Synthesis and properties of poly‐1‐olefins

The oligomerization and polymerization of 1‐pentene using Cp₂ZrCl₂, Cp₂HfCl₂, [(CH₃)₅C₅]₂ZrCl₂, rac‐[C₂H₄(Ind)₂]ZrCl₂, [(CH₃)₂Si(Ind)₂]ZrCl₂, (CH₃)₂Si(2‐methylbenz[e]indenyl)₂ZrCl₂, Cp₂ZrCl{O(Me)CW(CO)₅}, Cp₂ZrCl(OMe) and methylaluminoxane (MAO) has been studied. The degree of polymerization was highly dependent on the metallocene catalyst. Oligomers ranging from the dimer of 1‐pentene to polymers of poly‐1‐pentene with a molar mass M_w = 149000 g/mol were formed. Cp₂ZrCl{O(Me)CW(CO)₅} is a new highly active catalyst for the oligomerization of 1‐pentene to low molecular weight products. The activity decreases in the order Cp₂ZrCl{O(Me)CW(CO)₅} > Cp₂ZrCl₂ > Cp₂ZrCl(OMe). Furthermore, poly‐1‐olefins ranging from poly‐1‐pentene to poly‐1‐octadecene were synthesized with (CH₃)₂Si(2‐methyl‐benz[e]indenyl)₂ZrCl₂ and methylaluminoxane (MAO) at different temperatures. The temperature dependence of the molar mass can be described by a common exponential decay function irrespective of the investigated monomer.     

Cyano Derivatives of Bis(cyclopentadienyl)titanium(IV). The crystal and molecular structure of μ-Oxo-bis[bis(cyclopentadienyl)cyanotitanium(IV)], [(η5-C5H5)2TiCN]2O

By the reaction of KCN with Cp₂TiCl₂ (Cp = η⁵-C₅H₅) in boiling methanol, bis(cyclopentadienyl)-methoxytitanium(IV) cyanide, Cp₂Ti(OCH₃)CN, is formed which in air is converted into the dinuclear oxygen-bridged derivative (Cp₂TiCN)₂O. By the same procedure, the bis(methylcyclopentadienyl) analogue [MeCp₂TiCN]₂O has been obtained. An X-ray diffraction study of (Cp₂TiCN)₂O has shown that the CN group acts as a unidentate ligand with a Ti? C bond length of 2.158 Å and a Ti? C? N bond angle of 177.7°, very close to linearity. The Ti? O bond distance, 1.836 Å, and the bond angle at the bridging O atom, 174.1°, are normal. The ligands are arranged in a nearly tetrahedral way around the Ti atoms. The structural results are compared to those for similar dinuclear titanium complexes.     

Four‐Membered Heterometallacyclic d0 and d1 Complexes of Group 4 Metallocenes with Amidato Ligands

A study of the coordination chemistry of different amidato ligands [(R)N?C(Ph)O] (R=Ph, 2,6‐diisopropylphenyl (Dipp)) at Group 4 metallocenes is presented. The heterometallacyclic complexes [Cp₂M(Cl){κ²‐N,O‐(R)N?C(Ph)O}] M=Zr, R=Dipp ( 1 a ), Ph ( 1 b ); M=Hf, R=Ph ( 2 )) were synthesized by reaction of [Cp₂MCl₂] with the corresponding deprotonated amides. Complex 1 a was also prepared by direct deprotonation of the amide with Schwartz reagent [Cp₂Zr(H)Cl]. Salt metathesis reaction of [Cp₂Zr(H)Cl] with deprotonated amide [(Dipp)N?C(Ph)O] gave the zirconocene hydrido complex [Cp₂M(H){κ²‐N,O‐(Dipp)N?C(Ph)O}] ( 3 ). Reaction of 1 a with Mg did not result in the desired Zr(III) complex but in formation of Mg complex [(py)₃Mg(Cl) {κ²‐N,O‐(Dipp)N?C(Ph)O}] ( 4 ; py=pyridine). The paramagnetic complexes [Cp′₂Ti{κ²‐N,O‐(R)N?C(Ph)O}] (Cp′=Cp, R=Ph ( 7 a ); Cp′=Cp, R=Dipp ( 7 b ); Cp′=Cp*, R=Ph ( 8 )) were prepared by the reaction of the known titanocene alkyne complexes [Cp₂′Ti(η²‐Me₃SiC₂SiMe₃)] (Cp′=Cp ( 5 ), Cp′=Cp* ( 6 )) with the corresponding amides. Complexes 1 a , 2 , 3 , 4 , 7 a , 7 b , and 8 were characterized by X‐ray crystallography. The structure and bonding of complexes 7 a and 8 were also characterized by EPR spectroscopy.     

Living ring‐opening polymerization of ϵ‐caprolactone with Ti alkoxides derived from the Cp2TiCl‐catalyzed SET reduction of aldehydes

A series of substituted benzaldehydes were investigated as initiators for the living ring‐opening polymerization (LROP) of ε‐caprolactone (CL) mediated by titanium alkoxides obtained from the Cp₂TiCl‐catalyzed single electron transfer (SET) reduction of the carbonyl group following the in situ reduction of Cp₂TiCl₂ with Zn. The aldehyde initiation was demonstrated (NMR) by the presence of the initiator derived fragment on the polycaprolactone (PCL) chain end. The effect of the nature of the aldehyde functionality (R‐Ph‐CHO, R = H, Cl, PhCH₂O, NMe₂, CH₃O, NO₂, and CHO), reagent ratios ([CL]/[aldehyde] = 50/1 to 400/1, [aldehyde]/[Cp₂TiCl₂] = 1/1 to 1/4, and [Cp₂TiCl₂]/[Zn] = 1/0.5 to 1/2), and temperature (T = 75–120 °C) was investigated over a wide range of values to reveal a living polymerization in all cases with an optimum observed at 90 °C with typical stoichiometric ratios of [CL]/[aldehyde]/[Cp₂TiCl₂]/[Zn] = 100/1/1/2. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 2869–2877, 2008     

Richtlinien und Bemerkungen der Redaktion und des Verlages für Abfassung von Manuskripten für die Zeitschrift für anorganische und allgemeine Chemie

Reaction of Trimethylsilylethers of Unsaturated Alcohols with Schwartz Reagent – Stabilisation of Cyclic Zirconiumorganic Compounds by the Moiety Cp₂ZrH₂ Besides the normal product of hydrozirconation the reaction of allyltrimethylsilylethers CH₂? CHC(R¹R²)OSi(CH₃)₃ ( I : R¹ = R² = H, VIII : R¹ = R² = CH₃, X : R¹ = H, R² = CH₃) with Cp₂Zr(H)Cl yields, as a result of a hydrogenation of the Si? O bond, trimethylsilane and a series of compounds with a Zr? O bond. Depending on the substitution of the α-C atom either dimeric chelates ( III ) or binuclear complexes of the type Cp₂Zr(Cl)CH₂CH₂C(R¹R²)OZr(Cl)Cp₂ ( IX : R¹ = R² = CH₃; XII : R¹ = H, R² = CH₃) are formed. Starting with X and excess Cp₂Zr(H)Cl the binuclear compound XIII is obtained which may be considered as an adduct of Cp₂ZrH₂ to the unsaturated chelate Compound XVII with a structure analogous to XIII is synthesized by the reaction of IX with Cp₂ZrH₂. The ¹H-NMR spectrum is in accordance with the existence of cis-trans-isomers of this complex.     

Molecular and crystal structures of adducts (Cp<Subscript>2</Subscript>YCl)<Subscript>2</Subscript>L (L = 2THF,DME, 1,4-dioxane)

The adducts [Cp₂Y(μ-Cl)]₂ · 2THF (5), {[Cp₂Y(μ-Cl)]₂ · 1,4-dioxane}_n (6), and Cp₂Y(DME)(μ-Cl)(Cl)YCp₂ (7) have been synthesized and studied by X-ray crystallography. In 5, the (Cp₂YCl)₂ moiety is coordinated to two THF molecules (d _(Y-O) = 2.478 Å); in 6 the (Cp₂YCl)₂ dimers are linked by 1,4-dioxane to form a polymer chain (d _(Y-O) = 2.601 Å). In asymmetric adduct 7, the DME molecule is bound through both O atoms to the same Y atom (d _(Y-O) = 2.382 and 2.448 Å), and one of the chlorine atoms is bridging and the other chlorine atom is terminal.     

Sur quelques réactions par décharge électrique dans les systèmes phosphine-eau,phosphine-eau-ammoniac et phosphine-eau-ammoniac-méthane

Electric discharge reactions in the systems PH₃ + H₂O, PH₃ + H₂O + NH₃ and PH₃ + H₂O + NH₃ + CH₄ have been studied. In the system PH₃ + H₂O, they produce polyphosphines (insoluble in water) and hypophosphorous, phosphorous and orthophosphoric acids. In the system PH₃ + H₂O + NH₃, besides the above products, hypophosphate, pyrophosphate, polyphosphates and possibly polyhyphosphates are also present. In the system PH₃ + H₂O + NH₃ + CH₄, besides all the above inorganic P compounds, organic phosphorus derivatives such as aminoalkyl phosphates and aminoalkanephosphonates are also formed, as well as other non-phosphorus containing organic products (amino acids, ethanolamine, etc.). The presence of phosphine (or its transformation products), seems to promote condensation reactions in this system since the ratio of amino acids found after hydrolysis (in 6N HCl) to amino acids found before hydrolysis is greater in this system. than in the system (CH₄+ H₂O+ NH₃)iiot containing phosphine.     

Cumulative subject index: vol. 176 (1979)–200 (1980)

Electron deficient CpTiCl₃ reacts with the bis-alkoxide CpCl$\text{TiOCMe}{}_2\text{CMe}{}_2\text{O}$ to produce the diolato dimer (CpTiCl₂)OCMe₂CMe₂O(TiCl₂Cp). CpTiCl₃ reacts with Cp₄Ti₄Cl₄(μ₂-O)₄, which also has two oxo ligands on each titanium atom, to produce [CpTiCl₂]₂O. These and other redistribution reactions indicate that destabilization results from internal competition for metal d-orbitals by strong π-donor (e.g. alkoxide) ligands. Equilibrium constants for the formation of the η²-acetyl complexes Cp₂Zr[C(O)Me]X by Co insertion into Cp₂ZrMeX decrease in the order X = Me>Cl>OEt. This reflects internal competition of π-donor orbitals on X with the oxygen donor orbital in the η²-acetyl functionally. The significance of this effect for Fischer-Tropsch syntheses in both homogeneouus and heterogeneous media is discussed.     

Sekundäre Hydroxyalkylphosphane: Synthese und Charakterisierung mono‐, bis‐ und trisalkoxyphosphan‐substituierter Zirconiumkomplexe und des heterobimetallischen Dreikernkomplexes [Cp2Zr{O(CH2)3PHMes(AuCl)}2]

Secondary Hydroxyalkylphosphanes: Synthesis and Characterization of Mono‐, Bis‐ and Trisalkoxyphosphane‐substituted Zirconium Complexes and the Heterobimetallic Trinuclear Complex [Cp₂Zr{O(CH₂)₃PHMes(AuCl)}₂] The secondary hydroxyalkylphosphanes RPHCH₂OH [R = 2,4,6‐Me₃C₆H₂ (Mes) ( 1 ), 2,4,6‐ⁱPr₃C₆H₂ (Tipp) ( 2 )], 1‐AdPH‐2‐OH‐cyclo‐C₆H₁₀ ( 3 ) and RPH(CH₂)₃OH [R = Ph ( 4 ), Mes ( 5 ), Tipp ( 6 ), Cy ( 7 ), ^tBu ( 8 )] were obtained from primary phosphanes RPH₂ and formaldehyde ( 1 , 2 ) or from LiPHR and cyclohexene oxide ( 3 ) or trimethylene oxide ( 4 ‐ 8 ). Starting from 5 or 7 and [Cp^R₂ZrMe₂] [Cp^R = C₅EtMe₄ (Cp°), C₅H₅ (Cp), C₅MeH₄ (Cp′)], the monoalkoxyphosphane‐substituted zirconocene complexes [Cp^R₂Zr(Me){O(CH₂)₃PHMes}] [Cp^R = Cp° ( 9 ), Cp ( 10 )] were prepared. With [Cp^R₂ZrCl₂], the bisalkoxyphosphane‐substituted complexes [Cp′₂Zr{O(CH₂)₃PHMes}₂] ( 11 ) and [Cp₂Zr{O(CH₂)₃PHCy}₂] ( 12 ) are obtained, and with [Tp^RZrCl₃], the trisalkoxyphosphane‐substituted zirconium complexes [Tp^RZr{O(CH₂)₃PHMes}₃] [Tp^R = trispyrazolylborato (Tp) ( 13 ), Tp^R = tris(3,5‐dimethyl)pyrazolylborato (Tp*) ( 14 )] are prepared. The reaction of 5 with [AuCl(tht)] (tht = tetrahydrothiophene) yielded the mononuclear complex [AuCl{PHMes(CH₂)₃OH}] ( 15 ). The trinuclear complex [Cp₂Zr{O(CH₂)₃PHMes(AuCl)}₂] ( 16 ) was obtained from [Cp₂ZrCl₂] and 15 . Compounds 1 ‐ 16 were characterized spectroscopically (¹H‐, ³¹P‐, ¹³C‐NMR; IR; MS) and compound 2 also by crystal structure determination. The bis‐ and trisalkoxyphosphane‐substituted complexes 11‐14 and 16 were obtained as mixtures of two diastereomers which could not be separated.     

A DFT Quantum‐Chemical Study of Ion‐Pair Formation for the Catalyst Cp2ZrMe2 /MAO

A process of ion‐pair formation in the system Cp₂ZrMe₂/methylaluminoxane (MAO) has been studied by means of density functional theory quantum‐chemical calculations for MAOs with different structures and reactive sites. An interaction of Cp₂ZrMe₂ with a MAO of the composition (AlMeO)₆ results in the formation of a stable molecular complex of the type Al₅Me₆O₅Al(Me)O–Zr(Me)Cp₂ with an equilibrium distance r(Zr–O) of 2.15 Å. The interaction of Cp₂ZrMe₂ with “true” MAO of the composition (Al₈Me₁₂O₆) proceeds with a tri‐coordinated aluminum atom in the active site (OAlMe₂) and yields the strongly polarized molecular complex or the μ‐Me‐bridged contact ion pair ( d ) [Cp₂(Me)Zr(μMe)Al≡MAO] with the distances r(Zr–μMe) = 2.38 Å and r(Al–μMe) = 2.28 Å. The following interaction of the μ‐Me contact ion pair ( d ) with AlMe₃ results in a formation of the trimethylaluminum (TMA)‐separated ion pair ( e ) [Cp₂Zr(μMe)₂AlMe₂]⁺–[MeMAO]^– with r[Zr–(MeMAO)] equal to 4.58 Å. The calculated composition and structure of ion pairs ( d ) and ( e ) are consistent with the ¹³C NMR data for the species detected in the Cp₂ZrMe₂/MAO system. An interaction of the TMA‐separated ion pair ( e ) with ethylene results in the substitution of AlMe₃ by C₂H₄ in a cationic part of the ion pair ( e ), and the following ethylene insertion into the Zr–Me bond. This reaction leads to formation of ion pair ( f ) of the composition [Cp₂ZrCH₂CH₂CH₃]⁺–[Me‐MAO]^– named as the propyl‐separated ion pair. Ion pair ( f ) exhibits distance r[Zr–(MeMAO)] = 3.88 Å and strong C_γ‐agostic interaction of the propyl group with the Zr atom. We suppose this propyl‐separated ion pair ( f ) to be an active center for olefin polymerization.     

Uranium-sulfilimine chemistry. The preparation of Cp2*UCl2(HNSPh2) and its hydrolysis with HNSPh2 · H2O

The reaction of Cp₂*UCl₂ with HNSPh₂ produces Cp₂*UCl₂(HNSPh₂), which is the first structurally characterized complex of a sulfilimine. The hydrolysis of Cp₂*UCl₂(HNSPh₂) with HNSPh₂ · H₂O yields a tetrauranium cluster whose heavy atom structure has been determined by x-ray diffraction and which is formulated as a U^IV/U^V complex: [Cp*(Cl)(HNSPh₂)U(μ₃-O)(μ₂-O)₂U(Cl)(HNSPh₂)₂]₂.     

Selective Functionalization of P4 by Metal‐Mediated CP Bond Formation

A new and selective one‐step synthesis was developed for the first activation stage of white phosphorus by organic radicals. The reactions of NaCp^R with P₄ in the presence of CuX or FeBr₃ leads to the clean formation of organic substituted P₄ butterfly compounds Cp^R₂P₄ (Cp^R: Cp^BIG=C₅(4‐nBuC₆H₄)₅ ( 1 a ), Cp′′′=C₅H₂tBu₃ ( 1 b ), Cp*=C₅Me₅ ( 1 c ) und Cp^4iPr=C₅HiPr₄ ( 1 d )). The reaction proceeds via the activation of P₄ by Cp^R radicals mediated by transition metals. The newly formed organic derivatives of P₄ have been comprehensively characterized by NMR spectroscopy and X‐ray crystallography.     

[Cp2Ln(m-h1:h2-OC(SR)=CPh2 )]2 的合成和表征

[Cp2Ln（μ-SR）]2 was reacted with Ph2C=C=O to yield ketene mono-insertion products [Cp2Ln（μ-η1：η2-OC（SR）=CPh2）]2 [R=Bn, Ln=Yb （1）, Er （2）, Y （3） and R--Ph, Ln=Yb （4）], indicating that the reactions of organolanthanide thiolates with ketenes are independent of the nature of the thiolate ligand and the ketene as well as the reaction condition. These reactions could provide an efficient method for the synthesis of organolanthanide complexes with the a-thiolate-substituted enolate ligand. All these complexes were characterized by elemental analysis and spectroscopic properties and the structure of complex 1 was determined through X-ray single crystal diffraction analysis.     

Synthèse électrochimique du cycle époxydique. Communication préliminaire

The polarographic behaviour of ditosyloxy alkanes TsO(CH₂)_nOTs in aprotic medium suggests that intramolecular cyclisation takes place after reductive cleavage of a single SO₂? O bond at the dropping electrode. This hypothesis was verified by controlled potential electrolysis of the lower homologues at a mercury cathode. High yields of epoxy compounds are obtained by this method.     

Synthesis and Characterization of Cobalttelluride Clusters with the Cubic Body-Centered Co9Te6(CO)8 Core

Reduction of Cp₂NbTe₂H (Cp=tBuC₅H₄) with CH₃Li results in a red-violet solution which reacts with Co₂(CO)₈ to give the neutral cluster {Cp₂Nb(CO)}₂[Co₉Te₆(CO)₈] (2) and a mixture of salts, from which [Na(THF)₆][Co₉Te₆(CO)₈] (4) was obtained by crystallization from THF in very poor yield, probably due to Na impurities in CH₃Li. Clusters 2 (123 valence electrons) and 4 (122 valence electrons) possess hexacapped cubic Co@Co₈ cores. The structure of 2 was identified by comparison of spectroscopic data with those of parent clusters: Two Cp₂Nb(CO) fragments are fixed at two opposite ₄-Te bridges of the Co₉Te₆(CO)₈ skeleton. A crystal structure determination of 4 shows this compound to contain discrete ions. Nearly equal diameters of ca. 10.5Å for the [Co₉Te₆(CO)₈]^– anion and the octahedral [Na(THF)₆]⁺ cation as well as electrostatic interactions between them and attractive C–HO contacts may be responsible for the formation of layers throughout the crystal.     

Preparation and properties of dicyclopentadienylniobium(III) chloride

The preparation of an air-sensitive 16-electron complex, Cp₂NbCl, is described. Its main property is easy transformation to 18-electron mononuclear compounds. Cp₂Nb(=O)Cl and Cp₂Nb(CO)Cl are obtained in oxidation and carbon monoxide gas addition processes, respectively. The physical properties of these complexes are described.     

Use of microwave technology for the synthesis of organotitanium(IV) and organozirconium(IV) complexes with HPOH,HO<Superscript>∩</Superscript>N<Superscript>∩</Superscript>OH and HO<Superscript>∩</Superscript>N<Superscript>∩</Superscript>SH type of ligands

Synthesis and characterization of titanium(IV) and zirconium(IV) complexes of the types Cp₂M(Cl)(HPO), Cp₂M(HPO)₂, Cp₂M(O^∩N^∩O) and Cp₂M(O^∩N^∩S) (where M represents titanium or zirconium and HPO, O^∩N^∩O and O^∩N^∩S represent the donor sets of the ligands) have been reported. These new derivatives have been prepared by the reactions of titanocene dichloride or zirconocene dichloride with 2-hydroxy-N-phenyl benzamide(HPOH), 1-[(2-hydroxyphenyl)-1-N-phenylamino]hydrazine-carboxamide (HO^∩N^∩OH) and 2-hydroxy-N-phenyl benzamide benzothiazoline (HO^∩N^∩SH) in different molar ratios. The ligands and their complexes have been characterized by the elemental analyses, conductance measurement, molecular weight determinations and spectral studies. On the basis of electronic, I.r., ¹H.-n.m.r. and ¹³C.-n.m.r. spectral studies, trigonal bipyramidal and octahedral geometries have been proposed for the resulting complexes. All the ligands and their complexes have been screened for their biological activity on several pathogenic fungi and bacteria and were found positive in this respect.     

Bis(η5‐isopropyltetramethylcyclo­pentadienyl)(tetrahydroborato‐κ3H,H′,H′′)(tetrahydrofuran‐O)‐samarium(III): a lanthanidocene complex with a tridentate tetrahydroborato ligand

The lanthanidocene complex [Sm(BH₄)(C₁₂H₁₉)₂(C₄H₈O)], (I), shows a distorted tetrahedral arrangement around the central Sm^III atom. It consists of two η⁵‐isopropyltetramethylcyclopentadienyl ligands, one tetrahydroborato (BH₄^?) ligand bridging via H atoms to the lanthanide atom and one coordinating tetrahydrofuran (thf) molecule. The BH₄^? unit of (I) coordinates as a tridentate ligand with three bridging H atoms and one terminal H atom [Sm—B—H4 176 (2)°]. The η⁵‐isopropyl­tetra­methylcyclopentadienyl ligands of this bent‐sandwich complex [Cp1—Sm—Cp2 133.53 (1)° where Cp denotes the centroid of the cyclopentadienyl ring] adopt staggered conformations.     

One-Step Synthesis and Schlenk-Type Equilibrium of Cyclopentadienylmagnesium Bromides

In the in situ Grignard metalation method (iGMM), the addition of bromoethane to a suspension of magnesium turnings and cyclopentadienes [C₅H₆ (HCp), C₅H₅-Si(iPr)₃ (HCp^TIPS)] in diethyl ether smoothly yields heteroleptic [(Et₂O)Mg(Cp^R)(μ-Br)]₂ (Cp^R=Cp ( 1 ), Cp^TIPS ( 2 )). The Schlenk equilibrium of 2 in toluene leads to ligand exchange and formation of homoleptic [Mg(Cp^R)₂] ( 3 ) and [(Et₂O)MgBr(μ-Br)]₂ ( 4 ). Interfering solvation and aggregation as well as ligand redistribution equilibria hamper a quantitative elucidation of thermodynamic data for the Schlenk equilibrium of 2 in toluene. In ethereal solvents, mononuclear species [(Et₂O)₂Mg(Cp^TIPS)Br] ( 2’ ), [(Et₂O)_nMg(Cp^TIPS)₂] ( 3’ ), and [(Et₂O)₂MgBr₂] ( 4’ ) coexist. Larger coordination numbers can be realized with cyclic ethers like tetrahydropyran allowing crystallization of [(thp)₄MgBr₂] ( 5 ). The interpretation of the temperature-dependency of the Schlenk equilibrium constant in diethyl ether gives a reaction enthalpy ΔH and reaction entropy ΔS of −11.5 kJ mol⁻¹ and 60 J mol⁻¹, respectively.     

Activation of biscyclopentadienyl hydride complexes of titanium and aluminum by NH- and OH-acids in the reactions of hydrogenation of olefins. Crystal and molecular structures of {(η5−Cp)2Ti(μ−H)2AlH]μ−N(C2H4)4O]}2 and [(η5−Cp)2Ti(μ−H(2AlH]2(μ−OC2H4OMe)[(μ1:μ5−C5H4)Ti(μ5−Cp)(μ−H)]2*

The reactions of Cp₂TiH₂AlH₂·Et₂O (1) with HN(C₂H₄)₂O, HOC₂H₄OMe, and water afforded the complexes {Cp₂TiH₂AlH[μ-N(C₂H₄)₂O]}₂ (5), [Cp₂TiH₂AlH(μ-OC₂H₄OMe)]₂ (6) and (Cp₂TiH₂AlH)₂O (4), respectively. Compounds 5 and 6 are dimers containing bridging Al?E₂?Al fragments (E=N or O). Complex 6 in solution converted to the hexanuclear compound [(η⁵?Cp)₂Ti(μ?H(₂AlH]₂(μ?OC₂H₄OMe)[(μ¹:μ⁵?C₅H₄)Ti(μ⁵?Cp)(μ?H)]₂ (8). The structures of complexes 5 and 8 were established by X-ray diffraction analysis. The rates of hydrogenation of hex-1-ene were determined using compounds 4–6 and the complexes [Cp₂TiH₂AlH(NEt₂)]₂ and [Cp₂TiH₂AlH(OEt)]₂ as catalysts. The probable mechanism of hydrogenation with the participation of bimetallic hydride complexes of aluminum and titanocene is discussed.