New Formulas for Zincate Chemistry: Synergistic Effect and Synthetic Applications of Hetero-bimetal Ate Complexes

Uchiyama, Masanobu; Wang, Chao

doi:10.1007/3418_2013_72

Cited by 23 publications

(4 citation statements)

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“…On comparison of the molecular structures of 4 and 5 , it could be tempting to describe 4 as a premetalation complex of 5 ; however, it should be noted that 4 is a stable species that does not evolve to 5 even under forcing reaction conditions (70 °C, 12 h), which makes this assumption very unlikely. This highlights the importance of the synthetic methods employed and the remarkable differences that can be realized in bimetallic chemistry by having the two metals operate in either a stepwise or synchronous manner …”

Section: Resultsmentioning

confidence: 99%

“…Over the past decade the chemistry of s-block heterobimetallic (ate) reagents, which combine metals of markedly different polarities, has developed at a remarkable pace, with the realization of their synergic chemical profiles, which cannot be replicated by their single-metal components . When cooperative effects are switched on, these ates, usually made by pairing an alkali metal with either Mg or Zn, can display enhanced reactivities, unique selectivities, and superior functional group tolerance to traditional polar organometallic reagents such as organolithium and Grignard reagents .…”

Section: Introductionmentioning

confidence: 99%

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Accessing Sodium Ferrate Complexes Containing Neutral and Anionic N-Heterocyclic Carbene Ligands: Structural, Synthetic, and Magnetic Insights

et al. 2015

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This study reports the synthesis and single-crystal X-ray crystallographic, NMR spectroscopic, and magnetic characterization of a series of sodium ferrates using bis(amide) Fe(HMDS)2 as a precursor (HMDS = 1,1,1,3,3,3-hexamethyldisilazide). Reaction with sodium reagents NaHMDS and NaCH2SiMe3 in hexane afforded donor-solvent-free sodium ferrates [{NaFe(HMDS)3}∞] (1) and [{NaFe(HMDS)2(CH2SiMe3)}∞] (2), respectively, which exhibit contacted ion pair structures, giving rise to new polymeric chain arrangements made up of a combination of inter- and intramolecular Na···Me(HMDS) electrostatic interactions. Addition of the unsaturated NHC IPr (IPr = 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene) to 1 and 2 caused deaggregation of their polymeric structures to form discrete NHC-stabilized solvent-separated ion pairs [Na(IPr)2](+)[Fe(HMDS)3](-) (3) and [(THF)3·NaIPr](+)[Fe(HMDS)2CH2SiMe3](-) (4), where in both cases, the NHC ligand coordinates preferentially to Na. In contrast, when IPr is sequentially reacted with the single-metal reagents NaCH2SiMe3 and Fe(HMDS)2, the novel heteroleptic ferrate (THF)3Na[:C{[N(2,6-(i)Pr2C6H3)]2CHCFe(HMDS)2}] (5) is obtained. This contains an anionic NHC ligand acting as an unsymmetrical bridge between the two metals, coordinating through its abnormal C4 position to Fe and its normal C2 position to Na. The formation of 5 can be described as an indirect ferration process where IPr is first metalated at the C4 position by the polar sodium alkyl reagent, which in turn undergoes transmetalation to the more electronegative Fe(HMDS)2 fragment. Treatment of 5 with 1 molar equiv of methyl triflate (MeOTf) led to the isolation and structural elucidation of the neutral abnormal NHC (aNHC) tricoordinate iron complex [CH3C{[N(2,6-iPr2C6H3)]2CHCFe(HMDS)2}] (6) with the subsequent elimination of NaOTf, disclosing the selectivity of complex 5 to react with this electrophile via its C2 position, leaving its Fe-C4 and Fe-N bonds intact. The magnetic susceptibility properties of compounds 1-6 have been examined. This study revealed a drastic change of magnetic susceptibility in replacing a pure σ donor from an idealized trigonal coordination environment by an NHC π donating character.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Accessing Sodium Ferrate Complexes Containing Neutral and Anionic N-Heterocyclic Carbene Ligands: Structural, Synthetic, and Magnetic Insights

et al. 2015

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“…Furthermore, Sn-Li reagent prepared by this method allowed us to introduce a stannyl group into the final product with excellent yield and high atom-efficiency (Scheme -I). When the present method was combined with zincate chemistry, the stannyl zincate reacted smoothly with phenylacetylene in 1:1 ratio in the presence of a catalytic amount of CuCl at 0 °C to give the adduct in high yield (Scheme -II), in sharp contrast to the traditional protocols for stannylzincation. , …”

mentioning

confidence: 94%

Stannyl-Lithium: A Facile and Efficient Synthesis Facilitating Further Applications

Wang

Uchiyama

2015

J. Am. Chem. Soc.

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We have developed a highly efficient, practical, polycyclic aromatic hydrocarbon (PAH)-catalyzed synthesis of stannyl lithium (Sn-Li), in which the tin resource (stannyl chloride or distannyl) is rapidly and quantitatively transformed into Sn-Li reagent at room temperature without formation of any (toxic) byproducts. The resulting Sn-Li reagent can be stored at ambient temperature for months and shows high reactivity toward various substrates, with quantitative atom efficiency.

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“…[1][2][3][4][5][6] This interest is primarily due to the fact that the mixed metal species can often perform chemistry, which is unobtainable by the monometallic constituent parts, or can be utilized at more user-friendly reaction temperatures and in the presence of donor solvents or reactive functional groups. TMP-ate complexes (where TMP is 2,2,6,6tetramethylpiperidide), particularly magnesiate [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24] and zincate reagents [25][26][27][28][29][30] are amongst the most widely studied. Focusing on TMP-zincate systems, several donor-solvated heterobimetal-lic formulations have been crystallographically-characterized including (TMEDA)•Li(μ-TMP)(μ-n Bu)Zn( n Bu), 31 (TMEDA)•Li-(μ-TMP)Zn(Me) 2 , 32 (THF)•Li(μ-TMP)Zn( t Bu) 2 , 30,[33][34][35] (TMEDA)• Na(μ-TMP)(μ-CH 2 SiMe 3 )Zn(CH 2 SiMe 3 ) 36 and most pertinent to this study (TMEDA)•Na(μ-TMP)(μ-t Bu)Zn( t Bu) 1.…”

Section: Introductionmentioning

confidence: 99%

Synthetic and reactivity studies of hetero-tri-anionic sodium zincates

2016

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The synthesis and characterisation of several sodium zincate complexes are reported. The all-alkyl monomeric sodium zincate, (PMEDTA)·Na(μ-CH2SiMe3)Zn(t)Bu22, is prepared by combining equimolar quantities of (t)Bu2Zn, (n)BuNa and PMDETA (N,N,N',N'',N''-pentamethyldiethylenetriamine)]. A similar approach was used to prepare and isolate the unusual dimeric zincate [(PMEDTA)·Na(μ-(n)Bu)Zn(t)Bu2]23. When an equimolar mixture of (n)BuNa, (t)Bu2Zn and TMP(H) (2,2,6,6-tetramethylpiperidine) is combined in hexane, the hetero-tri-leptic TMP(H)-solvated zincate (TMPH)Na(μ-TMP)(μ-(n)Bu)Zn(t)Bu 4 results. Complex 4 can also be prepared using a rational approach [i.e., utilising two molar equivalents of TMP(H)]. When TMEDA is reacted with an equimolar mixture of (n)BuNa, (t)Bu2Zn and TMP(H), the monomeric sodium zincate (TMEDA)Na(μ-TMP)(μ-(n)Bu)Zn(t)Bu 5 was obtained - this complex is structurally similar to the synthetically useful relation (TMEDA)·Na(μ-TMP)(μ-(t)Bu)Zn((t)Bu) 1. By changing the sodium reagent used in the synthesis of 5, it was possible to prepare (TMEDA)Na(μ-TMP)(μ-Me3SiCH2)Zn(t)Bu 6. By reacting 5 with cis-DMP(H) (cis-2,6-dimethylpiperidine), the zincate could thermodynamically function as an amide base, to give the transamination product (TMEDA)Na(μ-cis-DMP)(μ-(n)Bu)Zn(t)Bu 7, although no crystals could be grown. However, when HMDS(H) (1,1,1,3,3,3-hexamethyldisilazane) or PEA(H) [(+)-bis[(R)-1-phenylethyl]amine] is reacted with 5, crystalline (TMEDA)Na(μ-HMDS)(μ-(n)Bu)Zn(t)Bu 8 or (TMEDA)Na(μ-PEA)(μ-(n)Bu)Zn(t)Bu 9 is isolated respectively. With PNA(H) (N-phenylnaphthalen-1-amine) the reaction took a different course and resulted in the formation of the dimeric sodium amide complex [(TMEDA)Na(PNA)]210. When reacted with benzene, it appears that a TMEDA-free variant of 5 functions thermodynamically as an (n)Bu base to yield the previously reported (TMEDA)Na(μ-TMP)((t)Bu)Zn(μ-C6H4)Zn((t)Bu)(μ-TMP)Na(TMEDA) 11. Finally when reacted with TEMPO (2,2,6,6-tetramethylpiperidinyloxy), 5 undergoes a single electron transfer reaction to form (TMEDA)Na(μ-TMP)(μ-TEMPO)Zn(n)Bu 12.

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New Formulas for Zincate Chemistry: Synergistic Effect and Synthetic Applications of Hetero-bimetal Ate Complexes

Cited by 23 publications

References 98 publications

Accessing Sodium Ferrate Complexes Containing Neutral and Anionic N-Heterocyclic Carbene Ligands: Structural, Synthetic, and Magnetic Insights

Accessing Sodium Ferrate Complexes Containing Neutral and Anionic N-Heterocyclic Carbene Ligands: Structural, Synthetic, and Magnetic Insights

Stannyl-Lithium: A Facile and Efficient Synthesis Facilitating Further Applications

Synthetic and reactivity studies of hetero-tri-anionic sodium zincates

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