Direct Synthesis of Heterometallic Europium/Barium Complexes: H2[Eu2Ba6O2(OiPr)16(THF)4] and EuBa2(OC6H4Me-4)7(diglyme)2(DME)

Evans, William J.; Giarikos, Dimitrios G.; Greci, Michael A.; Ziller, Joseph W.

doi:10.1002/1099-0682(20022)2002:2<453::aid-ejic453>3.0.co;2-4

Cited by 24 publications

(12 citation statements)

References 31 publications

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“…In contrast, precatalyst loadings above 3.3 mol % induced an approximately linear reduction in reaction rate with increasing [Ba] (Figures S9, S10). Similar effects have previously been observed in Ae‐catalyzed aminoalkene hydroamination and may be attributed to the formation of higher molecularity barium alkoxide aggregates at increased barium concentration …”

Section: Resultssupporting

confidence: 82%

Heavier Alkaline‐Earth Catalyzed Dehydrocoupling of Silanes and Alcohols for the Synthesis of Metallo‐Polysilylethers

Morris

Hill

Mahon

et al. 2020

Chemistry A European J

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The dehydrocoupling of silanes and alcohols mediated by heavier alkaline‐earth catalysts, [Ae{N(SiMe3)2}2⋅(THF)2] (I–III) and [Ae{CH(SiMe3)2}2⋅(THF)2], (IV–VI) (Ae=Ca, Sr, Ba) is described. Primary, secondary, and tertiary alcohols were coupled to phenylsilane or diphenylsilane, whereas tertiary silanes are less tolerant towards bulky substrates. Some control over reaction selectivity towards mono‐, di‐, or tri‐substituted silylether products was achieved through alteration of reaction stoichiometry, conditions, and catalyst. The ferrocenyl silylether, FeCp(C5H4SiPh(OBn)2) (2), was prepared and fully characterized from the ferrocenylsilane, FeCp(C5H4SiPhH2) (1), and benzyl alcohol using barium catalysis. Stoichiometric experiments suggested a reaction manifold involving the formation of Ae–alkoxide and hydride species, and a series of dimeric Ae–alkoxides [(Ph3CO)Ae(μ2‐OCPh3)Ae(THF)] (3 a–c, Ae=Ca, Sr, Ba) were isolated and fully characterized. Mechanistic experiments suggested a complex reaction mechanism involving dimeric or polynuclear active species, whose kinetics are highly dependent on variables such as the identity and concentration of the precatalyst, silane, and alcohol. Turnover frequencies increase on descending Group 2 of the periodic table, with the barium precatalyst III displaying an apparent first‐order dependence in both silane and alcohol, and an optimum catalyst loading of 3 mol % Ba, above which activity decreases. With precatalyst III in THF, ferrocene‐containing poly‐ and oligosilylethers with ferrocene pendent to‐ (P1–P4) or as a constituent (P5, P6) of the main polymer chain were prepared from 1 or Fe(C5H4SiPhH2)2 (4) with diols 1,4‐(HOCH2)2‐(C6H4) and 1,4‐(CH(CH3)OH)2‐(C6H4), respectively. The resultant materials were characterized by NMR spectroscopy, gel permeation chromatography (GPC) and DOSY NMR spectroscopy, with estimated molecular weights in excess of 20,000 Da for P1 and P4. The iron centers display reversible redox behavior and thermal analysis showed P1 and P5 to be promising precursors to magnetic ceramic materials.

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Section: Resultssupporting

confidence: 82%

Heavier Alkaline‐Earth Catalyzed Dehydrocoupling of Silanes and Alcohols for the Synthesis of Metallo‐Polysilylethers

Morris

Hill

Mahon

et al. 2020

Chemistry A European J

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“…In the compound presented by Evans, Giarikos et al (2002;CSD refcode BAFVEK), BVS = 2.88 v.u. (for R Eu III-O = 2.038 Å ; Trzesowska et al, 2004).…”

Section: Application Of Bvmmentioning

confidence: 99%

Bond-valence parameters of lanthanides

Trzesowska

Kruszyński

Bartczak

2006

Acta Crystallogr B Struct Sci

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Ln-O and Ln-N bond-valence parameters have been computed in coordination complexes for lanthanides (Ln) at oxidation states other than +3 (Ce(IV), Sm(II), Eu(II) and Yb(II)). Moreover, Ln-Cl, Ln-S and Ln-C(pi-bonded) bond-valence parameters are presented, as calculated for coordination compounds. In general, the bond-valence parameters decrease in the order Ln-O > Ln-C > Ln-N > Ln-Cl > Ln-S. It has been found that the values of bond-valence parameters decrease with increasing lanthanide atomic number for coordination compounds. As expected, the values of lanthanide-oxygen and lanthanide-nitrogen bond-valence parameters diminish with increasing lanthanide oxidation state. Several examples are given where the total valence of the lanthanide ion is apparently incorrectly assigned, as well as cases where bond-valence method calculations confirm the doubtful oxidation state assignment.

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“…An added benefit is that no air‐sensitive reagents need to be prepared. The simple structural frameworks and homoleptic nature of heterobimetallic complexes 1 – 18 contrast with previously reported solvated aryloxo rare earth–alkaline earth heterobimetallic complexes, such as [H 2 Ba 2 Sr 6 (hmpa) 6 (μ 5 ‐O 2 )(OPh) 14 ] (hmpa=hexamethylphosphoramide),23a [H 2 Eu 2 Ba 6 (μ 5 ‐O 2 )(O i Pr) 16 (thf) 4 ]23b and [EuBa 2 Sr 6 (dig) 2 (dme)(OAr 1 ) 7 ] (OAr 1 =4‐methylphenolate, dig=diglyme, dme=1,2‐dimethoxyethane,23b and the solvated alkali metal–alkaline earth and alkali metal–rare earth mixed metal cages [MM′(OPh) 8 (thf) 6 ] (M=Ca, Sr, Ba, Sm, Eu; M′=Li, Na) 24…”

Section: Resultsmentioning

confidence: 81%

Charge‐Separated and Molecular Heterobimetallic Rare Earth–Rare Earth and Alkaline Earth–Rare Earth Aryloxo Complexes Featuring Intramolecular Metal–π‐arene Interactions

Deacon

Junk

Moxey

et al. 2009

Chemistry A European J

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Treatment of a rare earth metal (Ln) and a potential divalent rare earth metal (Ln') or an alkaline earth metal (Ae) with 2,6-diphenylphenol (HOdpp) at elevated temperatures (200-250 degrees C) afforded heterobimetallic aryloxo complexes, which were structurally characterised. A charge-separated species [(Ln'/Ae)(2)(Odpp)(3)][Ln(Odpp)(4)] was obtained for a range of metals, demonstrating the similarities between the chemistry of the divalent rare earth metals and the alkaline earth metals. The [(Ln'/Ae)(2)(Odpp)(3)](+) cation in the heterobimetallic structures is unusual in that it consists solely of bridging aryloxide ligands. A molecular heterobimetallic species [AeEu(Odpp)(4)] (Ae = Ca, Sr, Ba) was obtained by treating an alkaline earth metal and Eu metal with HOdpp at elevated temperatures. Similarly, [BaSr(Odpp)(4)] was prepared by treating Ba metal and Sr metal with HOdpp. Treatment of [Ba(2)(Odpp)(4)] with [Mg(Odpp)(2)(thf)(2)] in toluene afforded [Ba(2)(Odpp)(3)][Mg(Odpp)(3)(thf)]. Analogous solution-based syntheses were not possible for [(Ln'/Ae)(2)(Odpp)(3)][Ln(Odpp)(4)] complexes, for which the free-metal route was essential. As a result of the absence of additional donor ligands, the crystal structures of the heterobimetallic complexes feature extensive pi-Ph-metal interactions involving the pendant phenyl groups of the Odpp ligands, thus enabling the large electropositive metal atoms to attain coordination saturation. The charge-separated heterobimetallic species were purified by extraction with toluene/thf mixtures at ambient temperature (Ba-containing compounds) or by extraction with toluene under pressure above the boiling point of the solvent (other products). In donor solvents, heterobimetallic complexes other than those containing barium were found to fragment into homometallic species.

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Direct Synthesis of Heterometallic Europium/Barium Complexes: H2[Eu2Ba6O2(OiPr)16(THF)4] and EuBa2(OC6H4Me-4)7(diglyme)2(DME)

Cited by 24 publications

References 31 publications

Heavier Alkaline‐Earth Catalyzed Dehydrocoupling of Silanes and Alcohols for the Synthesis of Metallo‐Polysilylethers

Heavier Alkaline‐Earth Catalyzed Dehydrocoupling of Silanes and Alcohols for the Synthesis of Metallo‐Polysilylethers

Bond-valence parameters of lanthanides

Charge‐Separated and Molecular Heterobimetallic Rare Earth–Rare Earth and Alkaline Earth–Rare Earth Aryloxo Complexes Featuring Intramolecular Metal–π‐arene Interactions

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