Oxo-bridged Complex Research Articles

Nuclease Activity of Oxo-bridged Diiron Complexes

The dinuclear oxo-bridged complexes [Fe(salen)]2O, [Fe(salen)]2O·X (where X=pyridine, perchlorate) cleave plasmid pBR322 DNA in concert with H2O2.

A Preorganized Siderophore: Thermodynamic and Structural Characterization of Alcaligin and Bisucaberin, Microbial Macrocyclic Dihydroxamate Chelating Agents(1).

The iron coordination chemistry of two macrocyclic dihydroxamate siderophores, alcaligin (AG) and bisucaberin (BR), has been investigated thermodynamically and structurally. Alcaligin is a siderophore of freshwater bacteria as well as mammalian pathogens, including the bacterium that causes whooping cough in humans, while bisucaberin, a structural analogue of alcaligin, is produced by marine bacteria. Both alcaligin and bisucaberin form 1:1 ferric complexes (FeL(+)) in acidic conditions and 2:3 ferric complexes (Fe(2)L(3)) at and above neutral pH. The stability constants of these macrocyclic dihydroxamate siderophores differ significantly from that of rhodotorulic acid (RA), a linear dihydroxamate siderophore. Notably, K(FeL) of alcaligin is 32 times greater than that of rhodotorulic acid, while the subsequent stepwise formation constant for Fe(2)L(3) is 3 times less. The Fe(III) complexes of alcaligin are stereospecific; the absolute configuration of the Fe(2)L(3) complex (circular dichroism and X-ray structure) is Lambda. The structure of the Fe(2)L(3) alcaligin complex is a topological alternative to the triple-helicate structure of the rhodotorulic complex Fe(2)(RA)(3). The structures of the free ligand and the bisbidentate ligand in the FeL complex are essentially identical, indicating that alcaligin is highly preorganized for metal ion binding. This explains the difference in K(FeL) between alcaligin and rhodotorulic acid, as well as explaining the monobridged topology of the Fe(2)L(3) alcaligin complex. The protonation constants (log K(a1) and log K(a2)) are 9.42(5) and 8.61(1) for alcaligin and 9.49(2) and 8.76(3) for bisucaberin. The stepwise formation constants of the Fe(III) complexes (log K(ML) and log K(M)()2(L)()3) are 23.5(2) and 17.7(2) for alcaligin and 23.5(5) and 17.2(5) for bisucaberin. The overall formation constants (log beta(230)) of alcaligin and bisucaberin are 64.7(1) and 64.3(1). The solution chemistry of Fe(III) and alcaligin was further investigated at a lower ligand to metal ratio (1:1). At high pH, a novel 2:2 ferric bis-&mgr;-oxo-bridged complex of alcalagin forms (Fe(2)L(2)O(2)(2)(-)) with a log beta(22)(-)(4) of 16.7(2). This species exhibits behavior consistent with an iron bis-&mgr;-oxo complex, including antiferromagnetic coupling. Crystal data: Fe(2)(AG)(3).25H(2)O crystallizes in the orthorhombic space group P2(1)2(1)2(1) with a =13.3374(4) Å, b = 16.1879(5) Å, c = 37.886(1) Å, V = 8179.7(4), Z = 4. For 5512 reflections with F(o)(2) > 3sigma(F(o)(2)) the final R (R(w)) = 0.053(0.068).

Synthesis and characterization of a new unsymmetrical μ-oxo-bridged iron(III) complex with triphenylarsine oxide ligands

A new unsymmetrical oxo-bridged complex [Fe 2O(OAsPh 3) 4Cl 3][FeCl 4]·CH 3CN was synthesized and characterized by X-ray structural analysis, elemental analysis, spectral and magnetic data. The compound crystallizes in a monoclinic system, space group P2 1/ c, with a = 13.77(1), b = 21.50(2), c = 25.62(2) A ̊ , β = 90.22(7)°, and Z = 4 (R = 0.0335 for 5859 independent reflections with I > 3 σ( I)). Crystal structure analysis revealed that one iron atom is pentacoordinated by four triphenylarsine oxide ligands and a μ-oxo ligand which connects a tetracoordinated iron atom with teh chromophore FeCl 3O. The magnetic properties of the complex were investigated in the 4.2–300 K temperature range and these data correspond to the electron paramagnetic resonance spectra.

Zirconocenes as Initiators for Carbocationic Isobutene Homo- and Copolymerizations

The zirconocene complexes Cp2ZrMe2 and Cp*2ZrMe2 activated with B(C6F5)3 initiate the carbocationic polymerization of isobutene and isobutene−isoprene copolymerizations to IIR rubbers at temperatures as high as −30 °C. Unlike conventional metal halide initiators, these metallocene-based initiator systems produce both homo- and copolymers of broadly similar molecular weights. Copolymers prepared in the presence of ca. 2 mol % isoprene show a diene incorporation rate of 1.4−1.7%, with the typical 1,4-trans structure. Comparison of the effectiveness of zirconocene dialkyls with that of the metallocene hydrolysis products Cp*2Zr(OH)2 and (Cp2ZrMe)2(μ-O) in the presence of B(C6F5)3 suggests that initiation by traces of protons is less efficient than initiation by cationic metallocene alkyl species, while oxo-bridged complexes (Cp‘2ZrMe)2(μ-O)/B(C6F5)3 (Cp‘ = C5H5 or C5H4SiMe3) are inactive.

Reactions of smectites with binuclear oxobridged iron complexes of N-alkyl-N,N-bis (2-pyridylmethyl)amines

AbstractCationic binuclear oxo- and carboxylate bridged Fe(III) complexes of N-alkyl-N,Nbis(2-pyridylmethyl)amines are introduced into the interlayer region of smectites by cation exchange reactions. The reaction can be divided into three steps. After a predominant loading of external surfaces, cation exchange sites at internal surfaces react, accompanied by considerable stmctaral expansion. Both reaction stages belong to the steep section of the exchange isotherms. At a certain loading, which depends on the complex substituents and the layer charge of the smectite, the isotherms become flat. With bulky shaped complex cations and highly charged smectites, exchange is not quantitative; vermiculite-type minerals show a very small complex uptake. For this behaviour, both thermodynamic and kinetic reasons must be considered. From these results the number of cation exchange positions at external surfaces of smectite crystals may be estimated.

The first gold(III) dinuclear cyclometallated derivatives with a single oxo bridge

The reaction of the gold(III) cyclometallated complexes [Au(L)Cl][BF4] [L = N2C10H7(CHMeC6H4)-6 1 or N2C10H7(CMe2C6H4)-6 2, where N2C10H8 = 2,2′-bipy] with AgBF4 in acetone solution affords the acetonyl derivatives [Au(L){CH2C(O)Me}][BF4], 3 and 4, and the dinuclear oxo-bridged complexes [Au2(L)2(µ-O)][BF4]2, 5 and 6; the crystal structure of complex 6 gives evidence for an unprecedented unsupported Au–O–Au bridge.

Mixed-valent μ-oxo-bridged diiron complexes produced by radiolytic reduction at 77 K studied by EPR

Several dinuclear diferric complexes were prepared, bridged by only an oxo ion, by an oxo ion and additionally one or two carboxylate groups, or by two hydroxo ions. Frozen solutions of these EPR-silent diferric complexes were radiolytically reduced by γ-irradiation at 77 K. The reduced forms gave EPR spectra typical of mixed-valent diiron species with S = 1/2. The yield was about 50% at high doses. With 57Fe replacing 56Fe the spectral features were broadened because of hyperfine interaction with one or both of the 57Fe nuclei. All oxo-bridged complexes give mixed-valent species with unbroadened EPR spectra observable up to 110 K. The anisotropy is small, Δg = g 1–g 3<0.07, and g av = (g 1+g 2+g 3)/3 falls in the range 1.93–1.96. Annealing at T≥115 K causes the EPR spectra to change and finally become more anisotropic, 0.14<Δg<0.32 and to have smaller g av, 1.78<g av<1.89. These spectra are observable only at T≤35 K. Radiolytic reduction of the diferric complexes with hydroxo bridges leads directly without annealing to this second type of mixed-valent species. The annealing-induced transition from a primary to a secondary mixed-valent species in the case of an oxo-bridged diferric starting complex is suggested to be a structural relaxation including protonation of the bridge. Annealing at temperatures above ca. 180 K and final thawing causes the mixed-valent dinuclear species to disappear, probably by disintegration to mononuclear species. These mixed-valent species are useful models for similar species in proteins, where primary-type species may take part in transient electron transfer, and the secondary-type species are usually more persistent forms in redox reactions. For proteins, available data show that there is a tendency for both primary and secondary species to have larger g anisotropy, Δg, and smaller g av, than obtained with the models. These differences suggest that the diiron centers of proteins are affected by their specific surroundings. Our results also show that the nature of the bridge, oxo or hydroxo, may not always safely be determined from a measured J value. Measurement of the EPR parameters, Δg, g av and limiting temperature of observation (relaxation properties) of a mixed-valent complex, or, in the case of a diferric complex, of the primary mixed-valent species induced by radiolysis at 77 K, offers an alternative empirically based method to determine the nature of the bridge.

Solvate Molecule Effects and Unusual (57)Fe Mössbauer Line Broadening in the Valence Detrapping of Mixed-Valence [Fe(3)O(O(2)CCH(3))(6)(3-Et-py)(3)].S.

A new series of mixed-valence &mgr;(3)-oxo-bridged Fe(3)O complexes with the composition [Fe(3)O(O(2)CCH(3))(6)(3-Et-py)(3)].S, where 3-Et-py is 3-ethylpyridine and the solvate molecule S is either 0.5C(6)H(5)CH(3) (1), 0.5C(6)H(6) (2), CH(3)CN (3), or CH(3)CCl(3) (4), is reported. The complex [Fe(3)O(O(2)CCH(3))(6)(3-Et-py)(3)].0.5C(6)H(5)CH(3) (1) crystallizes in the orthorhombic space group Fdd2 which at 298 K has a unit cell with a = 22.726(8) Å, b = 35.643(14) Å, c = 20.816(6) Å, and Z = 16. Refinement with 5720 observed [F > 5sigma(F(o))] reflections gave R = 0.0337 and R(w) = 0.0390. An analysis of the bond lengths in complex 1 shows that it is the most valence-trapped Fe(3)O complex reported at room temperature. The complex [Fe(3)O(O(2)CCH(3))(6)(3-Et-py)(3)].CH(3)CCl(3) (4) crystallizes in the triclinic space group P&onemacr; which at 238 K has a unit cell with a = 12.764(2) Å, b = 13.1472(2) Å, c = 15.896(3) Å, alpha = 78.01(2) degrees, beta = 89.38(2) degrees, gamma = 61.38(1) degrees, and Z = 2. Refinement with 6264 observed [F > 5sigma(F(o))] reflections gave R = 0.0435 and R(w) = 0.0583. In this &mgr;(3)-oxo-bridged complex all three iron ions are inequivalent. Powder X-ray diffraction patterns taken at room temperature show that complexes 1 and 2 are isostructural and that complexes 3 and 4 are isostructural. Variable-temperature (57)Fe Mössbauer spectra were collected for all four complexes. The data for complexes 1 and 2 clearly indicate that these two complexes are totally valence trapped. On the other hand, Mössbauer spectra (43-293 K) for complexes 3 and 4 show that these two complexes become valence detrapped at temperatures near room temperature. Two doublets are seen at low temperature and they move together to become a single doublet at approximately 293 K. Examination of the line width versus temperature for each of the two components of the two doublets points to a curiosity. The two components of the "Fe(III)" doublet and the lower-velocity component of the "Fe(II)" doublet do not exhibit any line broadening, whereas the higher velocity "Fe(II)" component shows a surge in line width in the approximately 70-150 K range. Possible explanations for these unusual line width responses are discussed.

(μ-Oxo)diiron Complexes of Gated Glyoximes. Structural Changes Accompanying Ligation Trans to the Oxo Bridge

Structures of new low-spin oxo-bridged complexes of bis[(diphenylboryl)dimethylglyoximato]iron, Fe((DMG)BPh2)2, are reported. The pentacoordinate complex, 1 = [Fe((DMG)BPh2)2]2O, contains a bent Fe−O−Fe bridge (166.0°) with the irons each displaced 0.3 Å out of the N4 planes toward the oxo ligand. The Fe−μ-O bond length (1.7097(10) Å) is the shortest yet reported. Both axial phenyl groups are directed to the trans face, creating a superstructure which is collapsed around the vacant binding site. In the butylamine derivative, 2 = [(BuNH2)Fe((DMG)BPh2)2)]2O, the Fe−O−Fe bridge is linear (178.6°) with iron in the N4 plane and Fe−O bond lengths of 1.766(6) Å. The BuNH2 ligand is sandwiched between the axial phenyl groups in intimate contact with them. Structural changes accompanying ligation and their consequences are compared with those in heme systems. Crystal data for 1: orthorhombic, Pnna, a = 17.440(3) Å, b = 21.381(4) Å, c = 16.896(3) Å, V = 6300(2) Å3, Z = 4, R = 0.068. Crystal data for 2 (CHCl3 disolvate): triclinic, P1̄, a = 13.445(3) Å, b = 14.525(4) Å, c = 23.877(6) Å, α = 96.01°, β = 92.61°, γ = 117.40(1)°, V = 4094(2) Å3, Z = 2, R = 0.086.

Effect of substituents in the ligand on oxidation of alkanes catalyzed by binuclear oxo-bridged iron complexes

Oxidation of alkanes (methane, ethane, hexane, and cyclohexane) by hydrogen peroxide andtert-butyl hydroperoxide in acetonitrile catalyzed by binuclear μ-oxo-bridged iron complexes [Fe2OL4(H2O)2](ClO4)4 and [Fe2OL2PhCOO)2(H2O)2](ClO4)2, where L = bpy, 4,4′-Me2bpy, 4,4′-(ClCH2)2bpy, phen, and 5-NO2phen, was studied. It was shown that the nature of the substituent in the ligand affects both the rate of the catalyzed peroxide decomposition and catalytic activity of the complexes studied in the alkane oxidation.

Analysis of Multiply Charged Oxo-Bridged Complexes by Electrospray Ionization Mass Spectrometry

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTAnalysis of Multiply Charged Oxo-Bridged Complexes by Electrospray Ionization Mass SpectrometryUlla N. Andersen, Christine J. McKenzie, and Gustav BojesenCite this: Inorg. Chem. 1995, 34, 6, 1435–1439Publication Date (Print):March 1, 1995Publication History Published online1 May 2002Published inissue 1 March 1995https://doi.org/10.1021/ic00110a022RIGHTS & PERMISSIONSArticle Views149Altmetric-Citations46LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (437 KB) Get e-Alerts Get e-Alerts

A quantum chemical ab initio study of the superexchange coupling in binuclear oxygen-bridged Ni(II) complexes

Abstract Quantum chemical ab initio calculations have been performed for binuclear Ni(II) complexes of the form L 5 NiONiL 5 and L 4 NiO 2 NiL 4 , with either one linear oxygen bridge or with two equivalent oxygen bridges and NiONi angles between 80° and 110°. He-like model ligands L have been used instead of the macrocyclic ligands which are necessary in the experiments to stabilize the complexes. The spin coupling between the two Ni(II) ions is antiferromagnetic in the linear oxo-bridged complex, with an exchange integral J of about −30 cm −1 at the CASSCF level and about −80 cm −1 at the multi-reference CEPA level. In the bioxygen-bridged complex the coupling is antiferromagnetic for NiONi angles smaller than 85° and larger than 102° and weakly ferromagnetic in between with J ≈ 10 cm −1 . Comparison with experiment and an interpretation of the exchange coupling by means of perturbation theory in terms of covalent and ionic molecular orbital configurations is also given.

Coordination and oxidation of vanadium(II) by 1,2-bis(2-sulfidophenylsulfanyl)ethane(2–)(S4): the structures of [V(S4)tmeda], the first example of vanadium(II)–sulfide coordination, and of [V3(µ-O)2(S2)4(tmeda)2](S2= 1,2-benzenedithiolate(2–)

[VCl2(tmeda)](tmeda =N,N,N′,N′-tetramethylethylenediamine) reacts with the tetradentate sulfur ligand 1,2-bis(2-sulfidophenylsulfanyl)ethane(2–)(S4) to form [V(S4)tmeda] with S4 acting as a thiolato and sulfide donor; the trinuclear, linear, oxo-bridged complex [V3(µ-O)2(S2)4(tmeda)2][S2= 1,2-benzenedithiolate(2–)] is formed as a byproduct.

X-ray Structure and Physical Properties of the Oxo-Bridged Complex [(F8-TPP)Fe-O-Cu(TMPA)]+, F8-TPP = Tetrakis(2,6-difluorophenyl)porphyrinate(2-), TMPA = Tris(2-pyridylmethyl)amine: Modeling the Cytochrome c Oxidase Fe-Cu Heterodinuclear Active Site

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTX-ray Structure and Physical Properties of the Oxo-Bridged Complex [(F8-TPP)Fe-O-Cu(TMPA)]+, F8-TPP = Tetrakis(2,6-difluorophenyl)porphyrinate(2-), TMPA = Tris(2-pyridylmethyl)amine: Modeling the Cytochrome c Oxidase Fe-Cu Heterodinuclear Active SiteKenneth D. Karlin, Alaganandan Nanthakumar, Stephen Fox, Narasimha N. Murthy, Natarajan Ravi, Boi Hanh Huynh, Robert D. Orosz, and Edmund P. DayCite this: J. Am. Chem. Soc. 1994, 116, 11, 4753–4763Publication Date (Print):June 1, 1994Publication History Published online1 May 2002Published inissue 1 June 1994https://doi.org/10.1021/ja00090a023RIGHTS & PERMISSIONSArticle Views754Altmetric-Citations84LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (3 MB) Get e-AlertsSupporting Info (3)»Supporting Information Supporting Information Get e-Alerts

Alkylierung kontra Protolyse: Alternative Synthesewege der Reaktion von μ-Hydroxy-cyclooctadien(1,5)-rhodium(I) Dimer mit Methylderivaten des Ti IV. Synthese, Röntgenkristallstrukturanalyse und heterogen-katalytische Testung des neuartigen oxoverbrückten Titan-Rhodium-Komplexes {(μ 3( Rh, Rh, Ti) -O) 4[Rh I(COD-1,5)] 4[Ti IV( tC 4H 9O) 2] 2}

The reaction of [(μ-OH)Rh(COD-1,5)] 2 with CH 3Ti(O tC 4H 9) 3 and Cp 2Ti(CH 3) 2, respectively, is described. Whereas CH 3Ti(O tC 4H 9) 3 gives alkylation of the Rh I complex at low temperatures, the new oxo-bridged complex {(μ 3-O) 4[Rh(COD-1,5)] 4[Ti( tC 4H 9O) 2] 2} ( 1) is formed at room temperature in the course of a protolysis reaction. The data of an X-ray structural investigation as well as the first results of using 1 as a precursor in heterogeneous catalysed hydrogenation reactions are discussed.

Two different terminal nitrate bonding modes in [Fe2O(NO3)4(C7H7N3)4

Treatment of Fe(NO3)3·9H2O with 1-methylbenzotriazole in EtOH–CH(OEt)3 gave the unique, oxo-bridged complex [Fe2O(NO3)4(C7H7N3)4]; crystal structure and Mossbauer studies showed that the molecule has both bidentate and monodentate nitrates and possesses an S= 0 ground state, respectively.

In-situ spectrocyclic voltammetry investigations of the formation of a water oxidation catalyst [(bpy) 2(H 2O)RuORu(H 2O)(bpy) 2] 4+ at a Nafion®-coated electrode

The monomeric ruthenium complex cis-[Ru(bpy) 2(H 2O) 2] 2+ was adsorbed into a Nafion® film coated onto an indium tin oxide (ITO) electrode. In-situ spectrocyclic voltammetric investigations under different pH conditions showed that the monomeric complex in the Nafion film dimerizes upon oxidation, with obvious spectral changes, to yield the corresponding oxo-bridged complex [(bpy) 2(H 2O)RuORu(H 2O)(bpy) 2] 4+ which is a water oxidation catalyst. The reversible formation of the dimer and monomer during oxidation and reduction of the corresponding complexes at appropriate potentials was established by in-situ spectrocyclic voltammetry at a Nafion-film-coated ITO electrode.

Übergangsmetallkomplexe mit Schwefelliganden, LXI / Transition Metal Complexes with Sulfur Ligands, LXI

In order to study the properties of sulfur coordinated metal centres, the chromium and tungsten complexes [Cr(NO)(µ-′S4′)]2 (4), (NR4)2[W(NO)2(′S2′)2] (1) (R = Me (la), n-Bu (lb)), [W(NO)2(′S4′)] (2), [µ-O{W(NO)(′S4′)}2] (3) and [W(NPR3)(NO)(′S4′)] (5) (R = Me (5a), Et (5 b)) were synthesized (′S2 ′2- = 1.2-benzenedithiolate(2-); ′S4 ′2- = 1.2-bis(2-mercaptophenylthio)ethane(2-)). la and lb result from the reductive nitrosylation of Li2[W(′S2′)3] which was prepared by reduction of [W(′S2′)3] with n-BuLi. la was also obtained from [W(NO)2(Cl)2]n, ′S2 ′2- and NMe4 +. Alkylation of la or lb by 1.2-dibromoethane yields 2, whose X-ray structure analysis shows that W is pseudooctahedrally coordinated by two trans thiolato S, two cis thioether S and two cis N atoms of linear W-NO groups. 2 was also obtained from [W(NO)2(CH3CN)4](BF4)2 or [W(NO)2(Cl)2]n and ′S4 ′2--. The reaction of [W(NO)2(Cl)2]n yielded the dinuclear oxo-bridged complex 3 as a by-product in small amounts. In preparative amounts, 3 was synthesized by hydrolysis of [W(Cl)(NO)(′S4′)]. In contrast to the analogous Mo complex, 2 does not react with N2H4; with the ligands PMe3 and PEt3, it gives the corresponding phosphiniminato complexes 5 and free phosphineoxides OPR3. In order to compare the [M(NO)2(′S4′)] complexes (M = Cr, Mo, W), the structure of [Cr(NO)2(′S4′)] was determined by X-ray structure analysis. The Cr complex exhibits the same molecular coordination geometry as 2. While growing crystals of [Cr(NO)2(′S4′)], the dinuclear Cr complex 4 was also formed. Its X-ray structure analysis shows each of the Cr centres to be coordinated pseudooctahedrally by five sulfur donors and one nitrosyl N donor. 4 was also obtained by the reaction of [Cr(CO)4(nor)] with ′S4 ′2- and NOBF4.

Alkenyl- und Ethylkomplexe des Titanocens. Molekülstruktur von [Cp 2Ti(CMeCHMe)] 2μ-O

The acetylene complexes Cp 2Ti(PMe 3)(C 2H 2) ( 1) and Cp 2Ti(C 2Me 2) ( 2) and the ethylene complex Cp 2Ti(C 2H 4) ( 3) react with alcohols ROH (R = Me, Et, Ph) to give the η 1-alkenyl complexes Cp 2Ti(CR′=CHR′)(OR) (R′ = H, Me) and the ethyl complexes Cp 2Ti(Et)(OR). The reaction of 1–3 with water results in the formation of the oxo-bridged dimeric complexes [Cp 2Ti(CR′=CHR′)] 2μ-O and [Cp 2Ti(Et)] 2μ-O. The acids HX (X = Cl, CF 3COO) react with 1 and 2 to give the monomeric η 1-alkenyl compounds Cp 2Ti(CR′=CHR′)(X). The trifluoroacetate derivatives are very unstable and react with water to yield the stable oxo-bridged complex [Cp 2Ti(OOCCF 3)] 2μ-O. The crystal structure of [Cp 2Ti(CMe=CHMe)] 2μ-O is described.

Ethylkomplexe des zirkonocens

The ethylene complex Cp 2Zr(C 2H 4)(PMe 3) ( 1) reacts readily with a variety of substrates: alcohols ROH (R  Me, Et, Ph) give the alkoxy ethyl complexes Cp 2Zr(Et)(OR), the mercaptan tBuSH gives the thiolate ethyl complex Cp 2Zr(Et)(S tBu), water gives the dinuclear oxo-bridged complex [Cp 2Zr(Et)] 2μ-O, and the acids HX (X  Cl, H(O)CO, and the CH 3(O)CO, CF 3(O)CO) give the complexes Cp 2Zr(Et)X and Cp 2ZrX 2. The reaction of Cp 2Zr(Et)[OC(O)H] with water gives the dinuclear Cp 2Zr[OC(O)H] 2μ-O. Cp 2Zr(Et)(S tBu) reacts with HX (X  H(O)CO, CH 3(O)CO) and ROH to yield the carboxylate ethyl complexes Cp 2Zr(Et)X and the alkoxy ethyl complexes Cp 2Zr(Et)(OR).