic acid), has been hydro-thermally synthesized and characterized by elemental analyses, IR, XRPD, and single-crystal X-ray diffraction. The title compound crystallizes in the monoclinic system, space group P21/n with a = 17.3056(13), b = 11.0114(9), c = 17.7484(14) A, β = 117.3640(10)o, V = 3003.7(4) A3, Z = 4, C31H31CdN5O9, Mr = 730.01, Dc = 1.614 g/cm3, μ = 0.792 mm-1 and F(000) = 1488. The cadmium(Ⅱ) ions are bridged by Hnbta2- to generate a two-dimensional metal organic framework with fes topology. In addition, the thermal stability and fluorescence properties of the complex were also studied.     

Study on the Synthesis and Characterization of Novel Immobilized β-Cyclodextrin Polymer (Ⅰ)

A series of novel β-cyclodextrin polymers was synthesized by immobilization of β-cyclodextrin on the chloromethylated crosslinked polystyrene carriers. The synthetic conditions such as reaction time, temperature, molar feeding ratio of reactants, the degree of crosslinking of polystyrene and the catalysts used were studied in detail and the chemical and physical structures of the formed β-CDpolymers were characterized. Results show that the preparation method is simple and the amount of β-CD immobilized is high. As biomedical adsorbents, they were tested for removal of various endogenous and exogenous toxins such as phenols, aromatic amins, barbitals and unconjugated bilirubin. Results indicate that the adsorptión capacity for those toxins can be enhanced by the inclusion interaction among the β-CD, the substrate molecules and the β-CD polymers.     

Synthesis of Platinum-Triruthenium Clusters Using the Zero-Valent Platinum Reagent Pt(nb)3: X-Ray Crystal Structures of Ru3Pt(CO)11(P-iPr3)2, Ru3Pt(μ-H)(μ3-η3-MeCCHCMe)(CO)9(P-iPr3), Ru3Pt(μ3-η2-PhCCPh)(CO)10(P-iPr3), Ru3Pt(μ-H)(μ4-N)(CO)10(P-iPr3) and Ru3Pt(μ-H)(μ4-η2-NO)(CO)10(P-iPr3)

The complexes Pt(nb)_3-n(P-iPr₃)_n (n=1, 2, nb=bicyclo[2.2.1]hept-2-ene), prepared in situ from Pt(nb)₃, are useful reagents for addition of Pt(P-iPr₃)_n fragments to saturated triruthenium clusters. The complexes Ru₃Pt(CO)₁₁(P-iPr₃)₂ (1), Ru₃Pt(-H)(₃-³-MeCCHCMe)(CO)₉(P-iPr₃) (2), Ru₃Pt(₃-²-PhCCPh)(CO)₁₀(P-iPr₃) (3), Ru₃Pt(-H)(₄-N)(CO)₁₀(P-iPr₃) (4) and Ru₃Pt(-H)(₄-²-NO)(CO)₁₀(P-iPr₃) (5) have been prepared in this fashion. All complexes have been characterized spectroscopically and by single crystal X-ray determinations. Clusters 1–3 all have 60 cluster valence electrons (CVE) but exhibit differing metal skeletal geometries. Cluster 1 exhibits a planar-rhomboidal metal skeleton with 5 metal–metal bonds and with minor disorder in the metal atoms. Cluster 2 has a distorted tetrahedral metal arrangement, while cluster 3 has a butterfly framework (butterfly angle=118.93(2)°). Clusters 4 and 5 posseses 62 CVE and spiked triangular metal frameworks. Cluster 4 contains a ₄-nitrido ligand, while cluster 5 has a highly unusual ₄-²-nitrosyl ligand with a very long nitrosyl N–O distance of 1.366(5) Å.     

Synthesis of the gold-dirhenium ferrocenylacetylide cluster. The crystal structure of Re2(μ-C≡CFc){Au(PPh3)}(CO)8

The thermal reaction of Re₂(CO)₈(NCMe)₂ with Au(CCFc)PPh₃ afforded the cluster Re₂(-CCFc){Au(PPh₃)}(CO)₈, which was characterized by X-ray diffraction analysis.     

Ligand substitution reaction of (μ-H)Os3(CO)10(μ-COMe) with 1,1'-bis(diphenylphosphino) ferrocene

Reaction of (μ-H)Os₃(CO)₁₀(μ-COMe) with 1,1'-bis(diphenylphosphino)-ferrocene (dppf) produces (μ-H)Os₃(CO)₈(μ-COMe){μ-η²-(η⁵-C₅H₄PPh₂)₂Fe} (1) and (μ-H)₂Os₃(CO)₇(μ-COMe){μ-η³-(η⁵-C₅H₃PPh₂)Fe(η⁵-C₅H₄PPh₂)} (2). Thermolysis of 1 leads quantitatively to 2. These compounds have been characterized by ¹H, ³¹P, and ¹³C NMR, IR, and mass spectroscopies. Compound 2 crystallizes in space group P 2₁/c with a = 11.898(2), b = 21.266(3), c = 18.262(3) Å, β = 104.71(1)°, V = 4469(1) ų, Z = 4, and R_F = 0.029.