Intramolecular coordination of an alkene to a mixed dicyclopentadienyl benzyl zirconium cation studied by NMR spectroscopy

Benzylation of [Zr(¿5-C5H5){¿5-C5H4SiMe2(CH2CH:CH2)}Cl2] 1 yields [Zr(¿5-C5H5){¿5-C5H4SiMe2(CH2CH:CH2)}(CH2Ph)2] 2, which reacts with either B(C6F5)3 or [Ph3C][B(C6F5)4] to generate the same 14-electron cationic species, [Zr(¿5-C5H5){¿5-C5H4SiMe2(CH2CH:CH2)}(CH2Ph)]+ 3, which was fully characterized by 1H, 13C NMR and 1H DNMR spectroscopy. 3 Was fluxional in soln. Stabilization of 3 occurs by interaction of the ¿-bonding alkene orbital with the vacant 2a1 zirconium orbital and simultaneous overlapping of the HOMO ¿ alkene orbital with the vacant zirconium orbital of the same symmetry, b2. These interactions result in delocalized electron d. in the Zr-C-C system.Financial support of our work by DGICTY (Project PB- 92/0178-C) and CAM(I+D0034/94) is gratefully acknowledged. G. H. is grateful to the University of Alcala for financial support and the Alexander von Humboldt-Stiftung for a fellowshi

Reactivity of vinyl and alkynyl zirconium complexes with the di-ansa-[1,1′,2,2′-bis(dimethylsilanediyl) dicyclopentadienyl] ligand

Vinylation of the chloro–ethyl and dichloro zirconium complexes [Zr(CpSi2Cp)ClX] (CpSi2Cp=1,1′,2,2′-(SiMe2)2(η5-C5H3)2; X=Et, Cl) with one or two equivalents of Mg(CH=CH2)Cl gave the new zirconacyclopentane [Zr(CpSi2Cp){η2-CH2-(CH2)2-CH2}] and (η4-butadiene)zirconium [Zr(CpSi2Cp){η4-(butadiene)}] complexes, respectively. Addition of a toluene solution of PhC=CPh to the zirconacyclopentane compound afforded the zirconacyclopentadiene derivative [Zr(CpSi2Cp){η2-(CPh=CPh-CPh=CPh)}]. Reaction of the chloro–ethyl zirconium complex with LiC=CPh afforded the alkynyl compound [Zr(CpSi2Cp)Et(C=CPh)] which reacted with CN(2,6-Me2C6H3) to give the insertion product [Zr(CpSi2Cp)(C=CPh){η2-C(Et)=N(2,6-Me2C6H3)}]. Reactions of the chloro–ethyl [Zr(CpSi2Cp)EtCl] and alkynyl-ethyl [Zr(CpSi2Cp)Et(C=CPh)] complexes with the Lewis acid B(C6F5)3 yielding various cationic species have been monitored by 1H-NMR spectroscopy. The new complexes reported and their intermediates have been identified by IR and 1H- and 13C-NMR spectroscopy

Reactivity of the dinuclear fulvalene cyclopentadienyl zirconium cationic species \ud [{Zr(η5-C5H5)}2(μ-CH2)(μ-Cl)(μ-η5-C5H4-η5-C5H4)]+ with isocyanides and carbon monoxide: insertion reactions, spectroscopic characterization and synthetic aspects

The dinuclear cationic zirconium compound [{Zr(η5-C5H5)}2(μ-CH2)(μ-Cl)(μ-η5-C5H4-η5-C5H4)][BMe(C6F5)3] 1 reacts in dichloromethane at −78 °C with three equivalents of RNC (R=tBu, 2,6-Me2C6H3) via insertion into the Zr-μ-methylene bond to give the new zirconium cationic species [{Zr(η5-C5H5)}2(Cl)(CNtBu){μ-[η2-CN(tBu)-CH2-η2-CN(tBu)}(μ-η5-C5H4-η5-C5H4)][BMe(C6F5)3] 2 and [{Zr(η5-C5H5)}2(Cl){CN(2,6-Me2C6H3)}[μ-η2-{CN(2,6-Me2C6H3)}-CH2-η2-{CN(2,6-Me2C6H3)}](μ-η5-C5H4-η5-C5H4)][BMe(C6F5)3] 3, whereas reaction with CO affords the ketene compound [{Zr(η5-C5H5)}2(μ-Cl){μ-OC(CH2)}(μ-η5-C5H4-η5-C5H4)][BMe(C6F5)3] 4. The new complexes reported herein were characterized by elemental analysis and IR and NMR spectroscopy.Financial support by DGICYT (Project PB97-0776)\ud is gratefully acknowledged. E.R. acknowledges MECFPI\ud for the award of Fellowshi

Synthesis of bis(tert-butyl)cyclopentadienyl derivatives of titanium and zirconium. NMR spectra and dynamic behavior of the base-free [Zr(1,3-tBu2-µ5-C5H3)(CH2Ph)2]+ cation

Reaction of Si(1,3-tBu2-C5H3)Me3 with MCl4 (M = Ti, Zr) in toluene or hexane at room temp. affords the new trichloromonociclopentadienyl-type derivs. [M(1,3-tBu2-η5-C5H3)Cl3] [M = Ti (2), Zr (3)]. Treatment of complexes 2 and 3 with appropriate alkylating reagents in hexane gives the 1,3-di(tert-butyl)cyclopentadienyl trialkyl titanium and zirconium complexes [M(1,3-tBu2-η5-C5H3)R3] [M = Ti, R = CH3, CH2Ph; M = Zr, R = CH3, CH2Ph (7), CH2CMe2Ph]. Interestingly, when 2 reacts with 3.1 equiv of LiCH2CMe2Ph in hexane at room temp. the ring-tert-butyl-metalated complex [Ti(1-tBu-3-CMe2CH2-η5-C5H3) (CH2CMe2Ph)2] was isolated in 90% yield. The cationic mono(1,3-di-(tert-butyl)cyclopentadienyl) dibenzyl zirconium species [Zr(1,3-tBu2-η5-C5H3)(CH2Ph)2]+, generated in situ by reaction of the tribenzyl complex 7 with B(C6F5)3 or [CPh3]+[B(C6F5)4]- reagents, is reported and their dynamic NMR behavior in CD2Cl2 solns. at low temps. is studied.Financial support for this research by DGICYT (Project\ud PB92-0178-C) is gratefully acknowledged. J.I.A.\ud acknowledges Repsol Petróleo S.A. for a fellowship

Dinuclear cationic zirconium complexes with the fulvalene ligand. Synthesis and reactivity

The reaction of B(C6F5)3 with the tetramethyl zirconium fulvalene derivative [Zr(C5H5)(CH3)2]2(μ-η5:η5-C10H8) 1a in CH2Cl2 at −60°C gives the cationic compound [{Zr(C5H5)}2(μ-CH3)(μ-CH2)(μ-η5:η5-C10H8)]+[BMe(C6F5)3]−2a. A similar reaction using the 1,3-di(tert-butyl) cyclopentadienyl derivative [Zr(1,3-tBu2-C5H3)(CH3)2]2(μ-η5:η5-C10H8) 1b affords a mixture of compounds, none of them being isolable as pure substances. However, monitoring the reaction of B(C6F5)3 with 1b by variable temperature NMR spectroscopy, between −80°C and 25°C, permits the observation, at low temperature, of the intermediate dimethyl μ-methyl cationic species [{Zr(1,3-tBu2-C5H3)(CH3)}2(μ-CH3)(μ-η5-η5-C10H8)]+8b which decomposes with evolution of methane to give the μ-methylene, μ-methyl complex [{Zr(1,3-tBu2-C5H3)}2(μ-CH3)(μ-CH2)(μ-η5:η5-C10H8)]+[BMe(C6F5)3] 2b. In dichloromethane or chloroform complexes 2a and 2b undergo slow conversion to the μ-chloro, μ-methylene derivatives [{ZrCp′}2(μ-Cl)(μ-CH2)(η5:η5-C10H8)]+[BMe(C6F5)3]− (Cp′ = C5H53a, 1,3-tBu2-C5H33b) by a halide abstraction process. Prolonged exposure of 3b to chlorocarbons gives the dichloro μ-chloro compound [{Zr(1,3-tBu2-C5H3)Cl}2(μ-Cl)(μ-η5:η5-C10H8)]+[BMe(C6F5)3]−9b. The addition of an excess of donor ligands to a solution of 2a in dichloromethane-d2 at −60°C affords the cationic adducts [{Zr(C5H5)}2(CH3)L(μ-CH2)(μ-η5:η5-C10H8)]+[BMe(C6F5)3]− [L = PMe3 (4a), PMe2Ph (5a), PPh3 (6a), THF (7a)] obtained as a mixture of syn- and anti-isomers. The compound 5a can be isolated as an analytically pure sample when this reaction is carried out in CH2Cl2.British Counci

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))

Alkyl and alkylidene imido cyclopentadienyl tungsten complexes

This paper reports the alkylation of the cyclopentadienyl imido tungsten complexes [WCp′(NtBu)Cl3] (Cp′=η5-C5H5, η5-C5Me5) with β-hydrogen containing alkyl groups to render halo alkyl and trialkyl complexes [WCp′(NtBu)Cl3−nRn] (R=Et, n-Pr). Thermal decomposition of the trialkyl compounds gives the alkylidene derivatives [WCp′(NtBu)(CHR)(CH2R)] (R=Me, Et) by α-hydrogen elimination. All of the compounds were characterized by NMR spectroscopy and the molecular structure of [W(η5-C5Me5)(NtBu)Et3] was determined by X-ray diffraction methods.The authors acknowledge DGICYT (project PB97-0677) for financial support

Neutral and cationic di(tert-butyl) cyclopentadienyl titanium, zirconium and hafnium complexes. Dynamic NMR study of the ligand-free cations [M(1,3-tBu2-η5-C5H3)(η5-f5H5)(CH3)]+(M=Zr, Hf)

Group 4 metal complexes containing the di(tert-butyl)cyclopentadienyl ligand (l,3-tBu2-r/5-CsH3) have been synthesized. The\ud reaction of a mixture of 1,3- and 1,4-di(tert-butyl)cyclopentadiene isomers with KH in THF at -78°C gives the salt K+[(1,3 -\ud tBu2CsH3)]-(THF)I_3 2 as a white solid. Treatment of 2 with chlorotrimethylsilane in a 1:1 molar ratio gives the air-stable\ud trimethylsilylcyclopentadienyl derivative Si(1,3-tBu2C5H3XCH3)3 3. The silyl derivative 3 is an excellent precursor for monocyclopentadienyl\ud trichlorotitanium and zirconium compounds M(1,3 -t Bu 2-r/5-C 5 H 3)C13 [M = Ti (4), Zr (5)]. Addition of a stoichiometric amount\ud of water in the presence of NEt 3 to a toluene solution of 4 affords the oxo trimer compound [Ti(1,3-tBu2-~75 - CsH3)CI( p,-O)] 3 6. The\ud reaction of 4 with 2 equiv, of LiMe affords the chloro dimethyl derivative Ti(1,3-tBu2-'r/5-CsH3)CI(CH3)2 7. The mixed dicyclopentadienyl\ud compounds M(1,3-tBu2-r/5-CsH3XCsHs)CI2 [M = Ti (8); Zr (9)] were prepared by reaction of complexes 4 and 5 respectively with\ud TI(CsHs). Treatment of complexes (8) and (9) with the appropriate alkylating reagent and molar ratio, in hexane at -78 °C, gives the\ud chloro alkyl derivatives M(1,3-tBu2-@-C5H3XCsHs)CIR [M = Ti, R = Me (10); M = Zr, R = Me (11), Bz (12)] or the dialkyl\ud complexes M(1,3-tBu2-@-CsH3)(CsHs)Rz [M = Ti, R = Me (13); M = Zr, R = Me (14), Bz (15), Nf (16)]. When 8 reacts with 2 equiv.\ud of MgBz2(THF) 2 or LiCH2CMe2Ph the metallacyclic complexes Ti(1-tBu-3-CMe2CH~-r/5-C~Ha)(CsHs)R [R = Bz (17); Nf (18)] were\ud isolated as red oils at room temperature, with the elimination of toluene or ten-butyl benzene respectively. The previously reported\ud cationic mono 1,3-di(tert-butyl)cyclopentadienyl dibenzyl zirconium species [Zr(1,3 -t Bu 2-'05-C 5 H 3 XCH 2 Ph) 2 ] + (19) can be stabilized\ud by reaction with tBuNC or PMe 3, in CD2C12 at -78°C, and the formation of the new cationic species [Zr(1,3-tBu2-r/5-\ud CsHa)(L)(CH2Ph)2] + [L=tBuNC (20); PMe 3 (21)] was identified by NMR spectroscopy. The reaction of B(CrFs) 3 with the\ud monocyclopentadienyl trimethyl derivatives M(1,3-tBu2-r/5-CsH3XCH3)3 [M = Ti (22), Zr (23)], in the presence of PMe 3, gives the\ud cationic species [M(I,3-tBu2-@-C~H3)(PMe3)2(CH3)2] + [M = Ti (24); Zr (25)], obtained as orange-yellow solids, stable at room\ud temperature. The reaction of B(C6Fs) 3 with the metallocene dimethyl derivatives M(1,3-tBu2-r/5-CsHa)(@-CsHs)(CH3)z [M = Zr (14);\ud Hf (26)], in a 1:1 molar ratio and in hydrocarbon solvents gives the cationic derivatives [M(1,3-tBu2-@-CsH3)(@ -\ud CsHsXCH3)]+[(CH3)B(CrFs)3] - [M = Zr (27); Hf (28)] as yellow oils which can be stored for weeks under an inert atmosphere. When\ud the same reactions of (14) and (26) with B(C6Fs) 3 are carried out in a 2:1 molar ratio at room temperature, the complexes\ud {[M(1,3-tBu2-@-CsH3X@-CsH5)Me]2(/.L-Me)}[MeB(C6Fs)3] [M =Zr (29), Hf (30)] can be obtained as a mixture of syn- and\ud anti-isomers as shown by NMR spectroscopic observations. The formation of (29) and (30) implies the stabilization of the 14-electron\ud cationic intermediate by interaction with one methyl group of the neutral complexes (14) and (26). Complexes (27) and (28) undergo\ud heterolytic dissociation of the Metal-MeB(C6Fs) 3 bonds, leading to the formation of the free [M(I,3-tBu2-r/5-CsH3)(r/5-CsHs)(CH3)] +\ud 14-electron species, verified by 1H DNMR spectroscopy. When compound (27) was heated at 50°C the metallacyclic cation\ud [Zr(1-tBu-3-CMezCH2-@-C5H3)(@-CsHs)] + (31) was formed. The alkyl derivatives synthesized and reported herein, activated with MAO, B(C6Fs) 3 or [Ph3C][B(C6Fs)4], polymerize ethylene with very low activity. The molecular structure of [Ti(1,3-tBu2-r/5-\ud C5H3)C1(/x-O)] 3 6 has been determined by X-ray diffraction methods.Financial support for this research by DGICYT (Project PB92-0178C) is gratefully acknowledged. J.I.A.\ud acknowledges Repsol Petróleo S.A. for a fellowship. A.M. is grateful to Consejeria Educaci6n (CAM) for a fellowship

Regioselective formation of\ud [2-(η5-cyclopentadienyl)-2-fluorenylpropane]-titanium complexes:\ud precursors, synthesis, structure and reactivity

The 2-cyclopentadienyl-2-fluorenylpropane ligand has been converted into the monometalated derivatives M[CMe2(C5H4)(C13H9)] (M=Li, 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(η5-C5H4)(C13H9)}Cl3]. Reaction of the thallium derivative with [Ti(η5-C5R5)Cl3] afforded the ‘mixed-ring’ dicyclopentadienyl complexes [Ti{CMe2(η5-C5H4)(C13H9)}(η5-C5R5)Cl2] (R=H, Me), whereas the reaction of TiCl4 with two equivalents of the lithium compound led to the dicyclopentadienyl complex [Ti{CMe2(η5-C5H4)(C13H9)}2Cl2]. The monocyclopentadienyl compound [Ti{CMe2(η5-C5H4)(C13H9)}Cl3] was readily hydrolyzed to give [Ti{CMe2(η5-C5H4)(C13H9)}Cl2]2(μ-O) in wet acetone (0.5% H2O). The dicyclopentadienyl derivative [Ti{CMe2(η5-C5H4)(C13H9)}(η5-C5Me5)Cl2] was further converted into [Ti{CMe2(η5-C5H4)(C13H9)}(η5-C5Me5)Me2] by alkylation with LiMe. Structural data of the titanium complexes demonstrate the η5-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(η5-C5H4)(C13H9)}2Cl2]

Cyclopentadienyl dithiocarbamate and dithiophosphate molybdenum and tungsten complexes

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