Methylenedimagnesium dibromide as precursor of metal carbene complexes; preparation of titanacyclobutanes.

BRUIN, J. W.; Schat, G.; Akkerman, Otto S.; Bickelhaupt, F.

doi:10.1016/s0040-4039(00)94319-3

Cited by 32 publications

(6 citation statements)

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“…0.15 Å shorter than those in related compounds with ''normal'' σ-bonds between zirconium() and sp 3 [21] ). Even the ZrϪC bond in [Cp 2 Zr(µ-η 1 ,η 2 -Me 3 SiCCPh)(µ-Cl)AlMe 2 ], in which an sp 2 -hybridized carbon is σ-bonded to zirconium, is slightly longer [2.186 (3) Å ].…”

Section: Reactions Of Me 3 Sich(mgbr) 2 (8)mentioning

confidence: 79%

“…The Zr···H distances [2.496(7) and 2.546(7) Å ] are more than 1 Å shorter than the sum of their contact radii, and 1 J C,H ϭ 91.4 Hz is small, though in the upper range for sp 3 -hybridized agostic systems (60Ϫ90 Hz).…”

Section: And 12ј (Loose Interaction Of [Cp 2 Zrϭchsime 3 ] With the Lmentioning

confidence: 99%

“…[1,2] We have reported the synthesis of 3, [3,4] the magnesium analogue of 1, from bis(bromomagnesio)methane (2) [3,5Ϫ9] and titanocene dichloride. The chemistry of 2 and of other 1,1-di-Grignard reagents has been reviewed.…”

Section: Introductionmentioning

confidence: 99%

“…[10Ϫ13] Like 1 or related 1,1-bismetal-substituted reagents, 3 reacts with alkenes or alkynes to give titanacyclobutanes (4) or titanacyclobutenes (5), respectively (Scheme 2). [3] Reaction with trimethylphosphane yields the carbene complex 6. [14] Of special interest here is the elimination of magnesium halide from 3 by evaporation of an ethereal solution followed by dissolution in toluene, which gave, based on its analytical data, MgBr 2 (CH 2 TiCp 2 ) 2 which was tentatively formulated as the spiro-organomagnesium compound 7.…”

Section: Introductionmentioning

confidence: 99%

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Investigations on the Reactivity of Bis(bromomagnesio)trimethylsilylmethane − Molecular Structure of a Tebbe‐Type Spiro‐Organomagnesium Compound

et al. 2004

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The reactivity of the 1,1‐di‐Grignard reagent Me3SiCH(MgBr)2 (8) towards transition metal dihalides has been investigated. While most transformations were sluggish and gave no well‐defined products, the reaction of 8 with [Cp2ZrCl2] in a 1:1 ratio gave, in low yield, the novel spiro‐organomagnesium compound [Cp2ZrCHSiMe3(μ‐Br)]2Mg (12), which is stable at room temperature and does not disproportionate on addition of dioxane. An X‐ray crystal structure determination has shown that, in the solid state, 12 is present as the C2 symmetric stereoisomer 12a; it is sterically very crowded due to the trimethylsilyl substituents. Partial metalla‐alkene character is indicated by the short zirconium−carbon bonds, and agostic zirconium−hydrogen interactions by the short zirconium−hydrogen distances (Zr···H−C) and small 1JC,H coupling constants. In benzene solution, equilibrium between 12a and its C1 symmetric stereoisomer 12b was detected by 1H and 13C NMR spectroscopy. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)

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Section: Reactions Of Me 3 Sich(mgbr) 2 (8)mentioning

confidence: 79%

Section: And 12ј (Loose Interaction Of [Cp 2 Zrϭchsime 3 ] With the Lmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Investigations on the Reactivity of Bis(bromomagnesio)trimethylsilylmethane − Molecular Structure of a Tebbe‐Type Spiro‐Organomagnesium Compound

et al. 2004

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“…This article is © 2006 John Wiley & Sons, Ltd. This article was originally published in the Encyclopedia of Inorganic Chemistry in 2006 by John Wiley & Sons, Ltd. DOI: 10.1002/9781119951438.eibc0230a manner similar to that of Tebbe's reagent 34. Metal alkylidene complexes (see Schrock-type Carbene Complexes) have been proposed as intermediates in many catalytic reactions, including alkene metathesis (see Organic Synthesis Using Metal-mediated Metathesis Reactions), alkene and alkyne polymerization, methylenation of carbonyl compounds, and cyclopropanation of alkenes [35][36][37][38][39].…”

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confidence: 97%

Titanium: Organometallic Chemistry

Mintz

2005

Encyclopedia of Inorganic and Bioinorganic Chemistry

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The majority of titanium organometallic chemistry involves complexes in which the titanium is in its highest oxidation state (+4) with cyclopentadienyl derivatives as ancillary ligands. However, considerable chemistry has also been developed for complexes with titanium in the +3 and +2 oxidation state, with lesser amounts of chemistry developed for titanium in lower oxidation states (+1, 0). Since the early 1980s, chemists have placed considerable emphasis on the fine‐tuning of the structure and reactivity of titanium organometallic complexes. Particular emphasis has been devoted to tailoring the structure and reactivity of bis(cyclopentadienyl)titanium derivatives by incorporating electron‐donating, electron‐withdrawing, sterically demanding, or chiral substituents on the cyclopentadienyl ring. Considerable effort has gone into preparing ansa‐metallocenes with a wide variety of bridging groups and substituents to fine‐tune the reactivity catalysts prepared from them. In a similar manner, considerable effort has gone into the development of constrained geometry complexes. Several types of chiral substituted cyclopentadienyl, annulated cyclopentadienyl, ansa ‐metallocenes, and constrained geometry complexes have been prepared and applied to olefin polymerization and organic synthesis. Additional efforts at modifying the structure and reactivity by focusing on varying the oxidation state or coordination geometry at the titanium center have expanded over the past decade.

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Bis(cyclopentadienyl)-3,3-dimethyltitanacyclobutane

Straus

2001

Encyclopedia of Reagents for Organic Synthesis

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Methylenedimagnesium dibromide as precursor of metal carbene complexes; preparation of titanacyclobutanes.

Cited by 32 publications

References 11 publications

Investigations on the Reactivity of Bis(bromomagnesio)trimethylsilylmethane − Molecular Structure of a Tebbe‐Type Spiro‐Organomagnesium Compound

Investigations on the Reactivity of Bis(bromomagnesio)trimethylsilylmethane − Molecular Structure of a Tebbe‐Type Spiro‐Organomagnesium Compound

Titanium: Organometallic Chemistry

Bis(cyclopentadienyl)-3,3-dimethyltitanacyclobutane

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