Synthesis and structure of lithium amides and solvated derivatives containing bulky bis(silylamide) ligands

Tang, Yongbai; Zakharov, Lev N.; Rheingold, Arnold L.; Kemp, Richard A.

doi:10.1016/j.poly.2005.05.006

Cited by 14 publications

(5 citation statements)

References 59 publications

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“…The rearranged anion is characterized by the C(7)–C(8), C(7)–N(1), C(18)–C(19), and C(18)–N(2) bond distances in each ligand, which are 1.377(5), 1.344(4), 1.369(5), and 1.331(5) Å, respectively. The K–N bond distances lie in the longer range of 2.830(3) and 3.038(3) Å for K(1)–N(1) and K(2)–N(2), respectively, in comparison to other potassium–amide complexes [(Me 3 Si) 2 NK] (2.770(3), 2.803(3) Å), [(Me 2 t BuSi)(Me 2 Si)NK] 2 (2.764(1), 2.784(1) Å), and [(TMEDA)K(TMP)] 2 (range of 2.744(2)–2.836(2) Å). Examining the orientation of C(9)–N(1)–C(7)–C(8) and C(19)–N(2)–C(17)–C(18), the aza-enolate moiety with respect to the propyl group is strictly planar, reflecting the inclusion of the N atom in delocalization.…”

Section: Resultsmentioning

confidence: 97%

Anion Rearrangements of Alkali Metal Complexes of the Chiral Amine (S)-N-α-(Methylbenzyl)phenylallylamine: Structural and Solution Insights

et al. 2012

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Reaction of the chiral amine (S)-N-α-(methylbenzyl)phenylallylamine, [(S)-N-α-mbpa], with nBuM (M = Li, Na, K) in the presence of the Lewis donors TMEDA or THF (TMEDA = N,N,N′,N′-tetramethylethylenediamine, THF = tetrahydrofuran) resulted in a series of mono-or dimetalated complexes, [{PhC(H)CH 3 NC(H)C-(H)C(H)PhLi 2 (TMEDA) 2 ] 1, [{PhC(H)CH 3 NCH CHCH 2 PhNa(TMEDA)] 2 2, and [PhC(CH 2 )N-(CH 2 CH 2 CH 3 )K] ∞ 3, being formed with various 1,3sigmatropic rearranged allylic bonding patterns. Completing previous work on the related amine N-α-(methylbenzyl)allylamine, the potassiated aza-enolate complex [(R)-{(PhC(CH 2 )N(CH 2 CH 2 CH 3 (THF)] ∞ 4 is also reported. All four complexes 1−4 have been characterized by single-crystal X-ray diffraction and solution NMR spectroscopy studies. DTF calculations on model systems investigated the preference for the monomeric Li 2 -mbpa 1 to undergo isomerization to the aza-allyl anion conformation, which, interestingly, is more energetically stable as a monomeric complex.

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Section: Resultsmentioning

confidence: 97%

Anion Rearrangements of Alkali Metal Complexes of the Chiral Amine (S)-N-α-(Methylbenzyl)phenylallylamine: Structural and Solution Insights

et al. 2012

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“…A fascinating array of solid-state structures is possible by slightly modifying the electronic and steric properties of the amido ligand. For instance, in the absence of donor solvent, dimers, [54][55][56][57][58][59][60] trimers, [61][62][63][64][65][66] tetramers, [67,68] hexamers, [69] and polymers [70] of lithium secondary amides can be isolated. As expected the introduction of a donor solvent generally decreases the aggregation state to form smaller aggregates.…”

Section: Introductionmentioning

confidence: 99%

A Structural and Computational Study of Synthetically Important Alkali‐Metal/Tetramethylpiperidide (TMP) Amine Solvates

Armstrong

Graham

Kennedy

et al. 2008

Chemistry A European J

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Two heavy alkali-metal salts of the sterically demanding amine, 2,2,6,6-tetramethylpiperidine (TMPH), have been prepared using different methodologies. Complex 1, [((tmeda)Na(tmp))2] (TMEDA=N,N, N',N'-tetramethylethylenediamine), can be synthesized by a deprotonative route. This is achieved by reacting butylsodium with TMPH in the presence of excess TMEDA in hexane. The potassium congener [((tmeda)K(tmp))2] (2), can be prepared by treating KTMP (made using a metathesis reaction between LiTMP and potassium tert-butoxide) with an excess of TMEDA in hexane. In the solid state, 1 and 2 are essentially isostructural. They are discretely dimeric and their framework consists of a four-membered M-N-M-N ring (M=Na or K, N=TMP). Due to the high steric demand of the TMP ligand, the TMEDA molecules bind to the metal centers in an asymmetric manner. In 2, each of the coordination spheres of the metals is completed by an agostic K...CH3(TMP) interaction. DFT calculations at the B3 LYP/6-311G** level give an insight into why 1 and 2 adopt dramatically different structures from their previously reported, "open-dimeric", lithium counterpart. The theoretical work also focuses on the TMEDA-free parent amide complexes and reveals that the energy difference for the formation of [(M(tmp))x] (in which, M=Li or Na, x=3 or 4; and M=K, x=2, 3 or 4) are small.

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“…A lithium salt of this amide, Li 2 [μ-N(SiMe 2 Ph) 2 ] 2 , has been structurally characterized, and iron, copper, gallium, and tin derivatives have been made. Since in synthetic f element chemistry, lithium readily forms “ate” salt adducts, , sodium and potassium precursors are often preferred. We report here the synthesis and structural characterization of potassium and sodium salts of the [N(SiMe 2 Ph) 2 ] 1- ligand as well as the first f element complex of this silylamide.…”

Section: Introductionmentioning

confidence: 99%

Lanthanum and Alkali Metal Coordination Chemistry of the Bis(dimethylphenylsilyl)amide Ligand

2006

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The coordination chemistry of the bis(dimethylphenylsilyl)amide ligand, [N(SiMe2Ph)2]1-, with sodium, potassium, and lanthanum has been investigated for comparison with the more commonly used [N(SiMe3)2]1- and [N(SiHMe2)2]1- ligands. HN(SiMe2Ph)2 reacts with KH to produce KN(SiMe2Ph)2, 1, which crystallizes from toluene as the dimer [KN(SiMe2Ph)2(C7H8)]2, 2. The structure of 2 shows that the [N(SiMe2Ph)2]1- ligand can function as a polyhapto ligand with coordination from each phenyl group as well as the normal nitrogen ligation and agostic methyl interactions common in methylsilylamides. Each potassium in 2 is ligated by an eta4-toluene, two bridging nitrogen atoms, and an eta2-phenyl, an eta1-phenyl, and an eta1-methyl group. KN(SiMe2Ph)2 crystallizes from toluene in the presence of 18-crown-6 to make the monometallic complex (18-crown-6)KN(SiMe2Ph)2, 3, in which [N(SiMe2Ph)2]1- functions as a simple monodentate ligand through nitrogen. The reaction of HN(SiMe2Ph)2 with NaH in THF at reflux for 2 days generates Na[N(SiMe2Ph)2], 4, which crystallizes as the solvated dimer {(THF)Na[mu-eta1:eta1-N(SiMe2Ph)2]}2, 5. A lanthanide metallocene derivative of [N(SiMe2Ph)2]1- was obtained by reaction of K[N(SiMe2Ph)2] with [(C5Me5)2La][(mu-Ph)2BPh2]. Crystals of (C5Me5)2La[N(SiMe2Ph)2], 6, show agostic interactions between lanthanum and methyl groups of each silyl substituent. The [N(SiMe3)2]1- analogue of 3, (18-crown-6)KN(SiMe3)2, 7, was also structurally characterized for comparison.

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Synthesis and structure of lithium amides and solvated derivatives containing bulky bis(silylamide) ligands

Cited by 14 publications

References 59 publications

Anion Rearrangements of Alkali Metal Complexes of the Chiral Amine (S)-N-α-(Methylbenzyl)phenylallylamine: Structural and Solution Insights

Anion Rearrangements of Alkali Metal Complexes of the Chiral Amine (S)-N-α-(Methylbenzyl)phenylallylamine: Structural and Solution Insights

A Structural and Computational Study of Synthetically Important Alkali‐Metal/Tetramethylpiperidide (TMP) Amine Solvates

Lanthanum and Alkali Metal Coordination Chemistry of the Bis(dimethylphenylsilyl)amide Ligand

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