Monopentamethylcyclopentadienyl isocyanide, amine and imido tantalum(V) complexes. X-ray crystal structure of [TaCp*Cl4(CN-2,6-Me2C6H3)]

[TaCp★Cl4](Cp★ = η5-C5Me5) reacts with isocyanides and amines to give the pseudo-octahedral adducts [TaCp★Cl4L] (L = 2,6-Me2C6H3NC, 1; 2,4,6-Me3C6H2NC, 2; tBuNC, 3; or C6H5NH2, 4). Reduction of 1, or alternatively of [TaCp★Cl4] in the presence of stoichiometric amounts of isocyanide, with two equivalents of Na/Hg gives the diamagnetic pseudo-octahedral tantalum(III) complex, [TaCp★Cl2(CN-2,6-Me2C6H3)35. Reaction of 4 with two equivalents of LiNEt2 affords the pseudo-octahedral imido complex [TaCp★Cl2(NC6H5). 6. All the complexes were characterized by usual IR and NMR spectroscopic methods and the molecular structure of I was confirmed by X-ray diffraction methods

Monopentamethylcyclopentadienyl isocyanide, amine and imido tantalum(V) complexes. X-ray crystal structure of [TaCp*Cl4(CN-2,6-Me2C6H3)]

[TaCp★Cl4](Cp★ = η5-C5Me5) reacts with isocyanides and amines to give the pseudo-octahedral adducts [TaCp★Cl4L] (L = 2,6-Me2C6H3NC, 1; 2,4,6-Me3C6H2NC, 2; tBuNC, 3; or C6H5NH2, 4). Reduction of 1, or alternatively of [TaCp★Cl4] in the presence of stoichiometric amounts of isocyanide, with two equivalents of Na/Hg gives the diamagnetic pseudo-octahedral tantalum(III) complex, [TaCp★Cl2(CN-2,6-Me2C6H3)35. Reaction of 4 with two equivalents of LiNEt2 affords the pseudo-octahedral imido complex [TaCp★Cl2(NC6H5). 6. All the complexes were characterized by usual IR and NMR spectroscopic methods and the molecular structure of I was confirmed by X-ray diffraction methods

Cationic species derived from the η1-amidosilyl-η5-cyclopentadienyl dimethyl titanium complex. Crystal structure of [Ti{η5-C5H4SiMe2[η1-N(2,6-Me2C6H3)]}{CH2B(C6F5)2}(C6F5)]

Reactions of the η5-cyclopentadienyl-η1-amido dimethyl titanium derivative [Ti{η5-C5H4SiMe2[η1-N(C6H3Me2)]}Me2] (1) with tris(pentafluorophenyl)borane B(C6F5)3 in hexane at room temperature yield a thermally stable bright yellow microcrystaline solid identified by elemental analysis as [Ti{η5-C5H4SiMe2[η1-N(C6H3Me2)]}Me{MeB(C6F5)3}] (2). A solution of 1 in CD2Cl2 at −78°C affords the ion-pair complex 2, while in C6D6 it is slowly converted into the new neutral complex [Ti{η5-C5H4SiMe2[η1-N(C6H3Me2)]}{CH2B(C6F5)2}(C6F5)] (3). Complex 3 is the unique product obtained after stirring compound 2 or a mixture of complex 1 and B(C6F5)3 in toluene or benzene for 12 h at room temperature. The molecular structure of complex 3 has been determined by diffraction methods

Methylbenz[e]indenyl asymmetric ansa-metallocene and silylamido zirconium complexes

2-(2-Methylbenz[e]indenyl)-2-cyclopentadienyl-propane [MeC13H8CMe2C5H5] (1) (MBICMe2Cp), was synthesized by reaction of LiMBI with 6,6-dimethylfulvene. The silyl derivatives [MeC13H8SiMeRCl] (R=Me 2, H 4) were isolated by reaction of 2-methylbenz[e]indene (LiMBI) with SiMeRCl2 and further reactions of 2 and 4 with NaCp afforded the silyl-bridged compounds [MeC13H8SiMeRC5H5] (R=Me 3, H 5). Metallation of 1 and 3 with 2 equiv. of LiBu gave the dilithium salts Li2[MeC13H7EMe2C5H4)] (E=C 6, Si 7) which were reacted with ZrCl4(THF)2 to obtain the ansa-metallocenes [Zr(MeC13H7EMe2C5H4)Cl2] (E=C 8, Si 9). A similar reaction of 5 with 2 equiv. of LiBu provided a mixture of the two diastereomers [Zr{MeC13H7SiMeBuC5H4}Cl2] (10a, 10b). Analogous metallation of [MeC13H8SiMe2(NH-t-Bu)] gave Li2[MeC13H7SiMe2(N-t-Bu)] which was used to prepare the amidosilyl derivatives [M{MeC13H7SiMe2η-(N-t-Bu)}Cl2] (M=Zr 11, Ti 12) by reaction with ZrCl4(THF)2 and TiCl3(THF)3 and further oxidation with PbCl2 (Ti). All of the new complexes were characterized by elemental analysis and NMR spectroscopy, and the molecular structures of complexes 9 and 10a were studied by X-ray diffraction methods.Financial support of our work by MCyT (Project MAT2001-1309) is gratefully acknowledged. A.S. is grateful to Repsol-YPF for a fellowship

Heterodinuclear TiMo and TiW complexes bridged by the (dimethylsilanediyl) dicyclopentadienyl ligand

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 Madri

Diastereoselective insertion of isocyanide into the alkyl metal bond of methylbenz[e]indenyl ansa-zirconocene complexes

Alkylation of ansa-zirconocene [Zr{(η5-C5H5)SiMe2(MBI)}Cl2] (MBI = η5-2-Me−C13H7) with MgRCl gave the dimethyl complex [Zr{(η5-C5H5)SiMe2(MBI)}Me2], but unresolvable mixtures containing mono-alkylated compounds were obtained when bulkier alkyls were used. However pure dialkyl complexes [Zr{(η5-C5H5)SiMe2(MBI)}R2] (R = CH2Ph, CH2SiMe3) were easily obtained using K(CH2Ph) and Li(CH2SiMe3) as alkylating agents. Diastereoselective insertion into the MBI-unprotected Zr−R bond was observed when all of these dialkyl complexes were treated with 2,6-xylyl isocyanide to give the iminoacyl compounds [Zr{(η5-C5H5)SiMe2(MBI)}R{CR[η2-N-(2,6-xylyl)]}] (R = Me, CH2Ph, CH2SiMe3). All of the new complexes were characterized by NMR spectroscopy and the X-ray molecular structures of the dibenzyl and the imino-benzyl compounds were determined. The catalytic activity for ethene polymerization and ethene/1-hexene copolymerization of the dichloro zirconocenes [Zr{(η5-C5H5)EMe2(MBI)}Cl2] (E = C, Si), activated with methylalumoxane (MAO), was measured.Repsol-YP

Silyl and siloxanediyl cyclopentadienyl titanium and zirconium complexes: synthesis and reactivity. X-ray molecular structure of [Zr{η5-C5H4SiMe2(μ-OH)}(μ-Cl)Cl2]2

Chloro(dimethyl)silyl-η5-cyclopentadienyl group 4 metal complexes of the type [M(η5-C5H4Cl)Cl3] (Full-size image (<1 K)) react with thallium salts Tl(C5H4R) (R = H, SiMe3) to give mixed dicyclopentadienyl derivatives [M(η5-C5H4R)(η5-C5H4SiMe2Cl)Cl2], (M = Ti, R = H 3, R = SiMe34; M = Zr, R = H 5, R = SiMe36) in high yield. Hydrolysis of complexes 3 and 4 affords the dinuclear complexes [Ti(η5-C5H4R)Cl2]2{μ-[(η5-C5H4SiMe2)2O]}] [R = H 7, R = SiMe38) containing a siloxanyl bridge, by elimination of two equivalents of HCl. Reactions of complexes 1 with hydroxo containing reagents such as anhydrous LiOH and SiPh2(OH)2 give the derivatives [Ti(η5-C5H4SiMe2Cl)Cl2]2(μ-O)], 9 and Ti[μ-(η5-C5H4SiMe2OSiPh2-η1-O)]Cl2, 10 identified by analytical, spectrometric and spectroscopic data. Treatment of analogous complex 2 with water produces the dimeric monocyclopentadienyl zirconium trichloride adduct [Zr(η5-C5H4SiMe2OH)Cl3]2, 11. Compound 11 has been characterized by X-ray crystallography.Universidad de AlcaláConsejería de Educación de la Comunidad de Madri

Allylsilylcyclopentadienyl Group 4 metal complexes: synthesis, structure and reactivity

(Allyldimethyl)silyl-substituted cyclopentadiene C5H5SiMe2(CH2CH /CH2) (1) and indene C9H7 /1-SiMe2(CH2CH /CH2) (2)\ud were synthesized by reaction of SiMe2(CH2CH /CH2)Cl with NaC5H5 or LiC9H7, respectively. Metallation of 1 with n-BuLi and\ud TlOEt gave the corresponding lithium 3 and thallium 5 salts. The disilylcylopentadienes C5H4 /1-SiMe3 /1-SiMe2(CH2CH /CH2) (6)\ud and C5H4 /1,1-[SiMe2(CH2CH /CH2)]2 (7) were prepared by reaction of 3 with the corresponding chlorosilanes. Compound 7\ud reacted with TiCl4 to give the monocyclopentadienyl compound [Ti{h5\ud -C5H4SiMe2(CH2CH /CH2)}Cl3] (8), while 5 was used to\ud prepare the titanocenes [Ti(h5\ud -Cp){h5\ud -C5H4SiMe2(CH2CH /CH2)}Cl2] (Cp /C5H4SiMe2(CH2CH /CH2) 9, C5H5 10, C5Me5 11) by\ud reaction with the appropriate TiCpCl3 derivative. The related dicyclopentadienyl [Zr{h5\ud -C5H4SiMe2(CH2CH /CH2)}2Cl2] (12),\ud [Zr(h5\ud -C5H5){h5\ud -C5H4SiMe2(CH2CH /CH2)}Cl2] (13), and indenyl [Zr(h5\ud -C5H5){h5\ud -C9H6SiMe2(CH2CH /CH2)}Cl2] (14) zirconium\ud derivatives were isolated by reaction of ZrCl4 and Zr(h5\ud -C5H5)Cl3 /DME with the lithium salts 3 and 4, respectively.\ud Alkylation of the metallocene complexes using MeLi, MgMeCl, Mg(CH2Ph)Cl and Mg(CH2Ph)2(THF)2 afforded the monomethyl\ud titanium [Ti(h5\ud -C5H5){h5\ud -C5H4SiMe2(CH2CH /CH2)}ClMe] (15) and the dialkyl cyclopentadienyl [M(h5\ud -C5H5){h5\ud -C5H4SiMe2\ud (CH2CH /CH2)}R2] (R /Me, M /Ti 16, Zr 18; R /CH2Ph, M /Ti 20, Zr 22), [Zr{h5\ud -C5H4SiMe2(CH2CH /CH2)}2R2] (R /Me\ud 17, CH2Ph 21) and indenyl derivatives [Zr(h5\ud -C5H5){h5\ud -C9H6SiMe2(CH2CH /CH2)}R2] (R /Me 19, CH2Ph 23). The molecular\ud structure of 11 was studied by X-ray diffraction methods. The reactions of the dialkyl derivatives with B(C6F5)3 were monitored by\ud NMR spectroscopy at variable temperature. The catalytic activity of the dichloro zirconium complexes in the presence of\ud methylalumoxane (MAO) for ethylene polymerization was determined.Financial support of our work by MCyT (Project\ud MAT2001-1309) is gratefully acknowledged. G.H., G.M\ud and J.C are grateful to to the Alexander von HumboldtStiftung,\ud MEC and CAM for fellowships

Synthesis and characterization of new alkoxide and aryloxide derivatives of titanium and zirconium. X-ray molecular structure of [ZrCp2(OC6F5)2]

Lithium or sodium alkoxides MOR (R double bond; length as m-dashCH2CHdouble bond; length as m-dashCMe2; M double bond; length as m-dash Li1; Na2; R double bond; length as m-dash C6F5; M double bond; length as m-dash Li3 were prepared by reaction of the alcohols with n-butyl lithium or sodium metal in hexane. Reaction of a hexane suspension of3 with SiClMe, afforded SiMe3(OC6F5)4, whereas the reaction of 3 equivalents of C6F5OH with AlMe3 in hexane led to Al(OC6F5)35. Compounds1 or2 react with one equivalent of [TiCp*Cl2Me] (Cp*double bond; length as m-dash C5Me5) in toluene to give [TiCp*ClMe(OCH2CHdouble bond; length as m-dashCMe2)]6. Complex6 reacts with AlEtCl2 to give quantitatively [TiCp*Cl3]. In the presence of water, the hydrolysis of6 takes palce giving the μ-oxo compound [{(TiCp*Cl)(μ − O)}3]. [TiCp*Cl2Me] reacted with an excess of the alcohol C6F5OH to give [TiCp*(OC6F5)3]7. [ZrCp2Cl2] reacted with two equivalents of pentaflurophenol in the presence of aniline to give the dialkoxide [ZrCp2(OC6F5)2]8. When the same reaction was carried out in a 1:1 molar ratio, a mixture of8 and the chloroalkoxide [ZrCp2Cl(OC6F5)]9 was obtained. A cleac reaction takes place when the μ-oxo compound [(ZrCp2Me)2(μ-O)] is treated with two equivalents of pentaflurophenol, leading to the isolation of the alkoxo complex [{ZrCp2(OC6F5)}2(μ-O)]10. The methylalkoxo derivative [ZrCp2Me(OC6F5)]11, was obtained by rection of [ZrCp2ClMe] with one equivalent of3. Alternative methods can be also be followed to synthesize8 and11. The crystal and molecular structure of8 has been determined by X-ray diffraction methods. The most interesting feature of this structure is the disposition of the (C6F5) ring planes, which are located practically on the reflection plane defined by O(1), Zr(1) and O(1)′

Pentamethylcyclopentadienyl halo- and alkyl-alkoxo tantalum(V) complexes. Crystal structure of TaCp*(CH2SiMe3) 2{η2-O(2-CH2-6-MeC6H3)}

Reaction of TaCp" C! 4 with MOR (M - Li, Na) in different molar ratios gives halo alkoxides TaCp" CI,(OR)4_,, (n - 3: R -tBu 1; $iPh 3 2; 2,6-Me2C6H 3 3; n -- 2: R -~Bu 4; SiPh 3 5; 2,6-Me2C6H3 6; a - !: R - SiMe 3 7) in good yields. The alkylidene complex TaCp'(CH2SiMe,02(CHSiMe ~) is hydrolyzed in the presence of traces of water to give the oxo dialkyl derivative [TaCp'(CH2SiM¢3)~O],, 8, and reacts with I equivalent of 2,6-MezC6H~NC affording a new 'q2-iminoacyi compound TaCp" (CH 2$iMe3XCHSiMe3){~ 2"C(CH 2SiMe3 ) = N(2,6"MeaC6 H 3)} 9. Reactions of TaCp "(CH 2SiMe3)a(CHSiMe3 ) with I equivalent of C6HsOH and 4-MeC6H3(OH) 2 result in the formation of the alkyl phenoxo TaCp'(CH2SiMe3)3(OC6Hs) 10 and 4-methyl pyrocatecholate TaCp'(CH2SiMe~)2(O2C6H3Me) 11, whereas the related re,",,:don with 2,6-Me2C6H 3OH leads to the cyclic alkyi-aikoxo compound TaCp (CH2SiMej)2(~2-O(2-CH2-6-MeC6H3)) 12. All the complexes were characterized by IR and NMR (tH and 13C) spectroscopy. The crystal and molecular structure of 12 has been determine~i. C~ystals of 12 are triclinic, space group P'[ with Z - 2 in a unit cell of dimensions a- 9.151(5) ~, b- 11.835(5) ~,, c- 14.045(4) A, a- 89.35(3) °, /3- 72.34(3) 0 and 'y-88.51(4) °, V- 1449(I) ~s. Final values of R -0.025 and Rw -0.0655 were obtained from 554'7 reflections measured (50'70, > 2o'(i))