Synthesis and X-ray crystal structures of [Ph2PMe2][(η-C5H4Bu)2Li] and [(η-C5H4Bu)2Yb(Cl)CH2P(Me)Ph2]

The interaction of [(η⁵-C₅H₄Bu^t)₂YbCl · LiCl] with one equivalent of Li[(CH₂) (CH₂)PPh₂] in tetrahydrofuran gave [Ph₂PMe₂][(η⁵-C₅H₄Bu^t)₂Li] (1) and [(η⁵-C₅H₄Bu^t)₂Yb(Cl)CH₂P(Me)Ph₂] (2) in 10% and 30% yields, respectively. 1 could also be prepared in 70% yield from the reaction of [Ph₂PMe₂][CF₃SO₃] with two equivalents of (C₅H₄Bu^t)Li. Both compounds have been fully characterized by analytical, spectroscopic and X-ray diffraction methods. The solid state structure of 1 reveals a sandwich structure for the [(η⁵-C₅H₄Bu^t)₂Li]⁻ anion.     

Synthesis and structure of ansa-cyclopentadienyl pyrrolyl titanium complexes: [(η-C5H4)CH2(2-C4H3N)]Ti(NMe2)2 and [1,3-{CH2(2-C4H3N)}2(η-C5H3)]Ti(NMe2)

Reaction of ansa-cyclopentadienyl pyrrolyl ligand (C₅H₅)CH₂(2-C₄H₃NH) (2) with Ti(NMe₂)₄ affords bis(dimethylamido)titanium complex [(η⁵-C₅H₄)CH₂(2-C₄H₃N)]Ti(NMe₂)₂ (3) via amine elimination. A cyclopentadiene ligand with two pendant pyrrolyl arms, a mixture of 1,3- and 1,4-{CH₂(2-C₄H₃NH)}₂C₅H₄ (4), undergoes an analogous reaction with Ti(NMe₂)₄ to give [1,3-{CH₂(2-C₄H₃N)}₂(η⁵-C₅H₃)]Ti(NMe₂) (5). Molecular structures of 3 and 5 have been determined by single crystal X-ray diffraction studies.     

Cyclopentadienyl-ruthenium and -osmium chemistry : XXXIX. Syntheses of novel alkynyl-ruthenium complexes. X-Ray structures of two forms of {Ru(PPh3)2(η-C5H5)}2(μ-C4) and of Ru{CCC(O)Me}(PPh3)2(η-C5H5)

Reactions between [Ru(thf)(PPh₃)₂(η-C₅H₅)]⁺ and lithium acetylides have given further examples of substituted ethynylruthenium complexes that are useful precursors of allenylidene and cumulenylidene derivatives. From Li₂C₄, mono- and bi-nuclear ruthenium complexes were obtained: single-crystal X-ray studies have characterised two rotamers of {Ru(PPh₃)₂(η-C₅H₅)}₂(μ-C₄), which differ in the relative cis and trans orientations of the RuL_n groups. Protonation of Ru(CCCCH)(PPh₃)₂(η-C₅H₅) afforded the butatrienylidene cation [Ru(C=C=C=CH₂)(PPh₃)₂(η-C₅H₅)]⁺, which reacted readily with atmospheric moisture to give the acetylethynyl complex Ru{CCC(O)Me}(PPh₃)₂(η-C₅H₅), also fully characterised by an X-ray structural study.     

Synthesis and Anti-inflammatory Action of （η-C5H5 ）2Ti（ Sal）2 and （η-C5H5 ）2Ti（Clo）2

IntroductionSince K pf[1]discovered that dicyclopenta die-nyltitanium dichloride possesses antitumour action in1979,a large number of cyclopentadienyltitanium com-plexes with different substituents have been synthe-sized[2,3].The experimental data reveal …     

Mechanism of formation of (η-C5H5)2NbH3 from the reaction of (η-C5H5)2NbCl2 with hydridoaluminate reducing agents

The mechanism of the transformation of (η⁵-C₅H₅)₂NbCl₂ to (η⁵-C₅H₅)₂NbH₃ by hydridoaluminate reducing agents has been investigated. Results suggest disproportionation of a niobium(IV) hydrite, leading to the trihydride product and a niobium(III) hydridoaluminate, (η⁵-C₅H₅)₂NbH₂AlR₂, which in turn is converted to the trihydride on hydrolysis. (η⁵-C₅H₅)₂NbH₂AlH₂ has been isolated; deuterium labelling shows that hydrogens exchange between ring and metal-bridging positions in this molecule.     

Electrochemical reduction of the dithiophosphate complexes CpFe(CO)2[η-SP(S)(OR)2], (Cp = η-C5H5 or η-C5Me5)

The reductive electrochemistry of compounds of the type CpFe(CO)₂L (Cp = η-C₅H₅, η-C₅Me₅; L = SP(S)(OEt)₂, SP(S)(OⁱPr)₂) has been examined by polarography, cylic voltammetry and coulometry. The first one-electron reduction step leads to a bond rupture process with formation of a mercury compound, [CpFe(CO)₂]₂Hg, at a mercury electrode and the corresponding dimer species at a platinum electrode. The second reduction step corresponds to the reduction of the dimer [CpFe(CO)₂]₂, except in the polarographic reduction of pentamethylcyclopentadienyl compounds.     

Preparative use of electrode catalyzed substitution reactions; synthesis of Fe(CO)(PPh3)(η-C5H5)COCH3

It is shown that electrode catalysis of substitution reactions can operate even for systems with rather slow chemical steps and, furthermore, for those which are electrochemically irreversible. A procedure is described for synthesis of Fe(CO)(PPh₃)(η⁵-C₅H₅)COCH₃ from Fe(CO)₂(η⁵-C₅H₅)CH₃ and triphenylphosphine. A simplified mechanism for the catalytic chain, is given and discussed in terms of the structure of the reacting species.     

Role of B(C6F5)3 in activating the nickel-methyl complex (η-C5H5)Ni(CH3)(PPh3) to initiate the vinyl polymerization of norbornene

The Ni-methyl complex (η⁵-C₅H₅)Ni(CH₃)(PPh₃) (1) reacted with B(C₆F₅)₃ to give an unstable contact ion-pair complex with a μ-methyl bridge between the Ni and B atoms. Formation of the B-CH₃ bond was confirmed by the reaction of this complex with PPh₃ to give [(η⁵-C₅H₅)Ni(PPh₃)₂][B(CH₃)(C₆F₅)₃] which was structurally characterized. Spontaneous decomposition of the contact ion-pair complex yielded (η⁵-C₅H₅)Ni(C₆F₅)(PPh₃) which is very stable and does not show any reactions with norbornene with or without added B(C₆F₅)₃. ¹⁹F NMR study showed that the polynorbornene obtained by the catalysis of 1/B(C₆F₅)₃ system has the C₆F₅ end-group. A series of reactions, which includes CH₃/C₆F₅ exchange between the Ni and B centers with concomitant dissociation of PPh₃ to accept coordination of a norbornene monomer, is proposed as the route to active species that can initiate vinyl polymerization of norbornene.     

Synthesis and crystal structure of the complex [MoW(OEt)(μ-CH2){μ-C(C6H4Me-4)C(Me)O}(η-C7H7)(η-C2B9H10Me)]

The complex [MoW(μ-CC₆H₄Me-4)(CO)₂(η⁷-C₇H₇)(η⁵-C₂B₉H₁₀Me)] reacts with diazomethane in Et₂O containing EtOH to afford the dimetal compound [MoW(OEt)(μ-CH₂){μ-C(C₆H₄Me-4)C(Me)O}(η⁷-C₇H₇)(η⁵-C₂B₉H₁₀Me)]. The structure of this product was established by X-ray diffraction. The Mo---W bond [2.778(4) Å] is bridged by a CH₂ group [μ-C---Mo 2.14(3), μ-C---W 2.02(3) Å] and by a C(C₆H₄Me-4)C(Me)O fragment [Mo---O 2.11(3), W---O 2.18(2), Mo---C(C₆H₄Me-4) 2.41(3), W---C(C₆H₄Me-4) 2.09(3), Mo---C(Me) 2.26(3) Å]. The molybdenum atom is η⁷-coordinated by the C₇H₇ ring and the tungsten atom is η⁵-coordinated by the open pentagonal face of the nido-icosahedral C₂B₉H₁₀Me cage. The tungsten atom also carries a terminally bound OEt group [W---O 1.88(3) Å]. The ¹H and ¹³C-{¹H} NMR data for the dimetal compound are reported and discussed.     

The crystal and molecular structure of (---)436-(η-C5H5)Fe(CO)(CH3CO)[Ph2PNHCH(Me)(Ph)]

The X-ray crystal structure and absolute configuration of (−)₄₃₆-(η⁵-C₅H₅)Fe(CO)(CH₃CO)[Ph₂PNHCH(Me)(Ph)] have been determined from single crystal diffraction data. The compound crystallizes in the monoclinic space group P2₁ with two molecules in a unit cell of dimensions a = 10.676(4), b = 8.913(7), c = 13.275(9) Å, and β = 91.36°. The structure was solved by the Patterson method and refined to a final R value of 4.7% using 2299 independent data. The iron atom has distorted octahedral coordination, and the configuration at the iron is found to be (S) for the (−)₄₃₆ diastereoisomer. The Fe---Cp distances average 2.131 Å, with an Fe-(ring centroid)distance of 1.76 Å. The Fe-acetyl distance is virtually identical to that found in another iron/acetyl complex, but shows substantial variation from other compounds where the nature of the C(=O)R group is changed. Comparison to the Mo-alkyl/Mo-acetyl series is made, and the argument for back-donation in transition metal acyls is strengthened.

The orientation of the acetyl group is determined by a strong NHO intra-molecular hydrogen bond having an NO separation of only 2.86 ». The phosphine ligand has a very short Fe---P bond which could be in part caused by the role of the adjacent nitrogen in hydrogen bonding. The remaining ligand geometry is the same as that found in a recently reported ruthenium structure, although the absolute configurations at the chiral carbons are reversed, with the current compound being designated (S) at this site.     

First examples of η- and η --- η-coordination in triphosphorus analogues of ferrocene. Crystal structure of the iron sandwich complex [Fe(η-C5H5) (η-C2R2P3)W (CO)5] (R = Bu)

Syntheses of the novel sandwich compounds [Fe(η⁵-C₅H₅)(η⁵-C₂R₂P₃)] and [Fe(η⁵-C₅H₅)(η⁵-C₂R₂P₃)W(CO)₅], (R = Bu^t), are described. The mode of attachment of the [W(CO)₅] fragment in the latter compound has been determined by NMR and single crystal X-ray diffraction studies.     

First structural evidence for complexes containing arsadiphospholyl anions. Crystal structure of the iron(II) complex [Fe(η-C5H5) (η-C2Bu2AsP2)W(CO)5]

The preparation of novel 1-arsa-3,4-diphospholyl and 3-arsa-1,4-diphospholyl anions of the type (C₂^tBu₂AsP₂)⁻ is described. Spectroscopic and structural characterisation of mono-and bi-metallic complexes of these anions are also reported.     

Photochemical reactions of the isostructural 17- and 18-electron complexes (η-C5H5)M(Me)PPh3 (M=Co, Ni)

The photochemical reactions of the title complexes were studied in air-free benzene solution. In both cases photolysis leads to the production of complexes of the formula (η⁵-C₅H₅)M(PPh₃)₂. Both reactions are the result of the initial loss of a methyl radical from the excited state. The primary photoproduct, (η⁵-C₅H₅)MPPh₃ (M=CO, Ni), then scavenges neutral ligands from the solution to yield, in the case of PPh₃, (η⁵-C₅H₅)M(PPh₃)₂. In the absence of uncoordinated ligand in the reaction solution, the cobalt derivative reacts with the starting material to yield (η⁵-C₅H₅)Co(PPh₃)₂, a methyl radical and (η⁵-C₅H₅)Co(solvent)_n.     

Synthesis and reactivity of new heterodinuclear iron/rhenium Cx complexes of the formula (η-C5Me5)Re(NO)(PPh3)(CC)n(η-dppe)Fe(η-C5Me5) (n = 3, 4): Redox properties and a dicobalt hexacarbonyl adduct

We report in this communication the synthesis and characterization of two Fe/Re heterodinuclear complexes 3_n of formula (η⁵-C₅Me₅)Re(NO)(PPh₃)(CC)_n(η²-dppe)Fe(η⁵-C₅Me₅) (n = 3, 4) as well as the hexacarbonyl dicobalt adduct (4) of the hexatriynediyl complex 3₃. We show by cyclic voltammetry that the “electronic communication” between the organometallic endgroups and thereby the thermodynamic stability of the corresponding mixed-valent (MV) parent 3_n⁺ is strongly influenced by bridge extension or by complexation of the [Co₂(CO)₆] fragment. In the case of the hexatriynediyl complex, the MV complex 3₃⁺ or 4 can be isolated by performing the chemical oxidation of 3₃ at low temperature. Spectroscopic studies of this compound and of other stable oxidized redox congeners should now help us to unravel how bridge extension modifies the electronic communication between the different redox-active endgroups in this family of unsymmetrically-substituted polyynediyl compounds.     

Crystal structure of Fe(η-C5H5BCMe3)2 a “problem structure”

The complex Fe(η⁶-C₅H₅CMe₃)₂ crystallizes in the centrosymmetric triclinic space group P (C_i¹; No. 2) with unit cell dimensions of a 8.770(1) Å, b 8.878(1) Å, c 11.991(1) Å, 107.56(1)°, β 90.85(1)°, γ 90.13(1)°, V 890.0(2) ų and Z = 2. A full sphere of data was collected on a four-circle diffractometer. The structure was solved and refined to R 7.93% for all 3155 independent reflections and R 4.98% for those 2002 data with | F₀ | > 6σ. | F₀ |. The molecules lie on crystallographic inversion centers at 0, 0, 0 and 1/2, 0, 1/2; the crystallographic asymmetric unit therefore consists of two independent half molecules. The molecule centered at 0, 0, 0 (molecule “A”) is ordered and well-defined; that centered on 1/2, 0, 1/2 (molecule “B”)is probably disordered, as indicated by larger “thermal parameters” and a greater range of apparent interatomic distances. Discussion em phasizes the geometry of molecule A, which has precise C_i symmetry with Fe(1A)-B(1A) 2.297(4) Å and Fe(1A)-C(ring) distances ranging from 2.057(6) Å to 2.138(4) Å.     

The crystal structure of a phenyliminomethyldicyclopentadienyltitanium(III) complex, Cp2Ti-η-C6H5CN-2,6-(CH3)2C6H3

The crystal structure of Cp₂TiC₆H₅CN-2,6-(CH₃)₂C₆H₃ is reported. The iminoacyl ligand is η²-coordinated at the metal (Ti---C 2.096(4), Ti---N 2.149(4) Å). The cyclopentadienyl ligands show the normal bent Cp₂Ti structure.     

Darstellung,struktur und eigenschaften des dreikernigen titankomplexes (π-C2H5)2TiClOTi(π-C5H5)ClOTiCl(π-C5H5)2·CHCl3

The trinuclear titanium(IV) complex (π-C₅H₅)₂TiClOTi(π-C₅H₅)ClOTiCl(π-C₅H₅)₂ · CHCl₃ is formed by hydrolysis of (π-C₅H₅)₂TiCl₂ at pH > 3.5 and can be isolated in the crystalline state from the reaction of (π-C₅H₅)₂TiCl₂ with Ag₂O and water in chloroform. Its structure is determined by X-ray analysis.     

The redox behaviour of ferrocene derivatives : III. Ferrocenylacyl complexes (η-C5H5) Fe(η-C5H4-COER3 E = C, Si or Ge; R = Me or Ph

The electrochemical behaviour of the ferrocenylacyl derivatives [FcCOER₃] (E = C, Si or Ge; R = Me or Ph) is examined. One-electron oxidations to the substantially stable monocations [FcCOER₃]⁺ occur at potentials significantly higher than that observed with ferrocene, but only minor differences hold within the series, independent of the nature of both E and R. In contrast the EPR spectra of the monocations for E = C show that the unpaired electron resides mainly on the iron, whereas for E = Si or Ge the electron density is essentially localized on the C₅H₄COER₃ fragment.     

Synthesis and structure of the iron-substituted silylacetylene [(η-C5H5)Fe(CO)2SiMe2C]2 and its cobalt hexacarbonyl derivative [(η-C5H5)Fe(CO)2SiMe2C]2 · Co2(CO)6

A transition metal-substituted silylacetylene [(η⁵-C₅H₅)Fe(CO)₂SiMe₂C]₂, [FpMe₂SiC]₂ (I) was synthesized and characterized spectroscopically and structurally. I crystallized in the monoclinic space group P2₁/n, A = 13.011(3) Å B = 12.912(3) Å, C = 13.175(5) Å, β = 94.95(2). The acetylene linkage is reactive toward Co₂(CO)₈ to form I. Co₂(CO)₆ (II) which was also characterized spectroscopically and by single crystal X-ray diffraction. II crystallized in the orthorhombic space group Pbca, A = 17.64(2) Å, B = 14.225(10) Å, C = 24.49(2) Å.     

Structures of propionaldehyde, butyraldehyde, and pivalaldehyde complexes of the chiral rhenium fragment [(η-C5H5)Re(NO)(PPh3)]

The crystal structures of propionaldehyde complex (RS,SR)-(η⁵-C₅H₅)Re(NO)(PPh₃)(η²-O=CHCH₂CH₃)]⁺ PF₆⁻ (1b⁺ PF₆^s−; monoclinic, P2₁/c (No. 14), a = 10.166 (1) Å, b = 18.316(1) Å, c = 14.872(2) Å, β = 100.51(1)°, Z = 4) and butyraldehyde complex (RS,SR)-[(η⁵-C₅H₅)Re(NO)(PPh₃)(η²-O=CHCH₂CH₂CH₃)]⁺ PF₆⁻ (1c⁺PF₆⁻; monoclinic, P2₁/a (No. 14), a = 14.851(1) Å, b = 18.623(3) Å, c = 10.026(2) Å, β = 102.95(1)°, Z = 4) have been determined at 22°C and −125°C, respectively. These exhibit C O bond lengths (1.35(1), 1.338(5) Å) that are intermediate between those of propionaldehyde (1.209(4) Å) and 1-propanol (1.41 Å). Other geometric features are analyzed. Reaction of [(η⁵-C₅H₅)Re(NO)(PPh₃)(ClCH₂Cl)]⁺ BF₄⁻ and pivalaldehyde gives [(η⁵-C₅H₅)Re(NO)(PPh₃)(η²-O=CHC(CH₃)₃)]⁺BF₄⁻ (81%), the spectroscopic properties of which establish a π C O binding mode.