Models of surface-confined metallocene derivatives

The silsesquioxane [((C₆H₁₁)₇Si₇O₉)(OH)₃] (LH₃) was reacted with [M(C₅H₅)₂Cl₂] (M = Ti, Zr, Hf) and with [Ti(C₅H₅)Cl₃]. The reaction with [Ti(C₅H₅)Cl₃] produced [Ti(C₅H₅)L], whereas the reaction with [Ti(C₅H₅)₂Cl₂] produced a mixture of [Ti(C₅H₅)L]_n. (n = 1, 2) as determined by NMR spectroscopy. Only [Ti(C₅H₅)L] could be isolated from the mixture. The reaction with [M(C₅H₅)₂Cl₂] (M = Zr, Hf) produced oligomeric species which contained no cyclopentadienyl ligands and which were formulated as containing trimeric [M₃L₄Cl]⁻ anions on the basis of analytical and spectroscopic data.     

Spezielle Organoschwefel- und -selenverbindungen einiger Übergangsmetalle

Aluminum phenylselenolate and 1-naphthylselenolat react with TiCl₄, ZrCl₄, NbCl₅, TaCl₅, WCl₆ and CrCl₃ · 3THF giving compounds of types M(SeR)₄ (M = Ti, Zr, W; R = C₆H₅, C₁₀H₇) and M(SeR)₃ (M = Nb, Ta, Cr; R = C₆H₅, C₁₀H₇). By reaction of nickel(II), cobalt(II) and cobalt(III) acetylacetonates with thiophenol, selenophenol and 1-selenonaphthol polymeric compounds of composition Ni(XR)₂, Co(XR)_n (X = S, Se; R = C₆H₅, C₁₀H₇; n = 2 or 3) and Co(SC₆H₅)₂ · C₆H₅SH are obtained. [(n-C₄H₉)₃P]₂NiCl₂ and selenophenol in the presence of triethylamine give the monomeric compound [(n-C₄H₉)₃P]₂Ni(SeC₆H₅)₂.     

Préparation des complexes [(C5Me4H)2MX2] (M  Ti,Zr; X  Cl,alkyl, aryl,CO). Etude par RMN dynamique de la gêne stérique à la rotation des groupements aryle liés au métal

The new ligand C₅Me₄H reacts with [TiCl₃] or [ZrCl₄] to afford the dichlor complexes [(C₅Me₄H)₂MCl₂] (M  Ti, Zr) and the trichloro complex [(C₅Me₄H)-TiCl₃]. Treatment of these complexes with RLi, or their reduction under CO, gives the derivatives [(C₅Me₄H)₁)MR₂] (R  CH₃, C₆H₅, p-C₆H₄CH₃, CO). The preparation of the new series of compounds, [(C₅Me₄H)(C₅H₅)TiR₂], is also described. The electronic effects of the C₅Me₄H ligand resemble closely those of C₅Me₅. The coalescence of the ¹H and ¹³C NMR aromatic signals indicates that rotation of the aromatic nucleus around the metal-carbon bond is restricted owing to the large size of the C₅Me₄H ligand in the aryl complexes. The activation parameters of this rotation have been determined for [(C₅Me₄H)₂Ti(p-C₆H₄CH₃)₂].     

Monomer-Isomerization polymerization. XXVIII. Catalytic activity of transition metals and alkylaluminums in monomer-isomerization polymerization of 2-butene

Monomer-isomerization polymerization of cis-2-butene (c2B) with Ziegler–Natta catalysts was studied to find a highly active catalyst. Among the transition metals [TiCl₃, TiCl₄, VCl₃, VOCl₃, and V (acac)₃] and alkylauminums used, TiCl₃? R₃Al (R = C₂H₅ and i-C₄H₉) was found to show a high-activity for monomer-isomerization polymerization of c2B. The polymer yield was low with TiCl₄? (C₂H₅)₃Al catalyst. However, when NiCl₂ was added to this catalyst, the polymer yield increased. With TiCl₃? (C₂H₅)₃Al catalyst, the effect of the Al/Ti molar ratio was observed and a maximum for the polymer yields was obtained at molar ratios of 2.0–3.0, but the isomerization increased as a function of Al/Ti molar ratio. The valence state of titanium on active sites for isomerization and polymerization is discussed.     

Titanium and Zirconium Complexes with Non‐Salicylaldimine‐Type Imine–Phenoxy Chelate Ligands: Syntheses,Structures, and Ethylene‐Polymerization Behavior

New Ti and Zr complexes that bear imine–phenoxy chelate ligands, [{2,4‐di‐tBu‐6‐(RCH=N)‐C₆H₄O}₂MCl₂] ( 1 : M=Ti, R=Ph; 2 : M=Ti, R=C₆F₅; 3 : M=Zr, R=Ph; 4 : M=Zr, R=C₆F₅), were synthesized and investigated as precatalysts for ethylene polymerization. ¹H NMR spectroscopy suggests that these complexes exist as mixtures of structural isomers. X‐ray crystallographic analysis of the adduct 1 ?HCl reveals that it exists as a zwitterionic complex in which H and Cl are situated in close proximity to one of the imine nitrogen atoms and the central metal, respectively. The X‐ray molecular structure also indicates that one imine phenoxy group with the syn C?N configuration functions as a bidentate ligand, whereas the other, of the anti C?N form, acts as a monodentate phenoxy ligand. Although Zr complexes 3 and 4 with methylaluminoxane (MAO) or [Ph₃C]⁺[B(C₆F₅)₄]^?/AliBu₃ displayed moderate activity, the Ti congeners 1 and 2 , in association with an appropriate activator, catalyzed ethylene polymerization with high efficiency. Upon activation with MAO at 25 °C, 2 displayed a very high activity of 19900 (kg PE) (mol Ti)^?1 h^?1, which is comparable to that for [Cp₂TiCl₂] and [Cp₂ZrCl₂], although increasing the polymerization temperature did result in a marked decrease in activity. Complex 2 contains a C₆F₅ group on the imine nitrogen atom and mediated nonliving‐type polymerization, unlike the corresponding salicylaldimine‐type complex. Conversely, with [Ph₃C]⁺[B(C₆F₅)₄]^?/AliBu₃ activation, 1 exhibited enhanced activity as the temperature was increased (25–75 °C) and maintained very high activity for 60 min at 75 °C (18740 (kg PE) (mol Ti)^?1 h^?1). ¹H NMR spectroscopic studies of the reaction suggest that this thermally robust catalyst system generates an amine–phenoxy complex as the catalytically active species. The combinations 1 /[Ph₃C]⁺[B(C₆F₅)₄]^?/AliBu₃ and 2 /MAO also worked as high‐activity catalysts for the copolymerization of ethylene and propylene.     

Homoleptic alkenyls of the early transition metals and related compounds

The first stable homoleptic alkenyls of the early transition metals, MR_n, (R = C(Ph)=CMe₂; M = Ti, Zr, Hf, n = 4; and M = Cr, n = 3) and the related species (C₅H₅)₂MR₂ (M = Ti, Zr) and (C₅H₅)₂Zr(Cl)R have been prepared using appropriate organolithium reagents. Cleavage and insertion reactions are reported for the new compounds.     

Olefin polymerization and copolymerization by complexes bearing [ONNO]‐Type salan ligands: Effect of ligand structure and metal type (titanium,zirconium, and vanadium)

A series of novel titanium(IV) complexes bearing tetradentate [ONNO] salan type ligands: [Ti{2,2′‐(OC₆H₃‐5‐t‐Bu)₂‐NHRNH}Cl₂] (Lig¹TiCl₂: R = C₂H₄; Lig²TiCl₂: R = C₄H₈; Lig³TiCl₂: R = C₆H₁₂) and [Ti{2,2′‐(OC₆H₂‐3,5‐di‐t‐Bu)₂‐NHC₆H₁₂NH}Cl₂] (Lig⁴TiCl₂) were synthesized and used in the (co)polymerization of olefins. Vanadium and zirconium complexes: [ M{2,2′‐(OC₆H₃‐3,5‐di‐t‐Bu)₂‐NHC₆H₁₂NH}Cl₂] (Lig⁴VCl₂: M = V; Lig⁴ZrCl₂: M = Zr) were also synthesized for comparative investigations. All the complexes turned out active in 1‐octene polymerization after activation by MAO and/or Al(i‐Bu)₃/[Ph₃C][B(C₆F₅)₄]. The catalytic performance of titanium complexes was strictly dependent on their structures and it improves for the increasing length of the aliphatic linkage between nitrogen atoms (Lig¹TiCl₂ << Lig²TiCl₂ < Lig³TiCl₂) and declines after adding additional tert‐Bu group on the aromatic rings (Lig³TiCl₂ < Lig⁴TiCl₂). The activity of all titanium complexes in ethylene polymerization was moderate and the properties of polyethylene was dependent on the ligand structure, cocatalyst type, and reaction conditions. The Et₂AlCl‐activated complexes gave polymers with lover molecular weights and bimodal distribution, whereas ultra‐high molecular weight PE (up to 3588 kg mol^?1) and narrow MWD was formed for MAO as a cocatalyst. Vanadium complex yielded PE with the highest productivity (1925.3 kg mol_v^?1), with high molecular weight (1986 kg mol^?1) and with very narrow molecular weight distribution (1.5). Copolymerization tests showed that titanium complexes yielded ethylene/1‐octene copolymers, whereas vanadium catalysts produced product mixtures. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 2111–2123     

Synthesis,structure and ethylene polymerization of group 4 complexes with phosphinoamide ligands

Group 4 complexes containing diphosphinoamide ligands [Ph₂PNR]₂MCl₂ (3: R = ^tBu, M = Ti; 4: R = ^tBu, M = Zr; 5: R = Ph, M = Ti; 6: R = Ph, M = Zr) were prepared by the reaction of MCl₄ (M = Ti; Zr) with the corresponding lithium phosphinoamides in ether or THF. The structure of [Ph₂PN^tBu]₂TiCl₂ (3) was determined by X‐ray crystallography. The phosphinoamides functioned as η²‐coordination ligands in the solid state and the Ti? N bond length suggests it is a simple single bond. In the presence of modified methylaluminoxane or i‐Bu₃Al/Ph₃BC(C₆F₅)₄, catalytic activity of up to 59.5 kg PE/mol cat h bar was observed. Copyright © 2005 John Wiley & Sons, Ltd.     

A cyclopentadienyl ring exchange method for the attachment of early transition metal metallocene dichlorides to a polymer support

PMR and mass spectral analysis have been used to study the interchange of π-bonded cyclopentadienyl rings with σ-bonded cyclopentadienyl rings in the compounds (C₅H₅)₄M (M = Ti, Zr, Hf, Nb, Ta, Mo and W) and (C₅H₅)₃V or a-bonded benzylcyclopentadienyl rings in the compounds (C₆H₅CH₂C₅H₄) (C₅H₅)₂MC1 (M = Ti, Zr, Hf, Nb, Ta, Mo and W). As soon as the Cp₄M species are generated (indicated by a color change), the interchange occurs and the equilibrium is established. As reported, no such interchange was observed in (C₅H₅) ₄Mo in the PMR time scale; however, it does occur after a longer time. By using this interchange behavior of the cyclopentadienyl ring, metallocene dichlorides of Ti, Zr, Hf, V, Nb, Ta, Mo and W have been attached to polystyrene-divinylbenzene beads.     

Remote Multiproton Storage within a Pyrrolide‐Pincer‐Type Ligand

A chemically non‐innocent pyrrole‐based trianionic (ONO)^3? pincer ligand within [(pyr‐ONO)TiCl(thf)₂] ( 2 ) can access the dianionic [(3H‐pyr‐ONO)TiCl₂(thf)] ( 1‐THF ) and monoanionic [(3H,4H‐pyr‐ONO)TiCl₂(OEt₂)][B{3,5‐(CF₃)₂C₆H₃}₄] ( 3‐Et₂O ) states through remote protonation of the pyrrole γ‐C π‐bonds. The homoleptic [(3H‐pyr‐ONO)₂Zr] ( 4 ) was synthesized and characterized by X‐ray diffraction and NMR spectroscopy in solution. The protonation of 4 by [H(OEt₂)₂][B{C₆H₃(CF₃)₂}₄] yields [(3H,4H‐pyr‐ONO)(3H‐pyr‐ONO)Zr][B{3,5‐(CF₃)₂C₆H₃}₄] ( 5 ), thus demonstrating the storage of three protons.     

Synthesis and Reactivity of Boron‐, Silicon‐, and Tin‐Bridged ansa‐Cyclopentadienyl–Cycloheptatrienyl Titanium Complexes (Troticenophanes)

A novel one‐pot method was developed for the preparation of [Ti(η⁵‐C₅H₅)(η⁷‐C₇H₇)] (troticene, 1 ) by reaction of sodium cyclopentadienide (NaCp) with [TiCl₄(thf)₂], followed by reduction of the intermediate [(η⁵‐C₅H₅)₂TiCl₂] with magnesium in the presence of cycloheptatriene (C₇H₈). The [n]troticenophanes 3 (n=1), 4 , 8 , 10 (n=2), and 11 (n=3) were synthesized by salt elimination reactions between dilithiated troticene, [Ti(η⁵‐C₅H₄Li)(η⁷‐C₇H₆Li)] ? pmdta ( 2 ) (pmdta=N,N′,N′,N′′,N′′‐pentamethyldiethylenetriamine), and the appropriate organoelement dichlorides Cl₂Sn(Mes)₂ (Mes=2,4,6‐trimethylphenyl), Cl₂Sn₂(tBu)₄, Cl₂B₂(NMe₂)₂, Cl₂Si₂Me₄, and (ClSiMe₂)₂CH₂, respectively. Their structural characterization was carried out by single‐crystal X‐ray diffraction and multinuclear NMR spectroscopy. The stanna[1]‐ and stanna[2]troticenophanes 3 and 4 represent the first heteroleptic sandwich complexes bearing Sn atoms in the ansa bridge. The reaction of 3 with [Pt(PEt₃)₃] resulted in regioselective insertion of the [Pt(PEt₃)₂] fragment into the Sn? C_ipso bond between the tin atom and the seven‐membered ring, which afforded the platinastanna[2]troticenophane 5 . Oxidative addition was also observed upon treatment of 4 with elemental sulfur or selenium, to produce the [3]troticenophanes [Ti(η⁵‐C₅H₄SntBu₂)(η⁷‐C₇H₆SntBu₂)E] ( 6 : E=S; 7 : E=Se). The B? B bond of the bora[2]troticenophane 8 was readily cleaved by reaction with [Pt(PEt₃)₃] to form the corresponding oxidative addition product [Ti(η⁵‐C₅H₄BNMe₂)(η⁷‐C₇H₆BNMe₂)Pt(PEt₃)₂] ( 9 ). The solid‐state structures of compounds 5 , 6 , and 9 were also determined by single‐crystal X‐ray diffraction.     

Bis(cyclopentadienyl)methan-verbrückte Zweikernkomplexe,V. Heteronukleare Co/Rh-, Co/Ir-, Rh/Ir- und Ti/Ir-Komplexe mit dem Bis(cyclopentadienyl)methan-Dianion als Brückenliganden

Bis(cyclopentadienyl)methane-bridged Dinuclear Complexes, V^[1]. – Heteronuclear Co/Rh-, Co/Ir-, Rh/Ir-, and Ti/Ir Complexes with the Bis(cyclopentadienyl)methane Dianion as Bridging Ligand^* The lithium and sodium salts of the [C₅H₅CH₂C₅H₄]^- anion, 1 and 2 , react with [Co(CO)₄I], [Rh(CO)₂Cl]₂, and [Ir(CO)₃Cl]n to give predominantly the mononuclear complexes [(C₅H₅-CH₂C₅H₄)M(CO)₂] ( 3, 5, 7 ) together with small amounts of the dinuclear compounds [CH₂(C₅H₄)₂][M(CO)₂]₂ ( 4, 6, 8 ). The ¹H- and ¹³C-NMR spectra of 3, 5 , and 7 prove that the CH₂C₅H₅ substituent is linked to the π-bonded ring in two isomeric forms. Metalation of 5 and 7 with nBuLi affords the lithiated derivatives 9 and 10 from which on reaction with [Co(CO)₄I], [Rh(CO)₂Cl]₂, and [C₅H₅TiCl₃] the heteronuclear complexes [CH₂(C₅H₄)₂][M(CO)₂][M′(CO)₂] ( 11–13 ) and [CH₂(C₅H₄)₂]-[Ir(CO)₂][C₅H₅TiCl₂] ( 17 ) are obtained. Photolysis of 11 and 12 leads almost quantitatively to the formation of the CO-bridged compounds [CH₂(C₅H₄)₂][M(CO)(μ-CO)M′(CO)] ( 14, 15 ). According to an X-ray crystal structure analysis the Co/Rh complex 14 is isostructural to [CH₂(C₅H₄)₂][Rh₂(CO)₂(μ-CO)] ( 16 ).     

Monomer-isomerization polymerization. XXIII.. Monomer-isomerization polymerization of 5-phenyl-2-pentene with ziegler–natta catalysts

5-Phenyl-2-pentene (5Ph2P) was found to undergo monomer-isomerization polymerization with TiCl₃–R₃Al (R = C₂H₅ or i-C₄H₉, Al/Ti > 2) catalysts to give a polymer consisting of exclusively 5-phenyl-1-pentene (5Ph1P) unit. The geometric and positional isomerizations of 5Ph2P to its terminal and other internal isomers were observed to occur during polymerization. The catalyst activity of alkylaluminum examined to TiCl₃ was in the following order: (C₂H₅)₃Al > (i-C₄H₉)₃Al > (C₂H₅)₂AlCl. The rate of monomer-isomerization polymerization of 5Ph2P with TiCl₃–(C₂H₅)₃Al catalyst was influenced by both the Al/Ti molar ratio and the addition of nickel acetylacetonate [Ni(acac)₂], and the maximum rate was observed at Al/Ti = 2.0 and Ni/Ti = 0.4 in molar ratios.     

Silica-supported cyclopentadienyl-rhodium(I), -cobalt(I), and -titanium(IV) complexes

The silylated cyclopentadiene derivative, (MeO)₃Si(CH₂)₃C₅H₅, synthesised from commerically-available (MeO)₃Si(CH₂)₃Cl, has been used to prepare the complexes [η⁵-(MeO)₃Si(CH₂)₃C₅H₄]Rh(CO)₂, [η⁵-(MeO)₃Si(CH₂)₃C₅H₄]Rh(COD) (COD = cyclo-octa-1,5-diene), and [η⁵-(MeO)₃Si(CH₂)₃C₅H₄]₂TiCl₂. The complex [η⁵-(MeO)₃Si(CH₂)₃C₅H₄]TiCl₃, prepared by reaction of NaC₅H₄(CH₂)₃Si(OMe)₃ with TiCl₄ (1/1 molar ratio) and also by reaction of [η⁵-(MeO)₃Si(CH₂)₃C₅H₄]Ti(OEt)₃ with CH₃COCl, proved to be very unstable. Attempts to synthesise the complex [η⁵-(MeO)₃Si(CH₂)₃C₅H₄](η⁵-C₅H₅)TiCl₂, either by reaction of [η⁵-(MeO)₃Si(CH₂)₃C₅H₄]TiCl₃ with NaC₅H₄ or reaction of (η⁵-C₅H₅)TiCl₃ with NaC₅H₄(CH₂)₃Si(OMe)₃, gave none of the expected product and only (η⁵-C₅H₅)₂TiCl₂ could be isolated from these reactions. The cyclo-octadiene rhodium complex supported on silica has been shown to be an efficient cyclotrimerization catalyst, and the silica-supported titanium complex (SIL-(CH₂)₃C₅H₄)₂TiCl₂ is, after reduction with butyllithium, an efficient and selective catalyst for the hydrogenation of alk-1-enes.     

Preparation of dicyclopentadienylmetal-bis(trimethyl phosphite) complexes of titanium(II) and zirconium(II) by sodium atom reduction

The complexes (C₅H₅)₂M[P(OCH₃)₃]₂ (M = Ti and Zr) can be prepared by condensing sodium atoms at ?100°C into tetrahydrofuran solutions containing (C₅H₅)₂MCl₂ and excess trimethyl phosphite.     

Access a divers dichalcogenophenylenes metallocenes (M = Ti, Zr, Hf). Premier exemple d'un ditellurophenylene-zirconocene

Elementary sulfur and selenium combine (in boiling heptane) with [(tBuCp)₂-Zr(C₆H₄R)₂] (Cp = η⁵-C₅H₄; R = OCH₃) to give the corresponding dichalcogenophenylenezirconocene. With tellurium, the reaction proceeds only at lower temperature (in boiling hexane), affording the first ditellurophenylenezirconocene. As no metallacycle was obtained with the Cp ligand or when the metal is Hf, complexes of the general type [(RCp)₂MSe₂C₆H₄-o] (M = Ti, Zr, Hf; R = H, t-Bu, (CH₃)₅) have been synthesized by allowing metallocene dichlorides to react with potassium benzenediselenolate, prepared by cleaving [(t-BuCp)₂ZrSe₂C₆H₄-o] with t-BuOK.     

Mono(η5-cyclopentadienyl)-titan(IV)- und -zirconium(IV)-komplexe mit einem oder zwei toluol-3,4-dithiolat-liganden

The new toluene-3,4-dithiolate chelates CpMCl(S₂C₆H₃CH₃-4) (Cp = η⁵-C₅H₅; M = Ti (III), Zr (IV)) can be prepared by the reactions of CpTiCl₃ (I) or CpZrCl₃ (II) with equimolar amounts of (LiS)₂C₆H₃CH₃-4. I and II react with an excess of (LiS)₂C₆H₃CH₃-4, via III and IV, to give the fivefold-coordinated anions which can be isolated as the tetraethylammonium salts NEt₄[CpM(S₂C₆H₃CH₃-4)₂] (M = Ti (V), Zr (VI). ¹H NMR studies of III and V under variable temperatures indicate in both complexes the presence of only one sterically-promoted conformation of the five-membered TiS₂C₂ chelate rings.     

Heterobimetallische phosphanido-verbrückte Zweikern-Komplexe - Synthese von cis-rac-[(η-C5H4R)2Zr{μ-PH(2,4,6−iPr3C6H2)}2M(CO)4] (RMe,MCr,Mo; RH,MMo)

Heterobimetallic Phosphanido-bridged Dinuclear Complexes - Syntheses of cis-rac-[(η-C₅H₄R)₂Zr{μ-PH(2,4,6-ⁱPr₃C₆H₂)}₂M(CO)₄] (R?Me, M?Cr, Mo; R?H, M?Mo) The zirconocene bisphosphanido complexes [(η-C₅H₄R)₂Zr{PH(2,4,6-ⁱPr₃C₆H₂)}₂] (R?Me, H) react with [(NBD)M(CO)₄] (NBD?norbornadiene, M?Cr, Mo) to give only one diastereomer of the phosphanido-bridged heterobimetallic dinuclear complexes cis-rac-[(η-C₅H₄R)₂Zr{μ-PH(2,4,6-ⁱPr₃C₆H₂)}₂M(CO)₄] [R?Me, M?Cr ( 1 ), Mo ( 2 ); R?H, M?Mo ( 3 )]. However, no reaction was observed between [(η-C₅H₅)₂Zr{PH(2,4,6-^tBu₃ C₆H₂)}₂] and [Pt(PPh₃)₄]. 1—3 were characterised spectroscopically. For 1—3 , the presence of the racemic isomer was shown by NMR spectroscopy. No reaction was observed at room temperature for 3 and CS₂, (NO)BF₄, Me₃NO or PH(2,4,6-Me₃C₆H₂)₂. With Et₂AlH or PhC?CH decomposition of 3 was observed.     

Far IR and Raman spectra of some gaseous titanium,zirconium and hafnium cyclopentadienyl chlorides

The far IR and Raman spectra of gaseous (C₅H₅)TiCl₃ and (C₅H₅)₂MCl₂ species (M = Ti, Zr and Hf) are reported. The results are compared to the previous vibrational analysis of the corresponding species in the solid and matrix isolated phases. The assignment of the metal skeletal vibrations is reexamined in further detail on the basis of the new spectroscopic measurements. The torsional frequencies and the related potential barriers are investigated.