Silyl-, Germyl-, and Stannyl-Substituted Group 6 Pentacarbonyl Metalates

Wagner, Harald; Baumgartner, Judith; Marschner, Christoph

doi:10.1021/om0503747

Cited by 26 publications

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References 32 publications

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“…In close analogy, the Si2−W bond of 2.6594(4) Å is also long in comparison to previously published examples (2.34–2.67 Å) [21,22,25] . Moreover, it is in the range of Si−W single bond lengths (2.69 Å mean) measured in silanide complexes, for example [(SiMe 3 ) 3 Si−W(CO) 5 ] − [26] …”

Section: Resultssupporting

confidence: 80%

“…[21,22,25] Moreover, it is in the range of SiÀ W single bond lengths (2.69 Å mean) measured in silanide complexes, for example [(SiMe 3 ) 3 SiÀ W(CO) 5 ] À . [26] The 13 C NMR spectra of 5 a,b revealed two signals for the five carbonyl atoms, due to the axial and equatorial positions of the carbonyl groups. All other resonances have also been assigned and can be found in the Experimental Section.…”

Section: Resultsmentioning

confidence: 97%

“…[ 21 , 22 , 25 ] Moreover, it is in the range of Si−W single bond lengths (2.69 Å mean) measured in silanide complexes, for example [(SiMe 3 ) 3 Si−W(CO) 5 ] − . [26] …”

Section: Resultsmentioning

confidence: 99%

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An NHC‐Mediated Metal‐Free Approach towards an NHC‐Coordinated Endocyclic Disilene

et al. 2022

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A convenient metal‐free approach towards an N‐heterocyclic carbene (NHC)‐coordinated disilene 2 is described. Compound 2 , featuring the disilene incorporated in cyclopolysilane framework, was obtained in good yield and characterized using NMR spectroscopy and X‐ray crystallography. Density functional theory (DFT) calculations of the reaction mechanism provide a rationale for the observed reactivity and give detailed information on the bonding situation of the base‐stabilized disilene. Compound 2 undergoes thermal or light‐ induced (λ=456 nm) NHC loss, and a dimerization process to give a corresponding dimer with a Si 10 skeleton. In order to shed light on the dimerization mechanism, DFT calculations were performed. Moreover, the reactivity of 2 was examined with selected examples of transition metal carbonyl compounds.

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Section: Resultssupporting

confidence: 80%

Section: Resultsmentioning

confidence: 97%

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An NHC‐Mediated Metal‐Free Approach towards an NHC‐Coordinated Endocyclic Disilene

et al. 2022

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“…16 indicating only weak electrostatic interactions between the silyl anion and the metal cation in M-3. A structural comparison of the rare-earth with the alkaline earth derivatives M-3 reveals striking similarities (Table 1) To elucidate the donor ability of the "naked" silyl anions, Yb-3 was reacted with BPh 3 , a medium Lewis acid 17 , and W(CO) 6 , known to undergo substitution reactions with loss of CO. [18][19][20] In fact, the reaction with of two equivalents of BPh 3 in THF resulted in the formation of a micro-crystalline precipitate identified by multi-nuclei NMR spectroscopy and elemental analysis as The solid-state structure of Yb-4 was confirmed by singlecrystal X-ray crystallography; suitable crystals were grown from THF at room temperature (Figure 2). Yb-4 contains two molecules of non-coordinating THF; crystalline samples which had been exposed to vacuum for ca.…”

Section: Scheme 1 Design Of Hetero-bimetallic Zwitterionsmentioning

confidence: 99%

Synthesis, Structure, and Reactivity of Zwitterionic Divalent Rare-Earth Metal Silanides

et al. 2015

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ABSTRACT:The synthesis and structures of the first zwitterionic divalent rare-earth metal silanides of the formula [Si(SiMe 2 OMe) 3 - 3 ] 2 M, (M-3), where M = Eu, Yb, Sm, is reported. M-3 compounds feature spirocyclic bicyclooctane structures in which the central rare-earth metal ions are being octahedrally coordinated by six methoxy groups. Zwitterionic silanides are an emerging class of donorsubstituted silyl anions 1, 2 that are potentially useful as ambidentate ligands to support main group and transition metals.3-10 Interest in these types of highly reactive zwitterions primarily arises from the "naked" silyl anion that is rigidly locked and insulated from the metal cation by internal donor bridges. Unlike tetracoordinate borate-based zwitterions 11 , zwitterionic silanides are tri-coordinated and consequently contain a stereochemically active electron pair localized at the silyl anion, which behaves as a Lewis base that can bind to electrophilic transition and main group metal centers (Scheme 1). Scheme 1. Design of hetero-bimetallic zwitterions.In this regard, we recently reported the synthesis and discrete structures of zwitterionic alkali metal silanides of the formula [Si(SiMe 2 OCH 2 CH 2 OMe) 3 - 6 ]M (M = Li, Na, K) and demonstrated that the charge separated, "naked" silyl anion is available for additional metal binding, allowing for the synthesis of novel zwitterionic hetero-bimetallic silanides. 6,8 In addition, we succeeded in synthesizing and structurally characterizing novel zwitterionic alkaline earth metal silanides of formula [Si(SiMe 2 OMe) 3 - 3 ] 2 M (M = Mg, Ca, Sr, Ba). These discrete homoleptic complexes represent the first examples of metalcontaining zwitterions that are composed of two "naked" silyl anions.7 On the other hand, zwitterionic silanides of the rare-earth metals regardless of their oxidation state have not been prepared so far. Herein, we report on the synthesis and structures of the first zwitterionic divalent europium, ytterbium and samarium silanides and the reaction behavior of the divalent ytterbium silanide toward BPh 3 and W(CO) 6 (1), with commercially or synthetically readily available metal alkoxides, M(OR) 2 (M = Ca, Sr, Ba) in tetrahydrofuran (THF) as the solvent (Scheme 2).7 Owing to their zwitterionic nature, M-3 compounds proved to be poorly soluble, even in THF, and precipitated from the reaction mixture as crystalline materials, which greatly facilitated their isolation and purification. For the synthesis of the zwitterionic divalent rare earth silanides M-3 (M = Eu, Yb, Sm), assumed to be of low solubility similar to that of their alkaline earth counterparts, salt metathesis as an alternative route was envisioned because of the lack of commercially available divalent rare-earth alkoxides. , generated upon standing at room temperature for several hours crystalline precipitates of the europium, ytterbium and samarium silanides, M-3, in acceptable isolated yields (Scheme 2). The use of lithium silanide, Li-2, as the nucleophile was crucial to the isola...

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“…The preparation of compounds with bonds between a transition metal and either silicon, germanium, tin or lead has provided a rich chemistry including synthetic and structural aspects as well as catalytic applications. [133][134][135][136][137][138][139][140][141][142][143][144][145][146][147] Furthermore, the investigation of the reactivity of divalent heavier Group 14 elements has prompted a constant interest due to the wide range of reaction possibilities. [78,79,81,83,86,87] The presence of bulky ligands and the complexation with transition metals greatly increase the stability of otherwise unstable species.…”

Section: Oh Functionality Of Germanium(ii) Compounds For the Formatio...mentioning

confidence: 99%

Germanium-, Tin-, Lead-, and Bismuth-Containing <i>β</i>-Diketiminato Complexes for the Synthesis and Structural Characterization of Hydroxide, Carboxylic Acid, Heterobimetallic Oxide, Transition Metal-Main Group, Hydride and Halide Compounds

William¹

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tris(bis(trimethylsilyl)methyl)phenyl). It was noted that the sterically demanding Tbt groups effectively surround the reactive Bi−Bi double bond moiety suppressing oligomerization. [5] Interestingly, a stable bicyclic compound with two Si=Si double bonds, a silicon analogue of spiropentadiene, resulted from the reaction of R 3 SiSiBr 2 Cl (R = tBuMe 2 Si) and potassium graphite at low temperature. [6] In contrast, the parent spiropentadiene decomposes within a few minutes in solution and its composition has only been confirmed by NMR spectroscopy and by analyses of a few chemical-trapping reactions. [7,8] The long-sought and quite reactive form. [19] However, a revision of this statement by using DFT calculations revealed that the sterically demanding group forces a trans-bent equilibrium structure as the lowest lying energy minimum. [20] It is worth emphasizing that the reactivity of heavier Group 14 alkyne analogues (Ge, Sn) was investigated with conjugated dienes or small molecules. It was postulated in the case of ArGeGeAr (Ar = 2,6-Trip 2 C 6 H 3 ; Trip = 2,4,6-iPr 3 C 6 H 2 ) which did not give the expected cycloadduct when reacted with 2,3-dimethyl-1,3-butadiene due to its biradical character, a feature which also accounts for the products obtained between digermyne and small molecules (e.g. H 2 , N 2 O, O 2 , N 3 SiMe 3 , PhCCPh, P 4 , S 8 and others). [21,22] However, it is notable that the digermyne BbtGeGeBbt (Bbt = 2,6-Me(SiMe 3 ) 2 -4-Me(SiMe 3 ) 3 -C 6 H 2 ) even in the presence of H 2 0, 2,3-dimethyl-1,3-butadiene, and Et 3 SiH, the latter compound known to be very reactive toward radical, showed no biradical character, but rather addition product formation with the former reagents and no reaction at all with Et 3 SiH. [23] As for distannyne, formation of {Sn(Ar)(μ-OH)} 2 is observed by reacting either N 2 O or TEMPO (tetramethylpiperidineoxide) with ArSnSnAr (Ar = 2,6-Dip 2 C 6 H 3 ; Dip = 2,6-iPr 2 C 6 H 3 ). [24] Of direct relevance in the present context are the contribution of other bulky monodentate alkoxide, aryloxide, diorganoamide (−NR 2 ) and alkyl (−CH(SiMe 3 ) 2 ) ligands in the stabilization of low-coordinate germanium, tin, and lead compounds. And of particular interest are the Lappert´s amides M{N(SiMe 3 ) 2 } 2 (M = Ge, Sn, Pb), which remain two coordinate in the solid and behave in solution as a two electron donor analogous to carbenes. [25][26][27][28] The chemistry of the β-diketiminato ligand since its initial recognition as an ancillary ligand and the effective stabilization of lower oxidation states and lower coordination numbers has experienced a burgeoning due to the steric and electronic properties and a variety of coordination modes. [29] The ligand can be regarded as a bidentate and monoanionic ligand and can be prepared by direct condensation of 2,4-pentanedion, 2,6-diisopropylaniline, and HCl in boiling ethanol and subsequent neutralization of the generated ligand hydrochloride with Na 2 CO 3 to obtain free LH (Scheme 1). [30,31] Remarkable progress in the stabili...

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Silyl-, Germyl-, and Stannyl-Substituted Group 6 Pentacarbonyl Metalates

Cited by 26 publications

References 32 publications

An NHC‐Mediated Metal‐Free Approach towards an NHC‐Coordinated Endocyclic Disilene

An NHC‐Mediated Metal‐Free Approach towards an NHC‐Coordinated Endocyclic Disilene

Synthesis, Structure, and Reactivity of Zwitterionic Divalent Rare-Earth Metal Silanides

Germanium-, Tin-, Lead-, and Bismuth-Containing <i>β</i>-Diketiminato Complexes for the Synthesis and Structural Characterization of Hydroxide, Carboxylic Acid, Heterobimetallic Oxide, Transition Metal-Main Group, Hydride and Halide Compounds

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