Some co-ordination complexes of dimethyl- and diphenyl-magnesium with ethers and amines

Coates, G. E.; Heslop, J. A.

doi:10.1039/j19660000026

Cited by 21 publications

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“…This intermediate, instead of dimerizing with the loss of methane, undergoes a disproportionation reaction to give II and a dialkylmagnesium compound (see Scheme ) through a Schlenk-type of equilibrium, as shown in eq 2 The postulated (Me) 2 Mg(TMEDA) product was reported to be soluble in benzene and would remain in solution when II was recrystallized from that solvent …”

Section: Resultsmentioning

confidence: 99%

“…The formation of the exo-sandwich magnesacarborane instead of a more conventional closo-product, similar to I , could be the result of less steric crowding in the initially formed closo- methylmagnesacarborane intermediate, which in turn would allow dimerization directly between the two capping magnesium atoms via a double Me and carborane bridge. Such doubly bridged structures have been proposed as transition states in the ligand exchange processes that proceed through Schlenk equilibria . In the formation of I , the presence of the second bulky SiMe 3 group could prevent such bridging and restrict interaction of the two methylmagnesacarborane intermediates to the sides opposite the cage carbons as found in I (see Figure ).…”

Section: Resultsmentioning

confidence: 99%

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Chemistry ofC-Trimethylsilyl-Substituted Heterocarboranes. 23. Synthetic, Spectroscopic, and Structural Investigation on Half- and Full-Sandwich Magnesacarboranes of 2,3- and 2,4-C₂B₄Carborane Ligands

et al. 1998

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The reaction of nido-1-Na(L) n -2-(SiMe3)-3-(R)-2,3-C2B4H5 (n = 2, L = THF, R = SiMe3; n = 1, L = TMEDA, R = SiMe3 or Me) or closo-exo-5,6-[(μ-H)2Li(L) n ]-1-Li(L) n -2,4-(SiMe3)2-2,4-C2B4H4 (n = 2, L = THF; n = 1, L = TMEDA) with various magnesium reagents produced a number of different magnesacarboranes. The product of a 1:1 molar ratio reaction of the 2,3-C2B4 monosodium compound (R = SiMe3 and L = TMEDA) with MeMgBr was the half-sandwich magnesacarborane closo-1-Mg(TMEDA)-2,3-(SiMe3)2-2,3-C2B4H4 (I), while when R = Me, the same reaction conditions gave the novel full-exo-sandwich complex commo-exo-4,4‘,5,5‘-Mg(TMEDA)[2-(SiMe3)-3-(Me)-2,3-C2B4H5]2 (II). The full-endo-sandwich magnesacarboranes [Na(THF)2]2[commo-1,1‘-Mg{2,3-(SiMe3)2-2,3-C2B4H4}2] (IV) and [Na(TMEDA)]2[commo-1,1‘-Mg{2,3-(SiMe3)2-2,3-C2B4H4}2] (V) were the exclusive products when the appropriate monosodium compound reacted with Mg(Bu)2 in 2:1 molar ratios. Reaction of closo-exo-5,6-[(μ-H)2Li(TMEDA)]-1-Li(TMEDA)-2,4-(SiMe3)2-2,4-C2B4H4 with MgBr2 in a 1:1 molar ratio produced closo-1-Mg(TMEDA)-2,4-(SiMe3)2-2,4-C2B4H4 (III), while a 2:1 molar ratio gave [Li(TMEDA)2]2[commo-1,1‘-Mg{2,4-(SiMe3)2-2,4-C2B4H4}2] (VI). The yields ranged from 73% for III to 94% for II. On the other hand, the 1:1 molar ratio reaction of the THF-solvated 2,4-C2B4 disodium compound with MeMgBr, followed by the addition of 1 equiv of the THF-solvated monosodium compound of the 2,3-C2B4 carborane did not give the expected mixed-ligand complex but produced a 50:50 mixture of IV and [Li(THF)2]2[commo-1,1‘-Mg{2,4-(SiMe3)2-2,4-C2B4H4}2] (VII) in nearly quantitative yields. The magnesacarboranes were characterized by their infrared spectra, chemical analysis, H1, 11B, and 13C NMR spectra, and, in the case of VII, by its 7Li NMR spectrum. Compounds I, II, and IV were further characterized by single-crystal X-ray analysis. Compound I crystallizes as a dimer in which a Mg occupies the apical position above the pentagonal face of one carborane and is bonded to the unique boron of the other carborane in the dimer through a Mg−H−B bridge. The structure of II is one in which a TMEDA-solvated Mg is exo-polyhedrally bonded to two 2,3-C2B4 monoanionic ligands through a pair of Mg−H−B bridges, while in IV, the two carborane dianions are η5-bonded to a Mg in a more conventional endo-sandwich complex. The reactions with MeMgBr are thought to proceed through the formation of a methylmagnesacarborane intermediate which undergoes further reaction to give the final products. The 11B NMR spectra of I−VII were analyzed with the aid of ab initio GIAO molecular orbital calculations.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Chemistry ofC-Trimethylsilyl-Substituted Heterocarboranes. 23. Synthetic, Spectroscopic, and Structural Investigation on Half- and Full-Sandwich Magnesacarboranes of 2,3- and 2,4-C₂B₄Carborane Ligands

et al. 1998

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“…Elemental analysis was performed on aThermo Flash 2000 CHNS analyzer. 1a , 1b , 1c , 2a , , 2c , 3a , (TMEDA)MgMe 2 , Y(CH 2 SiMe 3 ) 3 (THF) 2 , and Zr(CH 2 SiMe 3 ) 4 were prepared according to literature methods.…”

Section: Methodsmentioning

confidence: 99%

Synthesis of Bis(amino)pyridines by the Stepwise Alkylation of Bis(imino)pyridines: An Unexpected and Selective Alkylation of the Aminoiminopyridine by AlMe₃

et al. 2011

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Bis(imino)pyridines 2-[2,6-(R 1 ) 2 C 6 H 3 NC(CH 3 )]-6-[2,6-(R 2 ) 2 C 6 H 3 NC(CH 3 )](C 5 H 3 N) (1a, R 1 = R 2 = i-Pr; 1b, R 1 = i-Pr, R 2 = CH 3 ; 1c, R 1 = R 2 = CH 3 ) were first alkylated by AlMe 3 and then hydrolyzed to aminoiminopyridines 2-[2,6-(R 1 ) 2 C 6 H 3 NC(CH 3 )]-6-[2,6-(R 2 ) 2 C 6 H 3 NHC(CH 3 ) 2 ](C 5 H 3 N) (3a, R 1 = R 2 = i-Pr; 3b, R 1 = i-Pr, R 2 = CH 3 ; 3c, R 1 = R 2 = CH 3 ). When the aminoiminopyridines were treated with AlMe 3 , the expected methane elimination was not found; alkylation at the imine functional group led to the aluminum complexes {2-[2,6-(R 1 ) 2 C 6 H 3 NC(CH 3 ) 2 ]-6-[2,6-(R 2 ) 2 C 6 H 3 NHC(CH 3 ) 2 ]-(C 5 H 3 N)}AlMe 2 (4a, R 1 = R 2 = i-Pr; 4b, R 1 = i-Pr, R 2 = CH 3 ; 4c, R 1 = R 2 = CH 3 ), which were further hydrolyzed to the bis(amino)pyridines 2-[2,6-(R 1 ) 2 C 6 H 3 NHC(CH 3 ) 2 ]-6-[2,6-(R 2 ) 2 C 6 H 3 NHC(CH 3 ) 2 ](C 5 H 3 N) (5a, R 1 = R 2 = i-Pr; 5b, R 1 = i-Pr, R 2 = CH 3 ; 5c, R 1 = R 2 = CH 3 ). The selective alkylation over elimination may come from the noninnocent property of the conjugated iminopyridine group. New magnesium, yttrium, and zirconium complexes supported by 5a ({2,6-[2,6-(i-(8)) were formed via the alkane elimination method.Since the first independent reports by Gibson, Bennett, and Brookhart that bis(imino)pyridine-supported iron and cobalt complexes were very active for olefin polymerization, 1 tremendous research has been undertaken to understand this efficient system. 2 Studies have shown that the conjugated ligand itself is noninnocent and is involved in a series of transformations such as deprotonation reactions, alkylation, and participation in redox reactions. 3,4 One of the transformations is the monoalkylation of the bis(imino)pyridine 1a to the aminoiminopyridine 3a by AlMe 3 via the aluminum complex 2a as the intermediate (Scheme 1). 3d,5 The aminoiminopyridine 3a has offered a platform to numerous complexes with unique properties and applications. 6 A further straightforward modification to the ligand framework is bis(amino)pyridine, in which both of the imine groups are replaced by amine donors. Bis(amino)pyridines exert quite different electronic and steric environments and have been applied as useful supporting ligands for transition metals which mainly have applications to polymer formation. 4,7,8 While the direct reduction of bis-(imino)pyridine to bis(amino)pyridine by sodium borohydride was previously reported, 9 this method cannot be applied to this ligand frame with bulky steric demands. The starting material was fully recovered when 1a was treated in the same way. Direct alkylation of 1a to bis(amino)pyridine 5a also does not work. 10 A general synthesis of bis(amino)pyridines was achieved by the substitution reaction of 2,6-bis(bromomethyl)-pyridine by amines. 11 We disclose here a convenient way to the bis(amino)pyridine 5 through selective alkylation of 3 by AlMe 3 followed by hydrolysis (Scheme 2). The expected formation of aluminum complex 2 from 3 via methane elimination was not found. ■ RESULT...

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“…The lithium benzamidinate complexes PhC(NSiMe 3 ) 2 Li(TMEDA) ( 1a ) and p -MePhC(NSiMe 3 ) 2 Li(TMEDA) ( 1b ), (TMEDA)Ni((acac) 2 ( 2 ), (TMEDA)MgMe 2 , and (TMEDA)NiMe 2 10d,32a were prepared according to the literature procedures.…”

Section: Methodsmentioning

confidence: 99%

Synthesis and Molecular Structures of Neutral Nickel Complexes. Catalytic Activity of (Benzamidinato)(acetylacetonato)nickel for the Addition Polymerization of Norbornene, the Oligomerization of Ethylene, and the Dimerization of Propylene

2005

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The new neutral nickel complexes PhC(NSiMe 3 ) 2 Ni(acac) (3), PhC(NSiMe 3 ) 2 Ni(acac)-(TMEDA) (4), [PhC(NSiMe 3 ) 2 ] 2 Ni 2 (5), [PhC(NSiMe 3 ) 2 ] 2 Ni‚Li 2 Br 2 (TMEDA) 2 ( 6), (TMEDA) 2 Ni (7), p-MePhC(NSiMe 3 ) 2 Ni(acac) (8), p-MePhC(NSiMe 3 ) 2 Ni(acac)(TMEDA) (9), [p-MePhC-(NSiMe 3 ) 2 ] 2 Ni (10), NiMe 2 Py 2 (11) and [p-MePhC(NSiMe 3 )] 2 Ni(Py) ( 14) have been synthesized and characterized. The solid-state molecular structures of all complexes have been confirmed by low-temperature X-ray diffraction analysis. The methyl complex p-MePhC(NSiMe 3 ) 2 Ni-(Me)(Py) ( 13) is not stable and rapidly decomposes, forming the complex [p-MePhC(NSiMe 3 )] 2 -Ni(Py) ( 14). Complex 3 activated with MAO has been shown to be an efficient catalytic system for the norbornene vinyl-type polymerization. The activity of the catalyst and the molecular weights of the resulting polynorbornenes were found to be dependent on the reaction time, the MAO/precatalyst ratio, and the reaction temperature. In addition, this catalytic system has been found to dimerize propylene to a mixture of hexenes with a high turnover frequency of η ) 9040 h -1 and oligomerize ethylene to either a mixture of C 4 -C 6 or/and C 4 -C 14 products, depending on the temperature and the solvent, extremely rapidly (η ) 83 500 h -1 ).

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Some co-ordination complexes of dimethyl- and diphenyl-magnesium with ethers and amines

Cited by 21 publications

References 0 publications

Chemistry ofC-Trimethylsilyl-Substituted Heterocarboranes. 23. Synthetic, Spectroscopic, and Structural Investigation on Half- and Full-Sandwich Magnesacarboranes of 2,3- and 2,4-C₂B₄Carborane Ligands

Chemistry ofC-Trimethylsilyl-Substituted Heterocarboranes. 23. Synthetic, Spectroscopic, and Structural Investigation on Half- and Full-Sandwich Magnesacarboranes of 2,3- and 2,4-C₂B₄Carborane Ligands

Synthesis of Bis(amino)pyridines by the Stepwise Alkylation of Bis(imino)pyridines: An Unexpected and Selective Alkylation of the Aminoiminopyridine by AlMe₃

Synthesis and Molecular Structures of Neutral Nickel Complexes. Catalytic Activity of (Benzamidinato)(acetylacetonato)nickel for the Addition Polymerization of Norbornene, the Oligomerization of Ethylene, and the Dimerization of Propylene

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Some co-ordination complexes of dimethyl- and diphenyl-magnesium with ethers and amines

Cited by 21 publications

References 0 publications

Chemistry ofC-Trimethylsilyl-Substituted Heterocarboranes. 23. Synthetic, Spectroscopic, and Structural Investigation on Half- and Full-Sandwich Magnesacarboranes of 2,3- and 2,4-C2B4Carborane Ligands

Chemistry ofC-Trimethylsilyl-Substituted Heterocarboranes. 23. Synthetic, Spectroscopic, and Structural Investigation on Half- and Full-Sandwich Magnesacarboranes of 2,3- and 2,4-C2B4Carborane Ligands

Synthesis of Bis(amino)pyridines by the Stepwise Alkylation of Bis(imino)pyridines: An Unexpected and Selective Alkylation of the Aminoiminopyridine by AlMe3

Synthesis and Molecular Structures of Neutral Nickel Complexes. Catalytic Activity of (Benzamidinato)(acetylacetonato)nickel for the Addition Polymerization of Norbornene, the Oligomerization of Ethylene, and the Dimerization of Propylene

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Chemistry ofC-Trimethylsilyl-Substituted Heterocarboranes. 23. Synthetic, Spectroscopic, and Structural Investigation on Half- and Full-Sandwich Magnesacarboranes of 2,3- and 2,4-C₂B₄Carborane Ligands

Chemistry ofC-Trimethylsilyl-Substituted Heterocarboranes. 23. Synthetic, Spectroscopic, and Structural Investigation on Half- and Full-Sandwich Magnesacarboranes of 2,3- and 2,4-C₂B₄Carborane Ligands

Synthesis of Bis(amino)pyridines by the Stepwise Alkylation of Bis(imino)pyridines: An Unexpected and Selective Alkylation of the Aminoiminopyridine by AlMe₃