Synthesis, characterization and thermal behaviour of four homoleptic titanium silanolates

Mansfeld, Dirk; Schürmann, Markus; Mehring, M.

doi:10.1002/aoc.967

Cited by 10 publications

(10 citation statements)

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“…The observed weight loss (1 39.8 %; 2 27.6 %; 22 ]. [10] Similarly, the powder X-ray data of the decomposition products 2b and 3b were also indicative of Bi 12 SiO 20 (JCPDS No. 76-726) as major crystalline material.…”

Section: Resultsmentioning

confidence: 93%

Structural Relationships in High‐Nuclearity Heterobimetallic Bismuth‐Oxo Clusters

2005

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Section: Resultsmentioning

confidence: 93%

Structural Relationships in High‐Nuclearity Heterobimetallic Bismuth‐Oxo Clusters

2005

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“…A bismuth siloxide that seemed suitable for such a study is the monomer [Bi(OSiMe 2 t Bu) 3 ] described by Mehring and co-workers …”

Section: Resultsmentioning

confidence: 99%

“…Solvents were purified, dried, and degassed prior to use. [Cp 2 MoH 2 ], [(η 5 -Cp)Mo(μ 2 -η 5 :η 1 -C 5 H 4 )Bi] 2 , [Bi(OSiMe 2 t Bu) 3 ], and [Bi(OSiPh 3 ) 3 (thf) 3 ] were prepared according to the literature procedures.…”

Section: Methodsmentioning

confidence: 99%

Opening of Bent Bi−C Bonds by Silanols To Give Stable Cp₂Mo(μ-BiOR)₂MoCp₂Complexes

2008

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First, the reactivity of molybdocene dihydride toward bismuth siloxides was studied. Depending on the stoichiometry, compounds of the type [Cp2Mo{Bi(OR)2}2] (R = SiMe2 t Bu, 1, R = SiPh3, 3) or [Cp2Mo(μ-BiOR)2MoCp2] (R = SiMe2 t Bu, 2 t , R = SiPh3, 4 t ) were obtained. Apart from 4 all of these compounds were characterized via single-crystal X-ray diffraction analyses, which revealed for the compound 2 t a trans orientation of the two silanolate groups, similar to that found in case of the corresponding tert-butoxide derivatives. In contrast to those, however, the silanolates 2 t and 4 t proved to be stable in solution with respect to subsequent intramolecular silanol eliminations, which allowed for detailed NMR spectroscopic investigation. These studies revealed that on dissolution of 2 t and 4 t , they slowly enter into an equilibrium with isomers containing the two silanolate ligands in a cis configuration, 2 c and 4 c . However, the cis isomers cannot be isolated from the isomeric mixtures, as the trans isomer always precipitates first. Due to the thermodynamic stability of 2 and 4, these complexes can also be obtained starting from [(η5-Cp)Mo(μ2-η5:η1-C5H4)Bi]2, which contains bent Bi−C bonds and is formed from the tert-butoxide derivative of 2 and 4, [Cp2Mo{Bi(O t Bu)}2MoCp2], II H , by further alcohol elimination as the thermodynamically most favored product in that system: Reacting this compound with the silanols HOSiMe2 t Bu and HOSiPh3 provides 2 t and 4 t , respectively, which underlines that these complexes represent the thermodynamic holes within these corresponding systems.

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“…Notably, the analogous siloxide complex Ti[OSi i Pr 3 ] 4 has previously been reported by Mansfeld and co-workers. 23 The 1 H nuclear magnetic resonance (NMR) spectrum of 1 in benzene-d 6 contains resonances at 1.34 and 1.56 ppm for the CH 3 and CH groups, respectively. Similarly, the solution 13…”

Section: ■ Resultsmentioning

confidence: 99%

Titanium–Germoxy Precursor Route to Germanium-Modified Epoxidation Catalysts with Enhanced Activity

et al. 2013

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The complex Ti[OGe i Pr 3 ] 4 (1), prepared via the reaction of Ti(O i Pr) 4 with i Pr 3 GeOH, represents a useful structural and spectroscopic model for titanium−germanium species dispersed onto silica. This precursor was used to introduce site-isolated Ti(IV) centers onto the surface of a mesoporous SBA15 support via the thermolytic molecular precursor method. The local environments of the supported materials (TiGe 3 SBA15 and calcined TiGe 3 SBA15-O 2 ) were studied by various spectroscopic methods, including X-ray absorption spectroscopy. These materials are active catalysts for the epoxidation of cyclic and terminal olefins with alkyl hydroperoxides under anhydrous conditions. Compared to catalysts synthesized from siloxide-only precursors, the new catalysts produce 2−3 times more product after 9 h under identical reaction conditions for the epoxidations of cyclohexene and 1-octene. The new materials did not significantly leach under reaction conditions.

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Synthesis, characterization and thermal behaviour of four homoleptic titanium silanolates

Cited by 10 publications

References 29 publications

Structural Relationships in High‐Nuclearity Heterobimetallic Bismuth‐Oxo Clusters

Structural Relationships in High‐Nuclearity Heterobimetallic Bismuth‐Oxo Clusters

Opening of Bent Bi−C Bonds by Silanols To Give Stable Cp₂Mo(μ-BiOR)₂MoCp₂Complexes

Titanium–Germoxy Precursor Route to Germanium-Modified Epoxidation Catalysts with Enhanced Activity

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Synthesis, characterization and thermal behaviour of four homoleptic titanium silanolates

Cited by 10 publications

References 29 publications

Structural Relationships in High‐Nuclearity Heterobimetallic Bismuth‐Oxo Clusters

Structural Relationships in High‐Nuclearity Heterobimetallic Bismuth‐Oxo Clusters

Opening of Bent Bi−C Bonds by Silanols To Give Stable Cp2Mo(μ-BiOR)2MoCp2Complexes

Titanium–Germoxy Precursor Route to Germanium-Modified Epoxidation Catalysts with Enhanced Activity

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Opening of Bent Bi−C Bonds by Silanols To Give Stable Cp₂Mo(μ-BiOR)₂MoCp₂Complexes