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This dissertation focuses on the expansion of ligand sets available to isolate new +2 ions of the rare earth metals, i.e., Sc, Y, and the lanthanides. In addition to their isolation, their reactivity and physical properties have also been investigated. Chapter 1 describes the basis of this dissertation research, i.e., the initial isolation of new Ln(II) ions using the (C5H4SiMe3)33− ligand set and the characterization of these new Ln2+ ions. Chapter 2 describes the use of the (C5Me4H)33− ligand set to isolate a new series of Ln2+ complexes and compares their properties to the (C5H4SiMe3)33− complexes. In the (C5H4SiMe3)33− ligand set, Dy adopts a 4f95d1 electron configuration while in the (C5Me4H)33− ligand set, Dy adopts a 4f10 electron configuration. Chapter 3 describes efforts to isolate the first C5Me5 complex of a new Ln2+ ion in heteroleptic Y2+ complexes of the form, [CpX2Y(NR2)]1−, where CpX = C5Me5 and C5Me4H, and study their properties. Chapter 4 describes the reactivity and reductive chemistry of rare earth metal allylcomplexes with benzoxazole. Appendix A describes the reactivity of the [(C5Me4H)3Ln]1− complexes for Ln = La and Ce with tert-butyl isocyanide including EPR spectroscopy. Appendix B describes efforts to synthesize and reduce other heteroleptic rare earth metal complexes by investigating the dynamic between ligand choice and the identity of the rare earth metal.

Aufgrund seiner reversiblen Redox-Chemie besitzt Cer außergewöhnliche Relevanz im Vergleich mit den anderen Seltenerdmetallen. Auf dem Gebiet der metallorganischen Chemie von vierwertigem Cer wurden jedoch erst in jüngerer Zeit große Fortschritte gemacht. Dies liegt insbesondere an der Schwierigkeit, vierwertiges Cer zu stabilisieren, was in großem Maße von der Ligandensphäre beeinflusst wird. Dieser Vortrag geht näher auf dieses Problem ein, indem Bildung und Stabilität von Cer(IV)-Komplexen untersucht werden. Ein besonderes Augenmerk liegt auf den Effekten unterschiedlicher Liganden und den elektrochemischen Eigenschaften. Zunächst wird die Synthese von neuartigen Cer(III)-Fluorenyl-Komplexen der Form FluCeR2(thf)x als potentiellen Vorstufen der Cer(IV)-Chemie vorgestellt sowie deren Liganden-Disproportionierungs-Reaktionen bei Raumtemperatur zu Flu2CeR(thf)x im Falle von Alkoholat-, Silanolat- und Pyrazolat-Liganden. Bei Kontakt mit halogenierenden Oxidationsmitteln erfolgte eine Reaktion zu Cer(III)-Spezies und 9-Halogenfluoren sowie 1,1‘-Bifluoren, die stöchiometrisch kontrolliert werden kann. Bei Verwendung des At-Komplexes Cp*2CeCl2K(thf)2 als Edukt gelang die Oxidation zu Komplexen des Typs Cp*2Ce(OR)2 mit Alkoholat- und Silanolat-Liganden sowie zu Cp*2Ce(OR)Cl mit Phenolat-Liganden. Wieder zeigte sich bei Raumtemperatur eine Umorganisation der Liganden, die in der Bildung der ersten Cer(IV)-Halbsandwich-Komplexe Cp*Ce(OR)3 mit R = SiPh3 und tBu resultierte. Cyclovoltammetrische Analysen der Komplexe offenbarten eine zunehmende Stabilisierung der Oxidationsstufe +IV in der Reihenfolge Phenolat < Silanolat < Alkoholat. Weiterhin zeigten die Halbsandwich-Komplexe verglichen mit den entsprechenden Sandwich-Komplexen ebenfalls eine stärkere Stabilisierung sowie eine eingeschränkte Reversibilität. Zuletzt wurde die Stabilitat von Organoer(IV)-Komplexen ausgehend von den Triscyclopentadienyl-Derivaten CpH/Me3CeR mit R = Cl, Br, I weitergehend untersucht. Der Chlorid-Komplex wurde als Edukt für Salzmetathese-Reaktionen genutzt, die für die Reste R = OMe, OEt, OiPr, OtBu, OCH2tBu, OSiMe3, OSiEt3, OSi(iPr)3 and OSiPh3 erfolgreich waren. Magnetische Messungen zeigten temperaturabhängigen Paramagnetismus (TIP) auf, mit positiven magnetischen Suszeptibilitäten. In cyclovoltammetrischen Experimenten verhielten sich die Halogenid- und Silanolatkomplexe chemisch und elektrochemisch reversibel, während Alkoholat-Komplexe Cyclovoltammogramme des EC- oder ECE-Typs aufwiesen. Die Formalpotentiale überspannen eine große Bandbreite und eröffnen damit die Möglichkeit, das elektrochemische Potential durch die Ligandenwahl zu steuern. Die Stabilisierung von Cer(IV) nahm in der Reihenfolge I < Br < Cl < Silanolat < Alkoholat sowie Cp < CpMe mit zunehmend Elektronen-donierenden Liganden zu.

International audience; Cationic [Ru(η 5-C5H5)(CH3CN)3] + complex, tris(acetonitrile)(cyclopentadienyl)ruthenium(II), gives rise to a very rich organometallic chemistry. Combined with diimine ligands, and 1,10-phenanthroline in particular, this system efficiently catalyzes diazo decomposition processes to generate metal-carbenes which undergo a series of original transformations in the presence of Lewis basic substrates. Herein, syntheses and characterizations of [CpRu(Phen)(L)] complexes with (large) lipophilic non-coordinating (PF6 − and BArF −) and coordinating N-TRISPHAT − anions are reported. Complex [CpRu(η 6-naphthalene)][BArF] [1][BArF] is readily accessible, in high yield, by direct counterion exchange between [1][PF6] and sodium tetrakis[3,5-bis(trifluoromethyl)phenyl]borate (NaBArF) salts. Ligand exchange of [1][BArF] in acetonitrile generated stable [Ru(η 5-C5H5)(CH3CN)3][BArF] [2][BArF] complex in high yield. Then, the desired [CpRu(Phen)(CH3CN)] [3] complexes were obtained from either the [1] or [2] complex in the presence of the 1,10-phenanthroline as ligand. For characterization and comparison purposes, the anionic hemilabile ligand TRISPHAT-N (TTN) was introduced on the ruthenium center, from the complex [3][PF6], to quantitatively generate the desired complex [CpRu(Phen)(TTN)] [4] by displacement of the remaining acetonitrile ligand and of the PF6 − anion. Solid state structures of complexes [1][BArF], [2][BArF], [3][BArF], [3][PF6] and [4] were determined by X-ray diffraction studies and are discussed herein.

Following the synthesis of [Zn(η-CMe)] (in short [ZnCp ]) many complexes of the directly bonded Zn-Zn unit were prepared and characterized, leading to the recognition of an isolobal analogy between the Zn-Zn bond and the molecule of dihydrogen. Prompted by these results, we have investigated η-Zn-coordination of [ZnCp] and [ZnPh] (Cp = CH, Ph = CH) to several selected transition metal fragments and report herein the results of a QTAIM study of complexes [(ZnR)Fe(CO)], [(η-ZnR)M(CO)] and [(η-ZnR)Pd(PR′)] (for R = Cp, Ph; M = Cr, Mo, W; and R′ = F, H, Me). A decrease of ρ, ∇ρ and delocalization indexes δ(Zn,Zn), relative to corresponding values in the parent molecules of [ZnCp] and [ZnPh], accompanied dizinc coordination. In most cases the computed δ(Zn,Zn) parameters were indicative of significant electron density sharing between the two Zn atoms. Nevertheless, the interaction with [Fe(CO)] resulted in oxidative cleavage of the coordinated Zn-Zn bond, due to high π backdonation to the σ∗ Zn MO as deduced from the δ(M,O) index. The Zn-Zn bond critical points identified in our study are discussed. The computed Zn-Zn contacts concentrate in the range 2.44–2.58 Å, and we propose that this interval corresponds to elongated dizinc bonds.

Benzofuran (BF), benzothiophene (BT), indole (IN), dibenzofuran (DBF), dibenzothiophene (DBT), and carbazole (CA) are typical heterocyclic aromatic compounds (NSO-HETs), which can coexist with polycyclic aromatic hydrocarbons (PAHs) in combustion and pyrolysis conditions. In this work, quantum chemical calculations were carried out to investigate the formation of DBF, DBT, and CA from the reactions of BF, BT, and IN with a cyclopentadienyl radical (CPDyl) by using the hybrid density functional theory (DFT) at the MPWB1K/6-311+G(3df,2p)//MPWB1K/6-31+G(d,p) level. The rate constants of crucial elementary steps were deduced over 600&minus, 1200 K, using canonical variational transition state theory with a small-curvature tunneling contribution (CVT/SCT). This paper showed that the production of DBF, DBT, and CA from the reactions of BF, BT, and IN with CPDyl involved six elementary steps: the addition reaction, ring closure, the first H shift, C&ndash, C cleavage, the second H shift, and elimination of CH3 or H. The cleavage of the C&ndash, C bond was regarded as the rate-determining step for each pathway due to the extremely high barrier. The 1-methyl substituted products were more easily formed than the 4-methyl substituted products. The main products were DBF and 1-methyl-DBF, DBT and 1-methyl-DBT, and CA and 1-methyl-CA for reactions of BF, BT, and IN with CPDyl, respectively. The ranking of DBF, DBT, and CA formation potential was as follows: DBT and methyl-DBT formation &gt, DBF and methyl-DBF formation &gt, CA, and methyl-CA formation. Comparison with the reaction of naphthalene with CPDyl indicated that the reactions of CPDyl attacking a benzene ring and a furan/thiophene/pyrrole ring could be inferred to be comparable under high temperature conditions.

The reactivity of the yttrium trichloride complex [Cl3Y{(μ3-NH)3Ti3(η5-C5Me5)3(μ3-N)}] (2) with a variety of main-group metal cyclopentadienyl reagents [M(C5H3R1R2)] (M = Li, Na, K, Tl) or [Mg(C5H5)2] has been investigated. Treatment of 2 with one equivalent of [Na(C5H5)] or [K(C5H4SiMe3)] gives the monocyclopentadienyl derivatives [(η5-C5H4R)Cl2Y{(μ3-NH)3Ti3(η5-C5Me5)3(μ3-N)}] (R = H (3), SiMe3 (4)). Analogous reaction of 2 with lithium [Li(C5H3R1R2)] or thallium [Tl(C5H5)] reagents (1 or 2 equivalents) leads to complexes [(η5-C5H3R1R2)2Y(μ-Cl)2M{(μ3-NH)3Ti3(η5-C5Me5)3(μ3-N)}] (M = Li, R1 = R2 = H (5), R1 = H, R2 = SiMe3 (6), R1 = R2 = SiMe3 (7); M = Tl, R1 = R2 = H (8)). Complex 2 reacts with [Mg(C5H5)2] to yield the ionic compound [(μ-Cl)3Mg2{(μ3-NH)3Ti3(η5-C5Me5)3(μ3-N)}2][{Y(η5-C5H5)2Cl}2(μ-Cl)] (9). In contrast to the metathesis of chloride ligands, the reaction of 2 with the lithium indenyl derivative [Li(C9H7)] at room temperature produces C9H8 and the precipitation of [Li(μ-Cl)3Y{(μ3-N)(μ3-NH)2Ti3(η5-C5Me5)3(μ3-N)}] (10). Crystallization of 10 in pyridine affords the lithium-free [Cl2(py)2Y{(μ3-N)(μ3-NH)2Ti3(η5-C5Me5)3(μ3-N)}] (11) complex. The X-ray crystal structures of 6 and 11 have been determined., Ministerio de Economía y Competitividad de España, Universidad de Alcalá

A series of six indenyl molybdenum compounds bearing a thiophenyl function in the side chain were prepared and characterized by analytical and spectroscopic methods. The structures of [(eta(5)-C9H6CH2C4H3S)(eta(3)-C3H5)Mo(CO)(2)] and [(eta(5)-C9H6CH2C4H3S)Mo(CO)(2)(bpy)][BF4] were determined by single-crystal X-ray diffraction. The compounds bearing N,N-chelating ligands exhibit increased cytotoxic activity against human leukemia cell lines MOLT-4; up to two orders of magnitude lower IC50 values were observed compared to analogues with unsubstituted indenyl, which clearly demonstrates the strong effect of the indenyl ligand modification on the biological activity of the molybdenum(ii) compounds. The highest cytostatic potential was observed for the complex bearing 4,7-diphenyl-1,10-phenanthtoline [(eta(5)-C9H6CH2C4H3S)Mo(CO)(2)(Ph(2)phen)][BF4] with IC50 (MOLT-4) = 0.19 +/- 0.02 mu M. Detailed regulation of the molecular and cellular mechanism by this derivative was investigated on the lung carcinoma cell line A549 and compared with the lung fibroblast cell line MRC-5. Rather unusual differences in the effects on tumor and non-tumor cell lines provide a unique insight into the cytostatic action of molybdenum(ii) complexes. Byla připravena série 6 inynylových komplexů molybdenu s thiofenovou funkční skupinou v postranním řetězci. Tyto sloučeniny byly charakterizovány analytickými a spektroskopickými metodami.Struktura 3 komplexů byla stanovena pomocí RTG difrakční analýzy. Sloučeniny s N,N-chelátujícími ligandy byly podrobeny testům citotoxické aktivity vůči leukemickým buňkám MOLT-4.

In this review article we present all the recent research on stacking interactions of aromatic ligands that coordinate to transition metals through their π-electrons (η-coordination). These studies were mostly based on searching the crystal structures from the Cambridge Structural Database (CSD) and on quantum chemical calculations. Stacking interactions between coordinated and uncoordinated benzene reach the energy of −4.40 kcal/mol, while the strongest calculated staking between two coordinated benzenes has the energy of −4.01 kcal/mol; this is significantly stronger than stacking between two uncoordinated benzenes (−2.73 kcal/mol). It was determined that in crystal structures both coordinated benzene and coordinated cyclopentadienyl anion form stacking interactions that dominantly have large horizontal displacements (more than 4.5 Å). This dominance is caused by the relatively strong stacking interactions at large displacements between benzene or Cp ligands in sandwich compounds, while for half-sandwich compounds they are supported by additional interactions of the other (usually branched) ligands. Larger aromatic ligands, tropylium and cyclooctatetraenide, almost exclusively form stacking interactions with large horizontal displacements. Methyl substituted benzene and Cp ligands dominantly form stacking interactions in combination with C–H/π interactions. Moreover, there is an interplay of stacking and aromatic C–H/π interactions in the CSD crystal structures, both interactions being important energy contributors to the stability of supramolecular systems. Stacking interactions of η-coordinated aromatic ligands are important in materials science, crystal engineering and medicinal chemistry, primarily in the application of ruthenium-arene complexes, where they determine the strength of bonding of these complexes to the DNA. Supplementary material: [http://cherry.chem.bg.ac.rs/handle/123456789/4031]

Treatment of the tris(cyclopentadienyl) thorium(III) complex [Th(η5-Cp′′)3] [1, Cp′′ = C5H3-1,3-(SiMe3)2] with the N-heterocyclic olefin H2C=C(NMeCH)2 (2) reproducibly produces the thorium(IV)-methyl derivative [Th(η5-Cp′′)3(Me)] (3) along with MeImCH2CH2ImMe (Im = imidazole). The reaction mechanism, which is consistent with 1H NMR spectroscopic observations, is proposed to proceed via: (i) coordination of 2 to 1; (ii) one-electron transfer from thorium to 2; (iii) N-methyl cleavage and transfer to thorium to give 3; (iv) coupling of the resulting imidazolium radical by-product to give MeImCH2CH2ImMe. Complex 3 has been characterised by single crystal X-ray diffraction, multi-nuclear NMR and IR spectroscopies, and elemental analyses, and MeImCH2CH2ImMe by 1H NMR spectroscopy and mass spectrometry.

A novel water soluble organometallic compound, [RuCp(mTPPMSNa)(2,2′-bipy)][CF 3 SO 3 ] ( TM85 , where Cp = η 5 -cyclopentadienyl, mTPPMS = diphenylphosphane-benzene-3-sulfonate and 2,2′-bipy = 2,2′-bipyridine) is presented herein. Studies of interactions with relevant proteins were performed to understand the behavior and mode of action of this complex in the biological environment. Electrochemical and fluorescence studies showed that TM85 strongly binds to albumin. Studies carried out to study the formation of TM85 which adducts with ubiquitin and cytochrome c were performed by electrospray ionization mass spectrometry (ESI-MS). Antitumor activity was evaluated against a variety of human cancer cell lines, namely A2780, A2780cisR, MCF7, MDAMB231, HT29, PC3 and V79 non-tumorigenic cells and compared with the reference drug cisplatin. TM85 cytotoxic effect was reduced in the presence of endocytosis modulators at low temperatures, suggesting an energy-dependent mechanism consistent with endocytosis. Ultrastructural analysis by transmission electron microscopy (TEM) revealed that TM85 targets the endomembranar system disrupting the Golgi and also affects the mitochondria. Disruption of plasma membrane observed by flow cytometry could lead to cellular damage and cell death. On the whole, the biological activity evaluated herein combined with the water solubility property suggests that complex TM85 could be a promising anticancer agent.

Treatment of N,N′-diisopropylcarbodiimide with sodium cyclopentadienide (NaCp) in a molar ratio of 1:1 in THF solution resulted in formation of the unexpected dinuclear sodium half-sandwich complex [NaC5H3{C(NHiPr)(=NiPr)}2-1,2]2 (1) as colorless crystals in low yield. The newly formed ligand, which belongs to the group of 6-aminofulvene-2-aldiminate ligands, coordinates to sodium in an η5-coordination mode via the cyclopentadienyl ring. Dimerization occurs through additional chelating κN,N′-coordination of the amidine substituents. The NMR data of 1 indicated a slow dimer/monomer equilibrium in solution. A serendipitously isolated hydrolysis product, {µ-(iPrNH)2C=O}2[NaC5H3{C(NHiPr)(=NiPr)}2-1,2]2 (2), contains the new 6-aminofulvene-2-aldiminate ligand in the N,N′-chelating coordination mode with the cyclopentadiene ring being uncoordinated. In this case, dimerization occurs through the presence of two bridging neutral N,N′-diisopropylurea ligands. Both compounds have been structurally characterized by single-crystal X-ray diffraction.

7 páginas, 3 figuras, 6 esquemas., The synthesis of a series of rhodium and iridium complexes bearing bulky cyclopentadienyl or hydro(trispyrazolyl)borate ligands is described. The rhodium cyclopentadienyl and hydrotris(pyrazolyl)borate diene compounds, [(η5-C5Me4But)Rh(η4-2,3-MeRC4H4] (R = H, 1; Me, 2) and TpMsRh(η4-2,3-MeRC4H4) (R = H, 3; Me, 4; TpMs is hydrotris(3-mesitylpyrazol-1-yl)borate), respectively, have been prepared from the corresponding Rh(I) diene precursors and Zn(C5Me4But)2 (for 1 and 2), or TlTpMs (for 3 and 4), as effective C5Me4But or TpMs transfer reagents. In contrast with these results, attempts to obtain a bis(ethylene) derivative of the TptolIr(I) unit (Tptol stands for hydrotris(3-p-tolylpyrazol-1-yl)borate) have provided instead the Ir(III) complex [(κ4-N,N′,N″,C-Tptol)-Ir(C2H5)(C2H4)] (5), whose formation requires C–H bond activation of a molecule of ethylene and of one of the Tptol p-tolyl substituents. In refluxing toluene 5 experiences metalation of a second p-tolyl substituent to give [(κ5-N,N′,N″,C,C′-Tptol)-Ir(C2H4)] (6), which features unusual κ5-Tptol coordination. The latter compound reacts with carbon monoxide to yield the corresponding carbonyl, 7., Financial support from the Spanish Ministerio de Educación y Ciencia (MEC) (Project No. CTQ2007-62814) and Consolider-Ingenio 2010 (No. CSD2007-00006) (FEDER support), the Junta de Andalucía (Project Nos. FQM-3151 and FQM-672) is gratefully acknowledge. A.C.E. and J.E.V.V. thanks the CONACYT (Ref. No. 229340) and the MEC (F.P.U.) for research grants.

Vibronic coupling, electron–phonon interaction, constants of Jahn–Teller molecules, C5H5 and C5D5, are computed as matrix elements of the electronic operator of the vibronic coupling operator using the electronic wave functions calculated by generalized restricted Hartree–Fock (GRHF) and state-averaged complete active space self-consistent-field (CASSCF) methods. The calculated values of vibronic coupling constants for C5H5 and C5D5 agree well with the experimental values. Vibronic coupling density analysis can explain the isotope effect on the vibronic coupling from view of the electronic and vibrational structures. Changes of the vibrational modes as well as the frequencies upon the deuteration can affect the vibronic coupling. Vibronic density analysis provides a local picture of the coupling in a molecule, and it enables us to control the coupling. This could open a way to engineering of the vibronic coupling, vibronics.

A new family of eight ruthenium(II)-cyclopentadienyl bipyridine derivatives, bearing nitrogen, sulfur, phosphorous and carbonyl sigma bonded coligands, has been synthesized. Compounds bearing nitrogen bonded coligands were found to be unstable in aqueous solution, while the others presented appropriate stabilities for the biologic assays and pursued for determination of IC50 values in ovarian (A2780) and breast (MCF7 and MDAMB231) human cancer cell lines. These studies were also carried out for the [5: HSA] and [6: HSA] adducts (HSA=human serum albumin) and a better performance was found for the first case. Spectroscopic, electrochemical studies by cyclic voltammetry and density functional theory calculations allowed us to get some understanding on the electronic flow directions within the molecules and to find a possible clue concerning the structural features of coligands that can activate bipyridyl ligands toward an increased cytotoxic effect. X-ray structure analysis of compound [Ru(η(5)-C5H5)(bipy)(PPh3)][PF6] (7; bipy=bipyridine) showed crystallization on C2/c space group with two enantiomers of the [Ru(η(5)-C5H5)(bipy)(PPh3)](+) cation complex in the racemic crystal packing.

Mixed μ-phosphido or μ-thiolato μ-halo-dimolybdenum(III) compounds [Mo 2 Cp 2 (μ-SMe) 2 (μ-X)(μ-Y)] (X = PPh 2 , Y = Cl ( 1 ); X = SCH 3 , Y = Br ( 3 ), I( 4 )) have been studied. Syntheses and X-ray structures of the new bromo and iodo analogues of [Mo 2 Cp 2 (μ-SMe) 3 (μ-Cl)] ( 2 ) are reported. While preparing 3 a side-product 5 was obtained and structurally characterised as the Mo 5 system [{Mo 2 Cp 2 Br(μ-O)(μ-SMe) 2 } 2 (μ-MoO 4 )], containing a {Mo IV –Mo IV –O–(Mo VI O 2 )–O–Mo IV –Mo IV } unit. The influence of the bridging groups on the structures and electrochemical behaviour of the complexes [Mo 2 Cp 2 (μ-SMe) 2 (μ-X)(μ-Y)] 1 – 4 has been investigated. In MeCN–[NBu 4 ][PF 6 ] the first oxidation of [Mo 2 Cp 2 (μ-SMe) 2 (μ-PPh 2 )(μ-Cl)] ( 1 ) is quasi-reversible, contrasting with the essentially irreversible first oxidation of the thiolate analogue [Mo 2 Cp 2 (μ-SMe) 3 (μ-Cl)] ( 2 ) under similar conditions. The effects of lowering the temperature or increasing the scan rate on the oxidation of 1 were examined: the initial quasi-reversible oxidation at first became irreversible but at still higher scan rates or lower temperatures the oxidation was again quasi-reversible. This suggests that the oxidation of 1 in MeCN is followed by reversible coordination of acetonitrile to afford the species [Mo 2 Cp 2 (μ-SMe) 2 (μ-PPh 2 )(Cl)(MeCN)] + ( 7 + ). Cyclic voltammetry of [Mo 2 Cp 2 (μ-SMe) 3 (μ-Y)](Y = Br ( 3 ) or I ( 4 )) showed two quasi-reversible diffusion-controlled oxidation steps in CH 2 Cl 2 –[NBu 4 ][PF 6 ] or thf–[NBu 4 ][PF 6 ]. In acetonitrile, the fast loss of the halide ligands results in the formation of [Mo 2 Cp 2 (μ-SMe) 3 (MeCN) 2 ] + species.

The non-vicinal methyl-phenyl-substituted zirconocene dichlorides meso-and rac-[Zr{η5-(1-Ph-3-Me-C5H3)}2Cl2] and [Zr(η5-C5H5){η5-(1-Ph-3-Me-C5H3)}Cl2] have been isolated by transmetallation of the lithium salt Li(1-Ph-3-Me-C5H3) to ZrCl4(THF)2 and [Zr(η5-C5H5)Cl3 · DME] (DME = dimethoxyethane), respectively. Similar transmetallation of the lithium salt Li2[(Me-Ph-C5H2SiMe2)2O] to MCl4 gave the ansa-metallocenes [M{η5-(Me-Ph-C5H2SiMe2)2O}Cl2] (M = Zr, Hf) for which the meso- and rac-diastereomers were separated. The dimethyl and dibenzyl derivatives of these metallocenes were also prepared and the structure of all of these compounds determined by NMR spectroscopy. The molecular structure of rac-[Zr{η5-(2-Me-4-Ph-C5H2SiMe2)2O}Cl2] was determined by single crystal X-ray diffraction methods. The activity of the dichlorometallocenes/MAO catalysts for ethene and propene polymerization was evaluated., Ministerio de Educación, Cultura y Deporte, Repsol-YPF

The reaction of CpMoCl2 with diazadiene ligands RNCHCHNR (R2dad) affords the corresponding paramagnetic complexes CpMoCl2(R2dad) (R=Ph, 1; p-Tol, 2; C6H3Pr2i-2,6, 3; and Pri, 4). All compounds have been characterized by EPR spectroscopy and have been investigated by cyclic voltammetry. They display one-electron oxidation and reduction processes, these being reversible or irreversible depending on the nature of R. The irreversibility of the reduction wave is due to a chemical follow-up process which consists of chloride loss from the reduced product. This phenomenon is suppressed in the presence of excess chloride in solution. An X-ray structure of 3 verifies the mononuclear nature of the compound and the chelating mode of the dad ligand, the MoN2C2 ring being essentially planar. The NC and CC bond distance pattern suggests the important contribution of an enediamido Mo(V) limiting form. In the presence of 1-bromoethylbenzene, complexes 1–4 catalyze the controlled/‘living’ radical polymerization of styrene. Complex 3 also leads to a controlled/‘living’ radical polymerization of styrene in the presence of AIBN (α,α-azoisobutyronitrile) as a radical generator. Therefore, this is the second example of a compound which is capable of controlling the styrene radical polymerization under both ATRP and SFRP conditions.

In this work we report the synthesis of some organolanthanide compounds which were identified as LnCl2Cp(PzA)2, Ln = Nd, Sm, Eu and Tb, Cp = cyclopentadienyl and PzA = pirazinamide, by elemental analyses, complexometric titration with EDTA, thermal analyses and IR spectra. Thermal analysis and infrared spectra indicated that the coordination of the pyrazinamide to the lanthanide ions was made by the O atom of the carbonyl group and by one or both N atoms of the pyrazinamide ring. This class of compound showed catalytic activity of ca. 4.0 to 6.4 kgPE molLn-1 h-1 bar-1, in ethylene polymerization, using methylaluminoxane as cocatalyst. The resulting polyethylene presented low crystallinity (20%).

A new family of “FeII(η5-C5H5)” half sandwich compounds bearing a N-heteroaromatic ligand coordinated to the iron center by a nitrile functional group has been synthesized and fully characterized by NMR and UV–Vis spectroscopy. X-ray analysis of single crystal was achieved for complexes 1 and 3, which crystallized in the monoclinic P21/c and monoclinic P21/n space groups, respectively. Studies of interaction of these five new complexes with plasmid pBR322 DNA by atomic force microscopy showed very strong and different types of interaction. Antiproliferative tests were examined on human leukemia cancer cells (HL-60) using the MTT assay, and the IC50 values revealed excellent antiproliferative activity compared to cisplatin.

The IR intensities of the CH vibrational modes of a hydrocarbon fragment bonded to a metal atom are a useful probe to evaluate the charge distribution on the fragment. The values of R, the ratio of the overall CH bending and CH stretching IR intensities of the cyclopentadienyl ligand, are reported for several organometallic complexes containing the η5-C5H5M unit. The parameter R is related to several properties of the complexes, such as the ionic charge, the nature of the metal and of the ancillary ligands, the CH bending force constant and to the solid-state structure.

Reactions of [MCp*Cl4] (M=Mo, W; Cp*=η5-C5Me5) with salts of the N,N-diethyldithiocarbamate [Et2dtc]− and O,O′-diethyldithiophosphate [Et2dtp]− anions yield the paramagnetic metal(V) complexes [MCp*Cl3(Et2dtc)] (M=Mo, W) and [MCp*Cl3(Et2dtp)] (M=Mo, W), respectively. Hydrolytic oxidation of both dithiocarbamate–molybdenum complexes with aqueous hydrogen peroxide leads to η2-coordinated peroxo compounds [MoCp*Cl(O–O)O], which were also obtained from [MoCp*Cl4]. The related complexes [MCp′Cl(O–O)O] (M=Mo, Cp′=η5-C5H5; M=W, Cp′=η5-C5Me5) were isolated in a similar way. Reduction of a THF solution of [MoCp*Cl4] with one equivalent of 10% Na/Hg followed by the addition of one equivalent of ammonium dithiophosphate gives [MoCp*Cl2(Et2dtp)] which was also obtained via the reaction of [MoCp*Cl3(Et2dtp)] with MeMgCl, whereas reduction with three equivalents of Na/Hg in the presence of CNtBu leads to the molybdenum(II) complex [MoCp*(Et2dtp)(CNtBu)2] in high yield. All these compounds were characterized by elemental analysis, IR, 1H- and 13C-NMR spectroscopy, magnetic susceptibility measurements and the molecular structures of [Mo(η5-C5H5)Cl(O–O)O] and [Mo(η5–C5Me5)Cl3{η2-S2P(OEt)2}] were determined by X-ray diffraction studies., Consiglio Nazionale delle Ricerche (Rome)

The functionalized silylated cyclopentadienyl molybdenum and tungsten complexes [MCpCl(CO)3H] (M=Mo, W; CpCl=η5-C5H4SiMe2Cl) are prepared easily from the reaction of [M(CO)3(NCMe)3] with C5H5SiMe2Cl in refluxing THF, via C–H activation and H transfer to the metal centre. Metathetical replacement of hydride by chloride is readily achieved when their methylene chloride solutions are treated with a few milliliters of CCl4 to give the chloro complexes [MCpCl(CO)3Cl] (M=Mo, W). The chloro–molybdenum complexes react with 1/2 equivalent of deoxygenated water to give the corresponding dinuclear complexes [{Mo(CO)3X}2(μ-CpOCp)], (X=H, Cl; CpOCp=η5-C5H4-SiMe2-O-SiMe2-η5-C5H4), whereas their reaction with one equivalent of anhydrous LiOH in toluene leads to selective substitution of the silicon-bonded chlorine atom to give the hydroxo complexes [MoCpOH(CO)3X] (X=H, Cl; CpOH=η5-C5H4SiMe2OH). These hydroxosilyl complexes can be transformed into the dinuclear compounds [{Mo(CO)3X}2(μ-CpOCp)] by heating (50°C, 2 h) or by their reaction with one equivalent of the respective hydrido and chloro derivatives [MoCpCl(CO)3X]. Total decarbonylation of the hydrido compounds results from oxidation with a stoichiometric amount of PCl5 to give the paramagnetic molybdenum(V) and tungsten(V) complexes [MCpClCl4] (M=Mo, W). Reactions of these complexes with one equivalent of NH2R in the presence of NEt3 yield the imido derivatives [MCpCl(NR)Cl2] (M=Mo, R=2,6-Me2-Ph; M=W, R=tBu) and subsequent oxidation of the tungsten complex with 1/2 equivalent of PCl5 gives [WCpCl(NtBu)Cl3]. Reduction of [MoCpClCl4] with two equivalents of Na/Hg gives the dinuclear molybdenum(III) complex [MoCpCl]2(μ-Cl)4. All of the reported compounds were characterized by elemental analysis and 1H- and 13C NMR-spectroscopy., The authors acknowledge DGICYT (project PB92-0178-C) for financial support.

Some pentamethylcyclopentadienyl ruthenium(II) diphosphine chloride complexes have been prepared by ligand exchange starting with the parent triphenylphosphine derivatives and their reactivities compared with those of the corresponding cyclopentadienyl compounds. The pentamethyl ligand causes a greater extent of asymmetric induction when the (R)-prophos and (R)-phenphos ligands are used as well as a higher lability of the stereochemistry at the stereogenic ruthenium centre. A shift of about 200 mV in the oxidation potential is caused by the substitution at the penta-hapto ligand. The order of basicity of the diphosphine ligands was also evaluated and was found to be consistent with previous determinations. The crystal structure of(eta(5)-C5Me5)Ru {(S,S)-chiraphos}Cl shows a coordination around the ruthenium atom similar to that found for the (eta(5)-C5H5)Ru{(S,S) -chiraphos}Cl complex. (C) 1998 Elsevier Science S.A. All rights reserved.

This paper describes the synthesis and characterization of alkylidene pentamethylcyclopentadienyl imido tungsten(VI) complexes via α-hydrogen abstraction processes from suitable alkyl derivatives. Reaction of WCp*Cl4 with one equivalent of NH2R (R=tBu, 2,6-Me2–C6H3), two equivalents of NEt3 and subsequent oxidation with PCl5 affords the pentamethylcyclopentadienyl imido tungsten derivatives, WCp*(NtBu)Cl3 2 and WCp*(N-2,6-(Me2)–C6H3)Cl3 4. Alkylation of complexes 2 and 4 with 1.5 equivalents of ZnMe2 under appropriate conditions yields the trimethyl derivatives WCp*(NtBu)Me3 5 and WCp*(N-2,6-(Me2)–C6H3)Me3 6. Exposure of complex 6 to sun-light leads to the formation of WCp*(N-2,6-(Me2)–C6H3)(CH2)Me 7 through a α-hydrogen abstraction process. Analogously, complex 2 reacts with 1.5 equivalents of Mg(CH2Ph)-(thf)2 or three equivalents of LiCH2SiMe3 to give the alkylidene complexes, WCp*(NtBu)(CHPh)(CH2Ph) 8 and WCp*(NtBu)(CHSiMe3)Cl 9, through a spontaneous α-hydrogen abstraction process in these cases.

The new ferrocenic polyphosphines [C 5 Me 3 -1,2-(PPh 2 ) 2 ](C 5 H 5 )Fe 2 , [C 5 Me 3 -1,2-(PPh 2 ) 2 ] 2 Fe 3 , [C 5 Me 3 -1,2-(PPh 2 ) 2 ][C 5 Me 4 (PPh 2 )]Fe 4 and polythioethers [C 5 Me 3 -1,2-(SCH 2 CH 2 CH 3 )2] 2 Fe 6 and [C 5 Me 3 -1,2-(SCH 2 CH 2 CH 3 ) 2 ](C 5 H 5 )Fe 7 have been prepared. The X-ray crystal structures of 3 and 6 have been determined. Some aspects of the reactivity of compounds 2 , 3 and 4 are reported (P(III)→P(V) transformation, chelating properties) as well as the X-ray structure of [C 5 Me 3 -1,2-(PPh 2 ) 2 W(CO) 4 ](C 5 H 5 )Fe 15 .

Trimethylsilylcyclopentadiene-siloxy ethers Me(3)SiC(5)H(4)(CH2),OSiMe(3) (n = 2, 3) react with TiCl4 to give (2-(cyclopentadienyl)-eth-1-oxy)titanium dichloride, [[eta(5): eta(1)-C5H4(CH2)(2)O]TiCl2](2) and (3-(cyclopentadienyl)-prop-1-oxy)titanium dichloride [eta(5): eta(1)- C5H4(CH2)(3)O]TiCl2, by release of two equivalents of Me(3)SiCl. Molecular structure determination shows that [[eta(5): eta(1)- C5H4(CH2)(2)O]TiCl2](2) is dimeric in the solid state with the alkoxide function bridging two titanium centers, whereas [eta(5): eta(1)- C5H4(CH2)(3)O]TiCl2 is a monomer with a bidentate cyclopentadienyl-alkoxide ligand. [[eta(5): eta(1)-C5H4(CH2)(2)O]TiCl2](2) crystallizes in the triclinic space group with a = 7.702(1) Angstrom, b = 7.942(2) Angstrom, c = 8.251(1) Angstrom, alpha = 71.39(1)degrees beta = 89.92(1)degrees, gamma = 61.25(2)degrees, V = 412.27(16) Angstrom(3) and Z = 1. The basic structure consists of a dimer molecule with a crystallographic center of inversion, coupled by two Ti-O-Ti bridges. Crystals of [eta(5):eta(1)-C5H4(CH2)(3)O]TiCl2 are triclinic, space group with a = 8.194(1), b = 11.002(1), c = 11.192(1) Angstrom, alpha = 84.339(5), beta = 88.035(5), gamma = 76.256(6)degrees, V = 975.2 Angstrom(3) and Z = 4. Two crystallographically independent molecules are present in the asymmetric unit.

The reaction of [(eta(5)-C7H7)Fe(CO)(3)](-) with [(eta(4)-C8H12)(eta(5)-C5H5)Pt](+) leads to the formation of syn-[(mu-eta(3);eta(2)-C7H7)Fe(CO)(3)Pt(eta(2),sigma(1)-C8H12-H-12-C5H5)] (1), a bridged cycloheptatrienyl complex with an Fe-Pt bond. In solution two structural isomers of 1 are present in roughly the same concentration, whereas in the solid only one isomer is detected. Both isomers are fluxional and undergo ring whizzing of the C7H7 ring. The slow-exchange limiting NMR spectrum of the cycloheptatrienyl unit cannot be reached even at low temperature (similar to 173 K). The C7H7 ring has an uncoordinated double bond and the cyclopentadienyl unit is linked to the C8H12 ring through an sp2 carbon; the resulting cyclooctenyl unit is coordinated eta(2),sigma(1) to platinum. The C5H5 transfer, mediated by platinum, can be of interest in the synthesis of the skeleton of natural occurring products. Crystal data for syn-[(mu-eta(3);eta(2)-C7H7)Fe(CO)(3)Pt(eta(2),sigma(1)-C8H12-C5H5)]: monoclinic, space group C2/c (No.15), a=45.197(6),b=13.306(1), c=7.509(1) Angstrom, beta=92.95(1)degrees, V=4509.8(9) Angstrom(3), Z=8 R=0.033, R(w)=0.080.

Anticancer activity of the new [Ru(η(5)-C5H5)(PPh3)(Me2bpy)][CF3SO3] (Me2bpy = 4,4'-dimethyl-2,2'-bipyridine) complex was evaluated in vitro against several human cancer cell lines, namely A2780, A2780CisR, HT29, MCF7, MDAMB231 and PC3. Remarkably, the IC50 values, placed in the nanomolar and sub-micromolar range, largely exceeded the activity of cisplatin. Binding to human serum albumin, either HSA (human serum albumin) or HSA(faf) (fatty acid-free human serum albumin) does not affect the complex activity. Fluorescence studies revealed that the present ruthenium complex strongly quench the intrinsic fluorescence of albumin. Cell death by the [Ru(η(5)-C5H5)(PPh3)(Me2bpy)][CF3SO3] complex was reduced in the presence of endocytosis modulators and at low temperature, suggesting an energy-dependent mechanism consistent with endocytosis. On the whole, the biological activity evaluated herein suggests that the complex could be a promising anticancer agent.

Reacting tetrabenzo[a,c,g,i]fluorenyllithium {TbfLi(THF)(4) (1)} with TiCl(3)(THF)(3) (2) leads to the formation of the eta(5)-tetrabenzo[a,c,g,i]fluorenyltitanium(III) derivative TbfTiCl(2)(THF) (3), which can be conveyed to the titanium(IV)complex TbfTiCl(3) (4) by oxidative chlorination with CCl(4). Subsequent reaction with various lithium phenoxides gives a series of titanium complexes of the type TbtTiCl(2)(OAr) (Ar = 4-(t)BUC(6)H(4) (5), 2,6-Me(2)C(6)H(3) (6), 2,4,6-Me(3)C(6)H(2) (7), 2,6-(i)PrC(6)H(3) (8), 2,6-Ph(2)C(6)H(3) (9)). Furthermore, 3 was reacted with radicals or radical-generating peroxides to form the complexes TbfTiCl(2)TEMPO (10) and TbfTiCl(2)O(t)Bu (11). All compounds were characterized by IR, MS, and NMR measurements and X-ray crystallography. Finally, compounds 6, 8, 9, and 10 were subjected to ethylene polymerization experiments using d-MAO. The activities increase in the following order [kG(PE)mol(Ti)(-1) h(-1) bar(-1)]: 6 (320)

This paper describes a substantial enhancement of the aminopyridinato ligand stabilized early transition metal chemistry by introducing the sterically very demanding 2,6-dialkylphenyl substituted aminopyridinato ligands derived from (2,6-diisopropylphenyl)-[6-(2,6-dimethylphenyl)-pyridin-2-yl]-amine (1a-H, ApH) and (2,6-diisopropylphenyl)-[6-(2,4,6-triisopropylphenyl)-pyridin-2-yl]- amine (1b-H, Ap*H). The corresponding bis aminopyridinato zirconium dichloro complexes, [Ap(2)ZrCl(2)] (3a) and [Ap(2)*ZrCl2] (3b) and the dimethyl analogues, [Ap(2)ZrMe(2)] (4a) and [Ap(2)*ZrMe2] (4b) (Me = methyl) were synthesized, using standard salt metathesis routes. Single-crystal X-ray diffraction was carried out for the dichloro derivatives. Both zirconium metal centers have a distorted octahedral environment with a cis-orientation of the chloride ligands in 3a and a closer to trans-arrangement in 3b. The dimethyl derivatives are proven to be highly active ethylene polymerization catalysts after activation with [R2N(Me)H][B(C6F5)(4)] (R = C16H33-C18H37). During attempted co-polymerizations of alpha-olefins (propylene) and ethylene high activity and selectivity for ethylene and nearly no co-monomer incorporation was observed. Increasing the steric bulk of the ligand going from (2,6-dimethylphenyl) to (2,4,6-triisopropylphenyl) substituted pyridines, switches the catalyst system from producing long chain alpha-olefins to polymerization of ethylene in a living fashion. In contrast to the dimethyl complexes only [Ap(2)*ZrCl2] in the presence of MAO at elevated temperature gave decent polymerization activity. NMR investigations of the reaction of dichloro complexes with 25 equiv. of MAO or AlMe3 at room temperature revealed, that [Ap(2)ZrCl(2)] decomposes under ligand transfer to aluminum and formation of [ApAlMe(2)], while [Ap(2)*ZrCl2] remains almost unreacted under the same conditions. The aminopyridinato dimethyl aluminum complexes, [ApAlMe(2)] (5a) and [Ap*AlMe2] (5b) were synthesized independently and structurally characterized. The aluminum complexes 5a and b show no catalytic activity towards ethylene, when "activated" with[R2N(Me)H][B(C6F5)(4)]. (C) 2007 Elsevier B.V. All rights reserved.

We present in this account the synthesis and recent developments of a new class of group 4 metal complexes with the tridentate di(silylamido)cyclopentadienyl ligand. These doubly silyl-bridged group 4 metal amido chelates are receiving increasing interest as they are efficient catalysts for ethene polymerization when activated with MAO despite generating 14-electron d0 cationic species free of the alkyl group required for the first insertion reaction in the polymerization process., Programa Juan de la Cierva (Ministerio de Educación y Ciencia)

The thiolato-bridged binuclear molybdenum complexes [Mo 2 Cp 2 L 2 (μ-SMe) 2 (μ-L′)]Y (Cp = η 5 -C 5 H 5 ; L′ = SMe, L = Bu t NC ( 1a ), xylNC ( 1b ) or CO ( 3 ); L′ = PPh 2 , L = Bu t NC ( 16 ); Y = BF 4 , Cl) react with the anionic reagents NaBH 4 , NaBD 4 , LiR (R = Me, Bu n ), R′MgCl (R′ = Me, Pr i , Bu n or Ph). The products are unsubstituted ( 5 , 7 ) or substituted ( 8 – 12 ) η 4 -cyclopentadiene derivatives, [Mo 2 (η 5 -C 5 H 5 )(η 4 -C 5 H 5 R)L 2 (μ-SMe) 3 ] (L = xylNC, CO), or μ-formimidoyl dinuclear products, [Mo 2 Cp 2 L 2 (μ-SMe) 2 (μ-L′)(μ-CHNR)] (L′ = SMe, L = Bu t NC ( 4 ) or xylNC ( 6 ); L′ = PPh 2 , L = Bu t NC ( 17 )). Since the reduced dinuclear species [Mo 2 Cp 2 (CO) 2 (μ-SMe) 2 ] and the related oxo-compound [Mo 2 Cp 2 (CO)(O)(μ-SMe) 2 ] are sometimes isolated as minor products, the anionic reagent can play a secondary role as a reductant in these reactions in addition to its main role as a nucleophile. The electronic properties of the donor carbon atoms of the cyclopentadienyl rings and of the terminal ligands L, together with the nature of the anionic reagent, are the dominant factors controlling selective formation of 4 – 12 and 17 . Tetrafluoroboric acid reacts with the substituted cyclopentadiene derivatives 9 , 11 and 12 to form new functionalised cyclopentadienyl derivatives, [Mo 2 (η 5 -C 5 H 5 )(η 5 -C 5 H 4 R)(CO) 2 (μ-SMe) 3 ](BF 4 ) (R = Me ( 13) , Bu n ( 14 ) or Ph ( 15 )). New complexes have been characterised by spectroscopic and chemical methods, supplemented for 5 , 6 and 12 by X-ray diffraction studies at 100 K.

Reaction of the disilylcyclopentadiene 1,1-[SiMe2(CH2CHdouble bond; length as m-dashCH2)]2C5H4 with NbCl5 gave the new allylsilyl-substituted monocyclopentadienyl niobium complex [Nb{η5-C5H4SiMe2(CH2CHdouble bond; length as m-dashCH2)}Cl4]. This compound was reacted with LiNHtBu or NH2tBu to give the imido derivative [Nb{η5-C5H4SiMe2(CH2CHdouble bond; length as m-dashCH2)}(NtBu)Cl2], which was further alkylated to the imido alkyl complexes [Nb{η5-C5H4SiMe2(CH2CHdouble bond; length as m-dashCH2)}(NtBu)R2] (R = Me, CH2Ph) and [Nb{η5-C5H4SiMe2(CH2CHdouble bond; length as m-dashCH2)}(NtBu)Cl (CH2Ph)]. Reaction of the imido complexes with the corresponding lithium cyclopentadienides gave the dicyclopentadienyl-imido complexes [M(η5-C5R5){η5-C5H4SiMe2(CH2CHdouble bond; length as m-dashCH2)}(NtBu)Cl] (M = Nb, Ta; R = H, Me). Metallocene dichlorides [M(η5-C5R5){η5-C5H4SiMe2(CH2CHdouble bond; length as m-dashCH2)}Cl2] (M = Nb, Ta; R = H, Me) were easily prepared by reduction with Na/Hg and simultaneous transmetallation of [Ta(η5-C5R5)Cl4] with Li[C5H4SiMe2(CH2CHdouble bond; length as m-dashCH2)] and of [Nb{η5-C5H4SiMe2(CH2CHdouble bond; length as m-dashCH2)}Cl4] with Li(C5R5). All of the new compounds have been characterized by elemental analysis, and IR and NMR spectroscopy., Financial support of our work by MCyT (Project MAT2001-1309) is gratefully acknowledged.

The trisubstituted methyl-phenyl-silyl-cyclopentadienes [Me-Ph-C5H3(SiMe2X)] (X = Me, Cl, NHt-Bu) and [(Me-Ph-C5H3)2SiMe2] and the lithium salts Li2[Me-Ph-C5H2(SiMe2Nt-Bu)] and Li2[(Me-Ph-C5H2)2SiMe2] have been isolated by conventional methods and characterized by NMR spectroscopy. Desilylation of [Me-Ph-C5H3(SiMe3)] with ZrCl4(SMe2)2 gave the monocyclopentadienyl complex [Zr(η5-1-Ph-3-Me-C5H3)Cl3]. The ansa-metallocene [Zr{(η5-2-Me-4-Ph-C5H2)SiMe2(η5-2-Ph-4-Me-C5H2)}Cl2] was obtained from the mixture of isomers formed by transmetallation of Li2[(Me-Ph-C5H2)2SiMe2] to ZrCl4 and characterized as the meso-diastereomer by X-ray diffraction methods. Similar transmetallation of Li2[Me-Ph-C5H2(SiMe2Nt-Bu)] gave the silyl-η-amido complex [Zr{η5-2-Me-4-Ph-C5H2(SiMe2-η-Nt-Bu)}Cl2] that was further alkylated to give [Zr{η5-2-Me-4-Ph-C5H2(SiMe2-η-Nt-Bu)}R2] (R = Me, CH2Ph) and used as a catalyst precursor, activated with MAO, for ethene and propene polymerization. All of the new compounds were characterized by elemental analysis and NMR spectroscopy., Ministerio de Educación, Cultura y Deporte

New complexes of the type [Fe(η5-Cp or Ind)(L)(L′)(p-NCR)][BF4] (L, L′=CO, P(OC6H5)3, P(C6H5)3; R=C6H4N(CH3)2, C6H4NO2, (E)-C(H)C(H)C6H4NO2, (E)-C(H)C(H)C6H4N(CH3)2) have been synthesised and characterised. Spectroscopic data were analysed in order to evaluate the tuning of the electronic density at the metal centre and the extension of the π-delocalisation on the molecule, due to the presence of coligands with different acceptor/donor abilities. The structures of two complexes [Fe(η5-C5H5)(CO)(P(OC6H5)3)(p-NCC6H4NO2)][BF4] and [Fe(η5-C9H7)(CO)(P(OC6H5)3)(p-NCC6H4NO2)][BF4] were determined by X-ray crystallographic analysis. The compounds crystallised in the centrosymmetric space groups P1 and P21/n, respectively. Bond distances within the nitrile ligand are discussed in order to evaluate the nature of iron–nitrile bonding in these complexes.

International audience; The synthesis, reactivity, structures and electrochemistry of dimolybdenum complexes jointly stabilized by cyclopentadienyl and bridging thiolate ligands are reviewed. The complexes involved are principally those of molybdenum(II) and molybdenum(III) and they contain from one to four thiolate bridges. It is shown that their reactivity can be controlled by varying the electronic and steric properties of the ancillary ligands and that they provide bimetallic sites for the activation and transformation of various substrates. © 1998 Elsevier Science S.A. All rights reserved.

The 2-cyclopentadienyl-2-fluorenylpropane ligand has been converted into the monometalated derivatives M[CMe2(C5H4)(C13H9)] (MLi, Tl,) and CMe2[C5H4(SiMe3)](C13H9). These alkylating reagents have been characterized, and used to synthesize a new series of organotitanium (IV) complexes. The trimethylsilyl derivative was treated with TiCl4 to give the monocyclopentadienyl compound [Ti{CMe2(h 5 -C5H4)(C13H9)}Cl3]. Reaction of the thallium derivative with [Ti(h 5 -C5R5)Cl3] afforded the ‘mixed-ring’ dicyclopentadienyl complexes [Ti{CMe2(h 5 -C5H4)(C13H9)}(h 5 -C5R5)Cl2 ]( R H, Me), whereas the reaction of TiCl4 with two equivalents of the lithium compound led to the dicyclopentadienyl complex [Ti{CMe2(h 5 C5H4)(C13H9)}2Cl2]. The monocyclopentadienyl compound [Ti{CMe2(h 5 -C5H4)(C13H9)}Cl3] was readily hydrolyzed to give [Ti{CMe2(h 5 -C5H4)(C13H9)}Cl2]2(m-O) in wet acetone (0.5% H2O). The dicyclopentadienyl derivative [Ti{CMe2(h 5 C5H4)(C13H9)}(h 5 -C5Me5)Cl2] was further converted into [Ti{CMe2(h 5 -C5H4)(C13H9)}(h 5 -C5Me5)Me2] by alkylation with LiMe. Structural data of the titanium complexes demonstrate the h 5 -coordination of the cyclopentadienyl ring of the ancillary ligand, whereas the fluorenyl ring is not coordinated to the metal center. This mode of coordination is confirmed by the X-ray crystal structure analysis of [Ti{CMe2(h 5 -C5H4)(C13H9)}2Cl2]. © 1998 Elsevier Science S.A. All rights reserved.

Reactions of the tricarbonyl-molybdenum and -tungsten complexes [M(CO)3(MeCN)3] (M = Mo, W or [Mo(CO)3(mesitylene)] with equimolar amounts of [Ti(η5-Cp′){(η5-C5H3)(SiMe2)2 (C5H4)}Cl2] (Cp′ = C5H5, C5Me5) lead to the heterodinuclear compounds [Ti(η5-Cp′)Cl2{μ-[(SiMe2)2(η5-C5H3)2]}MH(CO)3]. These dinuclear complexes are isolated as single cis- and trans-isomers or as mixtures of both depending on the starting complex and the reaction conditions. The molar ratio of the two resulting isomers is controlled by thermodynamic and kinetic factors which prevent the application of stereoselective methods for some of the products. Reaction of the hydrido cis- and trans-complexes with CCl4 in CH2Cl2 allows the isolation of chloro complexes [Ti(η5-Cp′)Cl2{μ-[(SiMe2)2(η5-C5H3)2]} MCl(CO)3] of the same configuration. All of the new heterodinuclear compounds reported were characterized by their analytical composition, IR and NMR spectroscopy and the molecular structure of cis-[Ti(η5-C5Me5)Cl2{μ-[(SiMe2)2(η5-C5H3)2]}WH(CO)3] was studied by X-ray diffraction methods., Comunidad Autónoma de Madrid

International audience; The thermal reaction of [Mo2Cp2(μ-SMe)3(μ-Cl)] 1 with NaN3 in THF/EtOH gives a mixture of three compounds [Mo2Cp2(μ-SMe)3(μ-N3)] 2, [Mo2Cp2(μ-SMe)3(μ-NH2)] 3 and [Mo3(O)(N)Cp3(SMe)4] 4. Only the μ-azido derivative 2 is isolated if the time of thermolysis is short. Its formation in the presence of EtOH leads in turn to the products 3 and 4. Production of 3 from 2 requires N2 loss followed by intermolecular reduction of the bimetallic system. Complete decomposition of the complexes occurs if the time of reaction is prolonged. An X-ray diffraction study shows that 4 contains a [Mo2Cp2(μ-SMe)3(μ-N)] core that is linked through a Mo=N double bond to a CpMo(O)(SMe) unit. The resulting Mo3(μ3-N) fragment, in which the N=Mo double bond is supported by two Mo-N single bonds involving the directly bonded metal atoms, is the most striking structural feature of 4. The triply-bridging nitrido nitrogen atom adopts a distorted trigonal planar coordination.

International audience; The mixed amide complexes [U(NE$t_2$$)_2$(N{Si$Me_3$$\}_2$$)_2$] and [U($\eta$-$C_{8}$$H_{8}$)(NE$t_{2}$)(N{Si$Me_{3}$$\}_{2}$)] reacted in tetrahydrofuran (THF) with NE$t_{3}$HB$Ph_{4}$ to give the cations [U(NE$t_{2}$)(N{Si$Me_{3}$$\}_{2}$$)_{2}$(THF$)_{x}$$]^{+}$ and [U($\eta$-$C_{8}$$H_{8}$)(N{$Me_{3}$$\}_{2}$$)_{2}$(THF$)_{x}$$]^{+}$. The bis(trimethylsilyl) amide complex [U($\eta$-$C_{5}$$Me_{5}$$)_{2}$ (N{Si$Me_{3}$$\}_{2}$)] was inert towards NE$t_{3}$H B$Ph_{4}$ but its treatment with N$H_{4}$B$Ph_{4}$ afforded the cationic uranium(III) compound [U(($\eta$-$C_{5}$$Me_{5}$$)_{2}$ (THF$)_{2}$][B$Ph_{4}$], the crystal structure of which has been determined.

International audience; The thermal reaction of [C5H5Mo(CO)3H] with dimethyl disulfide and allyl chloride has been reinvestigated. In addition to the expected cationic species [(C5H5)2Mo2(μ-SMe)3(CO)2]Cl (1), the new trinuclear complex [(C5H5)Mo(CO)(μ-SMe)3Mo(CO)2(μ- SMe)Mo(CO)2(C5H5)] (2) was obtained. An X-ray diffraction study showed that 2 contains a (C5H5)(CO)Mo(μ-SMe)3Mo(CO)2 core in which the triply bridged Mo-Mo bond is of normal length (2.800(1) Å). This core is linked to the C5H5Mo(CO)2SMe unit via its sulfur atom and through an unusually weak Mo-Mo bond of 3.115(2) Å, the Mo-Mo-Mo angle being 144.5(1)°.

1-(Dimethylaminoethyl)-2,3,4,5-tetramethylcyclopentadienyl(chloro)germylene (1) is prepared from GeCl2 · dioxane and 1-(dimethylaminoethyl)-2,3,4,5-cyclopentadienyllithium. In 1 the nitrogen atom of the side chain is coordinated to the Ge(II) center. As a consequence of N coordination, the GeCl bond is one of the longest ever found, and the GeCp interaction is in between π and σ bonding.

The compounds [Zr(η-C5H5){CPh(NSiMe3)2}2Cl], [{Zr(η-C5H5)[CPh(NSiMe3)2]Cl}2{μ-CPh(NSiMe3)2}] [{Zr(η-C5H5)[CPh(NSiMe3)2]Cl}2(μ-O)], [Zr(η-C5R5){CPh(NSiMe3)2}(CH2Ph)Cl] (R = H or Me), [Zr(η-C5R5){CPh(NSiMe3)2}(CH2Ph)2] (R = H or Me) and [M(η-C5R5){CPh(NSiMe3)2}Me2] (M = Zr, R = H or Me; M = Ti, R = H have been synthesized and the crystal structures of three of them) determined.

Peralkylierte Cyclopentadien-Systeme des Typs Me5C5(CH2)3Si(Me)mY3-m, die über eine Alkyliden-Spacergruppe mit einer funktionalisierten Silan-Einheit verknüpft sind, sind auf zwei verschiedenen Wegen synthetisiert worden. Als Beispiel für den ersten Weg wird die Synthese des Disiloxans [Me5C5CH2)3Si(Me)2]2O (2) beschrieben, welches ausgehend von der Iodverbindung [I(CH2)3Si(Me)2]2O (1) durch Umsetzung mit Me5C5K dargestellt werden kann. Das Trichlorsilan Me5C5(CH2)3SiCl3 (4), als Synthesebeispiel für den zweiten Weg, ist über Hydrosilylierung von 1-Prop-2-enyl-1,2,3,4,5-pentamethylcyclopenta-2,4-dien (3) zugänglich. Beide Synthesewege sind auch zur Darstellung der teilweise alkylierten Cyclopentadiensysteme des Typs Me4HC5(CH2)3Si(Me)mY3-m geeignet. So führen die Umsetzungen der [omega]-Iodalkyl-triethoxysilane I(CH2)nSi(OEt)3 (n = 1, 2, 3) mit Me4HC5K zu den entsprechenden [omega]-(Tetramethylcyclopentadienyl)alkyl-triethoxysilanen 5–7. Verbindungen 5–7 liegen als Isomerengemische vor; das Verhältnis zwischen den Isomeren, die ein allylständiges oder ein vinylständiges Wasserstoffatom am Cyclopentadienring aufweisen, ist abhängig von der Spacerlänge. Isomerengemische der 4-(Tetramethylcyclopentadienyl)butyl-silane des Typs Me4HC5(CH2)4Si(Me)mCl3-m (m = 1, 2, 3) (8–10) mit ausschließlich allyiständigem Wasserstoffatom am Cyclopentadienring können durch Hydrositylierung von 1-But-3-enyl-2,3,4,5-tetramethyleyclopentadien dargestellt werden. Die am Siliciumatom funktionalisierten Verbindungen 2 und 4–10 können weiter derivatisiert werden. An ausgewählten Beispielen wird die Hydrolyse, die Alkoholyse, die reduktive Kupplung, die Heterogenisierung und die Polykondensationsreaktion näher untersucht. So erhält man das Silanol 12 und das Disiloxan 13, die Alkoxysilane 14–17, das Disilan 18 und die funktionalisierten Kieselgele 19–20. Verbindungen 2, 4–10 und 12–20 dienen als “Pool” zur Darstellung von Übergangsmetall-Derivaten. Beispielsweise wird die Dicarbonyl—Cobalt-Verbindung 21 durch Umsetzung von 8 mit Co2(CO)8 gebildet. Reaktion von 16 mit K und FeCl2 liefert das Ferrocen-Derivat 22. Die [eta]4-gebundenen Pt(II)- und Pd(II)-Komplexe 23–27 können durch Umsetzung der funktionalisierten Si---O-Verbindungen 2, 13, und 19–20 mit [PtCl2(Ethylen)]2 oder PdCl2(PhCN)2 erhalten werden., Peralkylated cyclopentadiene systems of the type Me5C5(CH2)3Si(Me)mY3-m, which possess cyclopentadiene units connected with a functionalized silane fragment by an alkylidene spacer group, are prepared via two routes. As an example of the first route, the disiloxane [Me5C5(CH2)3Si(Me)2]2O (2) has been synthesized from the corresponding iodo compound [I(CH2)3Si(Me)2]2O (1) by reaction with Me5C5K. The trichlorosilane Me5C5(CH2)3SiCl3 (4), as an example of a compound prepared via the second route, has been isolated after hydrosilylation of 1-prop-2-enyl-1,2,3,4,5-pentamethylcyclopenta-2,4-diene (3) with HSiCl3. Both synthetic methods are also suitable for the preparation of partly alkylated cyclopentadiene systems of the type Me4HC5(CH2)nSi(Me)mY3-m. Thus the omega-iodoalkyltriethoxysilanes I(CH2)nSi(OEt)3 (n = 1, 2, 3) react with Me4HC5K to give the corresponding omega-(tetramethyl-cyclopentadienyl)alkyl-triethoxysilanes 5-7. Compounds 5-7 consist of a mixture of isomers; the ratio between isomers having an allylic or vinylic hydrogen atom at the cyclopentadiene ring depends on the spacer length. Isomeric mixtures of the 4-(tetramethyl-cyclopentadienyl)butyl-silanes of the type Me4HC5(CH2)4Si(Me)mCl3-m (M = 1, 2, 3) (8-10) with an allylic hydrogen atom at the cyclopentadiene ring have been prepared by hydrosilylation of 1-but-3-enyl-2,3,4,5-tetramethylcyclopentadiene. The silane fragment in the alkylated cyclopentadiene systems 2 and 4-10 can be modified further. As examples hydrolysis, alcoholysis, reductive coupling, heterogenisation and polycondensation reactions are described. Following theses procedures the corresponding silanol 12 and disiloxane 13 have been prepared as well as the alkoxysilanes 14-17, the disilane 18 and the functionalized silicagels 19 and 20. Compounds 2, 4-10 and 12-20 serve as a ''pool'' for the preparation of transition metal complexes. The dicarbonyl cobalt compound 21 has been synthesized by reaction of 8 with CO2(CO)8. Reaction of 16 with K and FeCl2 gives the corresponding ferrocene derivative 22. The eta4-bound Pt(II) and Pd(II)-complexes 23-27 have been prepared by reaction of the functionalized Si-O-compounds 2, 13, and 19-20 with [PtCl2(Ethylen)]2 and PdCl2(PhCN)2, respectively.

Treatment of [FeCp(CO)2Cl] with 1 equiv of the amidophosphine ligands Li[R2PNR′] (R = Ph, iPr, R′ = iPr, tBu, Cy) afforded complexes of the type [FeCp(CO)(κ2(C,P)-(CO)–NiPr-PPh2)] (1a), [FeCp(CO)(κ2(C,P)-(CO)-NtBu-PPh2)] (1b), and [FeCp(CO)(κ2(C,P)-(CO)-NCy-PiPr2)] (1c) in 40–50% yields. Complex 1a was also formed when [FeCp(CO)2(PPh2NHiPr)]+ (2) was reacted with 1 equiv of KOtBu. These complexes feature a four-membered carboxamido-phospha-ferracycle as a result of an intramolecular nucleophilic attack of the amidophosphine ligand on coordinated CO. Upon treatment of 1a with the electrophile [Me3O]BF4 the aminocarbene complex [FeCp(CO)(κ2(C,P)C(OMe)-NiPr-PPh2)]+ (3) was obtained bearing an aza-phospha-carbene moiety. Upon treatment of cis,trans,cis-[Fe(CO)2(Ph2PNHiPr)2(Br)2] (4a) and cis,trans,cis-[Fe(CO)2(Ph2PNHtBu)2(Br)2] (4b) with KOtBu the carboxamido-phospha-ferracycles trans-[Fe(CO)2(κ2(C,P)-(CO)-NiPr-PPh2)(Ph2PNHiPr)Br] (5a) and trans-[Fe(CO)2(κ2(C,P)-(CO)-NtBu-PPh2)(Ph2PNHtBu)Br] (5b) were formed in moderate yield. Finally, representative structures were determined by X-ray crystallography.

The redox chemistry of triruthenium metallacyclopentadienyl clusters Ru 3 (CO) 8 (RC 2 R) 2 has been investigated by electrochemical, spectroscopic, and theoretical techniques and compared with that of homologous triiron derivatives. The sequence of the electrode processes has been postulated on the basis of the responses of different electrochemical techniques, electron spin resonance (ESR) spectroscopy, and chemical tests. The linear correlations between the formal electrode potentials of these derivatives and the wavenumbers of the visible bands of their electronic spectra have been discussed on the basis of Fenske-Hall quantum mechanical approach carried out on the model compounds M 3 (CO) 8 (HC 2 H) 2 (M=Fe,Ru) in the idealized C 2v geometry

RhCl3 is shown to mediate unusual coupling reactions of tert-butyl acetylene. When RhCl3(H2O)n was heated with four equivalents of tert-butyl acetylene in methanol, the dinuclear complex [{Rh(μ-Cl)(CH2tBu)(tBuC=CHCOCH2tBu)}2] (2) was isolated. A larger excess of tert-butyl acetylene (12 equiv.) resulted in the formation of the dimer [{η5-C5H2tBu2(CH2tBu)}Rh(μ-Cl)3Rh(C24H42O2)] (3). Both complexes were analyzed by single-crystal X-ray diffraction.