A π-carbanion Grignard reagent

Johnson, C. W.; Toney, J.; Stucky, Galen D.

doi:10.1016/s0022-328x(00)86968-5

Cited by 40 publications

(10 citation statements)

References 20 publications

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“…--h3-HB(3-Bu'pz)3lMgX + Tl + dec. (13) above hypothesis was correct, then it would be necessary (39) We can not exclude the possibility that the solvated form of MgClj that is generated as a result of the Schlenk equilibrium may lead to higher concentrations of "MgCl2" existing in solutions of Grignard reagents than in their absence. (…”

Section: Resultsmentioning

confidence: 99%

[Tris(pyrazolyl)hydroborato]magnesium alkyl derivatives: synthetic and structural studies

Han¹,

Parkin²

1991

Organometallics

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A series of solvent-free, monomeric, (tris(pyrazolyl)hydroborato)magnesium alkyl derivatives, (i?3-HB-(3-Butpz)a}MgR and (ij3-HB(3,5-Me2pz)3)MgR (3-* = 3-C3N2Bu'H2; 3,5-Me2pz = 3,5-C3N2Me2H; R = CH3, CH2CH3, CH(CH3)2, C(CH3)3, CH2(CH2)2CH3, CH2Si(CH3)3, CH=CH2, C6H6), have been prepared by the reaction of the appropriate dialkylmagnesium compound with either the potassium or thallium derivatives of the respective tris(pyrazolyl)hydroborato ligand. The molecular structures of the complexes b3-HB(3-Bu^pz)3)MgCH3, !,)3-HB(3-Butpz)3|MgCH(CH3)2, and jj)3-HB(3,5-Me2pz)3|MgCH2Si(CH3)3 have been determined by X-ray diffraction, which shows that in each case the complexes are monomeric with 4-coordinate magnesium centers and ^-coordinate tris(pyrazolyl)hydroborato ligands. (tj3-HB(3-Bulpz)3|MgCH3 is orthorhombic, Pnma, a = 16.362 (4) Á, b = 15.920 (5) A, c = 9.824 (4) A, and Z -4. ¡ij3-HB(3-Butpz)3)MgCH(CH3)2 is orthorhombic, Pnma, a = 17.171 (2) A, b = 15.893 (7) A, c = 10.034 (3) A, and Z = 4. (??3-HB(3,5-Me2pz)3|MgCH2Si(CH3)3 is monoclinic, C2/c, a = 23.897 (8) A, b = 8.010 (2) A, c = 30.072 (8) A, and Z = 8. In contrast to the clean reactions of the thallium and potassium tris(pyrazolybhydroborato derivatives with R2Mg, the corresponding reactions with Grignard reagents are more complex as a result of competition between Mg-R and Mg-X bond metathesis. The product distribution is dependent upon both RMgX and the tris(pyrazolyl)hydroborato reagent. Thus, for the thallium complex Tl(7)3-HB(3-Butpz)3|, chloro and bromo Grignard reagents favor alkyl ligand metathesis and the formation of ¡ij3-HB(3-Butpz)3}MgX, whereas the iodo Grignard reagent CH3MgI favors halide ligand metathesis and the formation of j?73-HB(3-Butpz)3)MgCH3. However, the selectivity of these reactions with Grignard reagents may be altered by the use of the potassium reagent K|HB(3-Butpz)3|, and thus, primary and secondary Grignard reagents react with K|HB(3-Butpz)3) to give the alkyl derivatives )»;3-HB(3-Bu*pz)3)MgR as the principal products.

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Section: Resultsmentioning

confidence: 99%

[Tris(pyrazolyl)hydroborato]magnesium alkyl derivatives: synthetic and structural studies

Han¹,

Parkin²

1991

Organometallics

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“…Thus it appears that conversion of an M-C1 to an M-Br or M-I complex according to equation ( 7) is a general and facile reaction. 22), M = Zr, R = CH2SiMe,, X = Br, 78%…”

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confidence: 99%

Metallocene derivatives of early transition metals. Part 4. Chemistry of the complexes [M(η-C₅H₅)₂RR′][M = Ti, Zr, or Hf; R = CH₂M′Me₃(M′= C, Si, Ge, or Sn) or CH(SiMe₃)₂; R′= Cl or alkyl] and the X-ray structures of [Zr(η-C₅H₅)₂(CH₂M′Me₃)₂](M′= C or Si)

Jeffery¹,

Läppert²,

Luong-Thi³

et al. 1981

J. Chem. Soc., Dalton Trans.

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“…X-ray structural information on the known complexes of organomagnesium compounds, [7][8][9][10][11][12] with magnesium coordinated to aminic-type nitrogen atoms, was taken as the starting point for modelling the N-methylindole-ethylmagnesium bromide complex. In fact, the coordination process is believed to involve a marked pyramidalization of the N-methylindole nitrogen atom, with a corresponding partial loss of aromaticity.…”

Section: Theoretical Investigationmentioning

confidence: 99%

“…The whole structure of the EtMgBr(N-methylindole)(Et 2 O) complex was then fully optimized with the 3-21G* basis set. It has been demonstrated 8 that this basis provides a satisfactory description of equilibrium geometries for many halogenated compounds. As a check, we calculated the 3-21G* equilibrium geometry for the EtMgBr(Et 2 O) 2 complex.…”

Section: Theoretical Investigationmentioning

confidence: 99%

Rate enhancement of 1,3-dipolar cycloaddition ofN-methylindole: the singular role of Grignard reagents

Benincori¹,

Sannicolò²,

Trimarco³

et al. 1998

J. Phys. Org. Chem.

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The reactions of 2-N-methylindolyl and 2-and 3-benzo [b]thiophenyl anions with nitrile oxides and nitrilimines were performed in order to investigate whether the use of anionic dipolarophiles modifies a classical 1,3-dipolar cycloaddition. When lithium compounds were used as bases, the heterocyclic anions invariably acted as nucleophilic species; in contrast, when a Grignard reagent was employed, the N-methylindole gave cycloaddition products with an extraordinary rate enhancement. The hypothesis that N-methylindole and ethylmagnesium bromide give an adduct much more reactive than N-methylindole itself was supported by the results of a theoretical investigation. The structure and electron distribution of the adduct were determined by ab initio calculations and compared with those of known Grignard complexes with nitrogen ligands. The performance of different basis sets was tested. The quantum theory of atoms in molecules was used to determine atomic charges and to describe the nature of bonds in terms of the properties of the electron density at the bond critical points.

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A π-carbanion Grignard reagent

Cited by 40 publications

References 20 publications

[Tris(pyrazolyl)hydroborato]magnesium alkyl derivatives: synthetic and structural studies

[Tris(pyrazolyl)hydroborato]magnesium alkyl derivatives: synthetic and structural studies

Metallocene derivatives of early transition metals. Part 4. Chemistry of the complexes [M(η-C₅H₅)₂RR′][M = Ti, Zr, or Hf; R = CH₂M′Me₃(M′= C, Si, Ge, or Sn) or CH(SiMe₃)₂; R′= Cl or alkyl] and the X-ray structures of [Zr(η-C₅H₅)₂(CH₂M′Me₃)₂](M′= C or Si)

Rate enhancement of 1,3-dipolar cycloaddition ofN-methylindole: the singular role of Grignard reagents

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A π-carbanion Grignard reagent

Cited by 40 publications

References 20 publications

[Tris(pyrazolyl)hydroborato]magnesium alkyl derivatives: synthetic and structural studies

[Tris(pyrazolyl)hydroborato]magnesium alkyl derivatives: synthetic and structural studies

Metallocene derivatives of early transition metals. Part 4. Chemistry of the complexes [M(η-C5H5)2RR′][M = Ti, Zr, or Hf; R = CH2M′Me3(M′= C, Si, Ge, or Sn) or CH(SiMe3)2; R′= Cl or alkyl] and the X-ray structures of [Zr(η-C5H5)2(CH2M′Me3)2](M′= C or Si)

Rate enhancement of 1,3-dipolar cycloaddition ofN-methylindole: the singular role of Grignard reagents

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Metallocene derivatives of early transition metals. Part 4. Chemistry of the complexes [M(η-C₅H₅)₂RR′][M = Ti, Zr, or Hf; R = CH₂M′Me₃(M′= C, Si, Ge, or Sn) or CH(SiMe₃)₂; R′= Cl or alkyl] and the X-ray structures of [Zr(η-C₅H₅)₂(CH₂M′Me₃)₂](M′= C or Si)