Syntheses and Crystal Structures of Dichlorobis[tetramethyl(phenyl)cyclopentadienyl]titanium(IV) and Chlorobis[tetramethyl(phenyl)cyclopentadienyl]titanium(III)

Horáček, Michal; Polášek, Miroslav; Kupfer, Volkmar; Thewalt, Ulf; Mach, Karel

doi:10.1135/cccc19990061

Cited by 20 publications

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“…Essential molecular geometric parameters are given in Table , and the PLATON drawing of 5 is shown in Figure . The structure of 5 shows the pseudo-trigonal coordination around the titanium atom common for persubstituted titanocene monochlorides having the η 5 -C 5 Me 4 - t -Bu, η 5 -C 5 Me 4 Ph, and η 5 -C 5 Me 4 SiMe 3 ancillary ligands .…”

Section: Resultsmentioning

confidence: 99%

Effect of the Trimethylsilyl Substituent on the Reactivity of Permethyltitanocene

et al. 2007

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The presence of a trimethylsilyl substituent in place of one of the methyl groups of each of the cyclopentadienyl ligands of decamethyltitanocene enhances the thermal stability of the resulting complex, [Ti II {η 5 -C 5 Me 4 (SiMe 3 )} 2 ] (1), and controls the products formed in thermolysis of its methyl derivatives. Titanocene 1 was found to be stable in toluene solution up to 90 °C, while under vacuum at 140 °C it liberated hydrogen to give the asymmetrical doubly tucked-in titanocene [Ti II {η 3 :η 4 -C 5 Me 2 (SiMe 3 )(CH 2 ) 2 }-{η 5 -C 5 Me 4 (SiMe 3 )}] (3). The mono-and dimethyl derivatives of 1, the complexes [Ti III Me{η 5 -C 5 Me 4 -(SiMe 3 )} 2 ] (5) and [Ti IV Me 2 {η 5 -C 5 Me 4 (SiMe 3 )} 2 ] (6), undergo thermolysis at lower temperature than do the corresponding permethyltitanocene derivatives and eliminate hydrogen from their trimethylsilyl group. Thus, the known [Ti III {η 5 :η 1 -C 5 Me 4 (SiMe 2 CH 2 )}{η 5 -C 5 Me 4 (SiMe 3 )}] (4) was obtained from 5, and compound 6 afforded [Ti II {η 6 :η 1 -C 5 Me 3 (CH 2 )(SiMe 2 CH 2 )}{η 5 -C 5 Me 4 (SiMe 3 )}] (7) at only 90 °C, both with liberation of methane. Crystal structures of 3, 5, and 7 were determined. DFT calculations for titanocene 1 revealed that the metal-cyclopentadienyl bonding is accomplished via a three-centerfour-electron orbital interaction. An auxiliary long-range Si-C bond interaction with the Ti center was also established, providing a reason for the enhanced thermal stability of 1. The molecular orbitals participating in the exo methylene-titanium bonds for 3 and 7 are also three-centered and are compatible with the assignment of their activated ligands to η 3 :η 4 -allyldiene and η 6 -fulvene structures, respectively. Qualitatively, the much higher thermal stability of 3 and 7 compared to that of 1 is due to the exploitation of four d orbitals in the bonding molecular orbitals for 3 and 7 versus only two d orbitals for 1.

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Section: Resultsmentioning

confidence: 99%

Effect of the Trimethylsilyl Substituent on the Reactivity of Permethyltitanocene

et al. 2007

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“…0.408(3) Å for Si1 in 13 ), and the geometry of the titanocene skeleton of 12 differs only negligibly from that of [TiCl(η 5 -C 5 Me 5 ) 2 ]. 18c,d The trigonally coordinated Ti(III) atoms tend to dimerize through the electronegative substituents but only for derivatives having up to two methyl groups per one cyclopentadienyl ring; highly methylated titanocene monohalides, 18c,21a-c monoalkoxides, 18a,c,21d and permethylated SiMe 2 -bridged ansa -titanocene monochloride remain monomeric 18d. The side placement of the ansa -chain has been observed in permethyl-substituted titanocene monochlorides with bridging 1,2,5-trimethylpentane-1,5-diyl and 4,5-dimethyloct-2-ene-1,8-diyl ansa -chains 21e. In 13 , the bending of the methoxytitanium bond at the carbon atom is smaller (Ti−O−C27 165.0(2)°) than in [Ti(OCMe 3 )(η 5 -C 5 HMe 4 ) 2 ] (162.2(1)°) 21d…”

Section: Resultsmentioning

confidence: 99%

Reduction-Induced Cyclization and Redox Reactions of Fully Methylated Titanocene Dichlorides Bearing Pendant Alkenyldimethylsilyl Groups, [TiCl₂{η⁵-C₅Me₄(SiMe₂R)}₂] (R = Vinyl and Allyl)

et al. 2002

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Reduction of titanocene dichlorides bearing (ω-alkenyl)dimethylsilyl substituents [TiCl 2 {η 5 -C 5 Me 5 (SiMe 2 R)} 2 ], where R ) CHdCH 2 (3) and CH 2 CHdCH 2 (4), affords highly reactive Ti(II) intermediates, which immediately undergo intramolecular reactions with the pendant double bonds in a way dependent on the length of the alkenyl chain. The reduction of 4 with magnesium at 60 °C affords cleanly the cyclopentadienyl-ring-tethered titanacyclopentane, [Ti(η 1 :η 1 :η: 5 η 5 -C 5 Me 4 SiMe 2 CH(Ti)CH(Me)CH(Me)CH(Ti)SiMe 2 C 5 Me 4 ] (5), which can be opened by HCl to an ansa-titanocene dichloride with a six-membered saturated bridging chain, [TiCl 2 -{η: 5 η 5 -C 5 Me 4 SiMe 2 CH 2 CH(Me)CH(Me)CH 2 SiMe 2 C 5 Me 4 ) 2 }] (6). An analogous reaction of 3 can be accomplished at low temperatures and only to some extent, providing a mixture of titanacyclopentane complex [Ti(η 1 :η 1 :η: 5 η 5 -C 5 Me 4 SiMe 2 CH(Ti)CH 2 CH 2 CH(Ti)SiMe 2 C 5 Me 4 ] (10) and the fluxional η 2 -alkene complex [Ti(η 5 -C 5 Me 4 SiMe 2 CHdCH 2 )(η 2 :η 5 -C 5 Me 4 SiMe 2 CHd CH 2 )] (9). At 60 °C, the reduction of 3 yields a mixture of ansa-η 2 -alkene complex [Ti{η 2 : η 5 :η 5 -C 5 Me 4 SiMe 2 CH 2 CHdCHCH 2 SiMe 2 C 5 Me 4 }] (7) and the product of a hydrogen loss, the doubly tethered, paramagnetic η 3 -allyl Ti(III) complex [Ti{η 3 :η 5 :η 5 -C 5 Me 4 SiMe 2 CHCHd CHCH 2 SiMe 2 C 5 Me 4 }] (8). When the reduction of 3 with magnesium is carried out in the presence of bis(trimethylsilyl)ethyne as the proton acceptor, 8 is obtained as the sole isolated product. Complex 8 reacts with protic reagents such as HCl and methanol under protonation/ decomplexation of the allyl system to give the d 1 paramagnetic complexes [TiX{η: 5 η 5 -C 5 Me 4 -SiMe 2 CH 2 CHdCHCH 2 SiMe 2 C 5 Me 4 }] (X ) Cl, 12; OMe, 13). Oxidation of 8 with PbCl 2 yields η 1 -alkenyl complex [TiCl{η 1 :η: 5 η 5 -C 5 Me 4 SiMe 2 CH(Ti)CHdCHCH 2 SiMe 2 C 5 Me 4 }] (11). A similar oxidation of 12 to ansa-titanocene dichloride [TiCl 2 {η: 5 η 5 -C 5 Me 4 SiMe 2 CHCHdCHCH 2 -SiMe 2 C 5 Me 4 }] (14) containing a symmetrical unsaturated bridging chain requires a stronger oxidizing agent, AgCl. Compounds 5, 7, 8, and 10-14 have been characterized by X-ray crystallography.

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“…A similar conclusion is arrived at in the crystal structure of (PhC 5 Me 4 ) 2 TiCl 2 (32) (Figure 8). 74 Bis 2-methylbenz[e]indenyltitanium dichloride (34) (Scheme 15) is also prepared largely by way of route 3 (see section II.A.1). 77 Physical properties and references for titanocenes containing a bulky functionalized group are listed in Table 6.…”

Section: Bis-cp(ind) Titanium Compounds Containing a Bulky Group In Tmentioning

confidence: 99%

“…74 Single-crystal [3-CMe 2 Ph-η 5 -C 5 H 3 Me] 2 TiCl 2 (33) suitable for X-ray diffraction was recrystallized from toluene and presented in Figure 7. The molecule is C 2 -symmetric with a tetrahedral geometry around the central titanium atom formed by the centroids of the Cp rings and the two chlorine atoms.…”

Section: Bis-cp(ind) Titanium Compounds Containing a Bulky Group In Tmentioning

confidence: 99%

Synthesis, Structures, and Catalytic Reactions of Ring-Substituted Titanium(IV) Complexes

et al. 2003

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Syntheses and Crystal Structures of Dichlorobis[tetramethyl(phenyl)cyclopentadienyl]titanium(IV) and Chlorobis[tetramethyl(phenyl)cyclopentadienyl]titanium(III)

Cited by 20 publications

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Effect of the Trimethylsilyl Substituent on the Reactivity of Permethyltitanocene

Effect of the Trimethylsilyl Substituent on the Reactivity of Permethyltitanocene

Reduction-Induced Cyclization and Redox Reactions of Fully Methylated Titanocene Dichlorides Bearing Pendant Alkenyldimethylsilyl Groups, [TiCl₂{η⁵-C₅Me₄(SiMe₂R)}₂] (R = Vinyl and Allyl)

Synthesis, Structures, and Catalytic Reactions of Ring-Substituted Titanium(IV) Complexes

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Syntheses and Crystal Structures of Dichlorobis[tetramethyl(phenyl)cyclopentadienyl]titanium(IV) and Chlorobis[tetramethyl(phenyl)cyclopentadienyl]titanium(III)

Cited by 20 publications

References 0 publications

Effect of the Trimethylsilyl Substituent on the Reactivity of Permethyltitanocene

Effect of the Trimethylsilyl Substituent on the Reactivity of Permethyltitanocene

Reduction-Induced Cyclization and Redox Reactions of Fully Methylated Titanocene Dichlorides Bearing Pendant Alkenyldimethylsilyl Groups, [TiCl2{η5-C5Me4(SiMe2R)}2] (R = Vinyl and Allyl)

Synthesis, Structures, and Catalytic Reactions of Ring-Substituted Titanium(IV) Complexes

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Reduction-Induced Cyclization and Redox Reactions of Fully Methylated Titanocene Dichlorides Bearing Pendant Alkenyldimethylsilyl Groups, [TiCl₂{η⁵-C₅Me₄(SiMe₂R)}₂] (R = Vinyl and Allyl)