Bifunctional and cyclic organomagnesium compounds

Spek, Anthony L.; Schat, G.; Holtkamp, H.C.; Blomberg, C.; Bickelhaupt, F.

doi:10.1016/s0022-328x(00)84408-3

Cited by 26 publications

(23 citation statements)

References 20 publications

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“…The C-Mg-C angle is 139.95 (9) ° and the O-Mg--O angle 89.47 (6) °. Similar bond angles were observed (Spek, Schat, Holtkamp, Blomberg & Bickelhaupt, 1977) (2) and 94.0 (2)°], species that also have Mg linked to two alkyl C atoms and two ether O atoms. It is possible that the ring structures have a significant influence on the C-Mg-C bond angle, particularly in the second of these structures.…”

supporting

confidence: 71%

(Dioxane)dineopentylmagnesium: a polymeric structure

Parvez¹,

Pajerski²,

Richey³

1988

Acta Crystallogr C

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supporting

confidence: 71%

(Dioxane)dineopentylmagnesium: a polymeric structure

Parvez¹,

Pajerski²,

Richey³

1988

Acta Crystallogr C

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“…7 After removal of magnesium halide, single crystals of 1 were grown. Due to rather large estimated standard deviations of the structural parameters determined by Bickelhaupt and co-workers at +20°C, 7 we redetermined the crystal structure at −140°C. These conditions allowed freely refining the positions of the hydrogen atoms.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…The synthesis was performed according to a literature procedure. 7 1,5-Dichloropentane (7.0 g, 50.0 mmol) was dropped into a suspension of 3.0 g (112.4 mmol) of magnesium turnings in 50 mL of THF. During this process the reaction flask was gently heated.…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

Synthesis, Crystal Structures, and Solution Behavior of Organomagnesium Derivatives of Alkane-1,4-diide as Well as -1,5-diide

et al. 2012

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The organomagnesium complexes [(thf) 2 Mg(μ-C 5 H 10 )] 2 (1), [(thf) 2 Mg(μ-C 4 H 8 )] ∞ (2), and [(thf) 2 Mg(μ-(C-(CH 3 ) 2 C 2 H 4 C(CH 3 ) 2 )] 2 (3) were prepared via direct synthesis from magnesium turnings and appropriate dichloroalkanes in tetrahydrofuran (THF). The aggregation degree in the solid state depends on the nature of the alkanediide. The THF solution of 3 shows a temperature-dependent equilibrium. The reactions of MgCl 2 (thf) 1.5 with 1,4-dilithiobutane yield the lithium magnesiates [Li(thf) 4 ] 2 [Mg 3 (C 4 H 8 ) 4 ] (4) and [{(tmeda)Li} 2 Mg(C 4 H 8 ) 2 ] (5) depending on the applied stoichiometry. The addition reaction of Ph 2 Mg(diox) (1,4-dioxane = diox) with 1,4-dilithiobutane leads to the formation of the heteroleptic magnesiate [{(tmeda)-Li} 2 MgPh 2 (C 4 H 8 )] (6), which shows in THF solution a ligand exchange (Schlenk-type) equilibrium with the homoleptic derivatives [{(thf) 2 Li} 2 Mg(C 4 H 8 ) 2 ] and [{(thf) 2 Li} 2 MgPh 4 ]. ■ INTRODUCTIONDianions are widely used reagents with a broad field of application in organic syntheses; however, common procedures avoid isolation and characterization of these intermediate derivatives. 1 As early as 1901 Tissier and Grignard reacted 1,2-dibromoethane with magnesium turnings in order to produce a vicinal di-Grignard reagent. 2 However, these reactions always proceeded with elimination of ethylene and formation of magnesium bromide. A few years later the reaction of 1,3-dibromopropane with magnesium yielded mainly cyclopropane in a Wurtz-type coupling reaction, but as a side reaction 1,6-hexanediyl-di(magnesium bromide) [hexamethylene di-(magnesium bromide)] was transferred into suberic acid (octanedioic acid) via 2-fold addition of carbon dioxide and water. 3 Generally, the direct synthesis of magnesium turnings with 1,ω-dihalogenated alkanes with more than three methylene units gave the corresponding di-Grignard reagents with high yields. However, the structures of these reagents remained unknown for a long time, and even in the recent textbook of Elschenbroich 4 these compounds were formulated as magnesiacycles, which resulted from a Schlenk-type equilibrium from BrMg-(CH 2 ) n+3 -MgBr (n = 1, 2, 3) after addition of dioxane (eq 1). Bickelhaupt and co-workers intensively investigated these magnesium 1,ω-alkanediides in solution and the solid state. 5 They proposed a monomer− dimer equilibrium in tetrahydrofuran for magnesiacyclohexane (eq 2) and a second Schlenk-type equilibrium for pentamethylene di(magnesium bromide) after addition of magnesium bromide (eq 1, n =2). 6 In the solid state, a centrosymmetric dimer of magnesiacyclohexane, 1,7-dimagnesiacyclododecane (Mg−C 213(1) and 215(1) pm), with very large C−Mg−C angles of 141.5(3)°was observed. 7 Bickelhaupt and co-workers explained the dimerization by entropic effects with the large C− Mg−C angle disfavoring small rings. On the contrary, magnesiacyclopentane (n = 1) was not detected in tetrahydrofuran solution, but this molecule completely dimerized to 1,6-dimagnesiacyclodecane. 8 In a...

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“…The structure determination of cyclic OMCs obtained through the above described procedure has demanded in due time heavy and near work [169,170]. a,x-Dimagnesium compounds were specifically converted into magnesacyclanes 131 with the aid of organomercury compounds [170][171][172].…”

Section: Thermal Methods To Synthesize Magnesacarbocyclesmentioning

confidence: 99%