Donor-stabilised molecular Mg/Al-bimetallic hydrides

Stuhl, Christoph; Katzenmayer, Markus M.; Maichle‐Mößmer, Cäcilia; Anwander, Reiner

doi:10.1039/c8dt03343a

Cited by 7 publications

(10 citation statements)

References 66 publications

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“…Much less is known of Ae metal complexes with the smallest aluminate anion AlH 4 – , which are expected to show lower solubilities. Fichtner et al reported the synthesis of Mg(AlH 4 ) 2 and Ca(AlH 4 ) 2 from the corresponding AeCl 2 and NaAlH 4 in ethereal solvents. , For Sr(AlH 4 ) 2 , only a ball-milling route has been documented . We prepared these aluminates using the salt metathesis route mixing AeCl 2 (Ae = Mg, Ca, or Sr) and NaAlH 4 in THF in a 1/2 ratio (Scheme ).…”

Section: Resultsmentioning

confidence: 99%

“…The crystal structure of Mg(AlH 4 ) 2 ·(THF) 4 is known and described as a complex in which both aluminate anions are bound to Mg 2+ in a H 3 Al-(μ-H)-Mg fashion (Figure a and Table ). The crystal structure of Ca(AlH 4 ) 2 ·(THF) 4 is reported to be isostructural but of very poor quality, and hydride positions are uncertain . A high-quality structure, including refined hydride positions, is shown in Figure b.…”

Section: Resultsmentioning

confidence: 99%

“…Crystal structures of (a) Mg(AlH 4 ) 2 ·(THF) 4 , (b) [Ca(AlH 4 ) 2 ·(THF) 4 ] 2 , and (c) Sr(AlH 4 ) 2 ·(THF) 5 . H atoms, except those of AlH 4 – , have been omitted for the sake of clarity.…”

Section: Resultsmentioning

confidence: 99%

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Alkaline Earth Metal Aluminates as Catalysts for Imine Hydrogenation

et al. 2020

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Alkaline earth (Ae) metal complexes with the alanate anion AlH 4 − have been prepared by salt metathesis between NaAlH 4 and AeCl 2 in THF and could be isolated as Mg(AlH 4 ) 2 •(THF) 4 , Ca(AlH 4 ) 2 •(THF) 4 , and Sr(AlH 4 ) 2 •(THF) 5 . The previously reported crystal structure of the Mg alanate complex shows bonding of AlH 4 − with one bridging hydride, H 3 Al-(μ-H)-Mg, while the Ca and Sr alanates show a combination of H 3 Al-(μ-H)-Ae and H 2 Al-(μ-H) 2 -Ae bridging. The heteroleptic βdiketiminate complexes ( DIPP BDI)Mg(AlH 4 )•THF and ( DIPP BDI)Ca(AlH 4 )•(THF) 2 have been prepared by reaction of the corresponding Ae hydride complexes with AlH 3 •(THF) 2 [ DIPP BDI = DIPP-NC(Me)C(H)C(Me)N-DIPP, where DIPP = 2,6diisopropylphenyl]. Crystal structures show H 2 Al-(μ-H) 2 -Ae bridging. The Ca complex decomposes at room temperature by reduction of the β-diketiminate anion. Density functional theory calculations (B3PW91/ def2tzvpp) show that the formation of Ae(AlH 4 ) 2 from AeH 2 and AlH 3 is exothermic by ΔH (kilocalories per mole): Be, −68.8; Mg, −66.1; Ca, −95.4; Sr, −100.9; Ba, −112.3. Calculations of NPA charges on LiAlH 4 and the Ae alanate complexes (Ae = Mg, Ca, or Sr) show that these are highly ionic salts in which the charge on AlH 4 − of approximately −0.95 is hardly dependent on the countercation. Compared to LiAlH 4 , the Ae alanates are very efficient catalysts for imine hydrogenation, clearly extending the substrate scope. In addition to aldimines RC(H)NR′ (R/R′ = Ph/tBu, tBu/tBu, nPr/tBu, or Ph/Ph), ketimine PhC(Me)NtBu could be reduced. The salt [Bu 4 N + ][AlH 4− ] is catalytically not active, which shows that the s-block metal is crucial. The highest activities were found for the heterobimetallic Ca and Sr alanates.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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Alkaline Earth Metal Aluminates as Catalysts for Imine Hydrogenation

et al. 2020

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“…The methyl in [Cp*Be(μ‐Me)YbCp* 2 ] is a linear bridge [99] . [Cp*Mg(HAlMe 3 )(thf) 2 ] is liable to Schlenk equilibrium [100] . The Ph 2 P‐functionalized heavier metallocenes form PtMe 2 adducts [57e] .…”

Section: Cp’ (Cpr/indr/flur) Complexesmentioning

confidence: 99%

“…[99] [Cp*Mg(HAlMe 3 )(thf) 2 ] is liable to Schlenk equilibrium. [100] The Ph 2 P-functionalized heavier metallocenes form PtMe 2 adducts. [57e] Cp* 2 Ca forms 1 : 1 adducts with Cp* 2 HfCl 2 and [(mesitylene)Cr(CO) 3 ].…”

Section: (B) Heterobimetallic Complexesmentioning

confidence: 99%

Cyclopentadienyl Complexes of the Alkaline Earths in Light of the Periodic Trends

Baguli

Mondal

Mandal

et al. 2021

Chemistry An Asian Journal

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The electron‐rich cyclopentadienyl and the analogous indenyl and fluorenyl ligands (collectively denoted here as Cp’) have been impactful in stabilizing electron‐deficient metal centers including the highly electropositive alkaline earths. Being in the s‐block, the group 2 metals follow a major periodic variation in their atomic and ionic properties which is reflected in those Cp’ compounds. This article presents an overview of this class of compounds for all the five metals from beryllium to barium (radium is excluded for its radioactivity), highlighting their systematic variation.

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Reactivity of a Neutral Yttrium(III) Trimethyl Complex toward Brønsted and Lewis Acids

Mortis,

Malzacher,

Maichle‐Mössmer

et al. 2024

Chemistry A European J

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The present study corroborates that the neutral tridentate N‐ligand trimethyl‐triazacyclononane (Me3TACN) qualifies as a versatile platform to study selective ligand exchange with rare‐earth‐metal alkyl complexes, herein [(Me3TACN)YMe3]. Treatment with Brønsted‐acidic bis(dimethylsilyl)amine, HN(SiHMe2)2, gave selectively the mono‐exchanged heteroleptic complex [(Me3TACN)YMe2{N(SiHMe2)2}]. Depending on the molecular ratio employed, the reaction of [(Me3TACN)YMe3] with AlMe3 resulted in the isolation/crystallization of [(Me3TACN)YMe2(AlMe4)] [1:1] or ion‐separated [(Me3TACN)YMe(AlMe4)][AlMe4] [1:2] and [(Me3TACN)YMe(AlMe4)][Al2Me7] [1:3]. Analogous reactions with the heavier group 13 methyls GaMe3 and InMe3 generated mixed methyl/tetramethylgallato complex [(Me3TACN)YMe2(GaMe4)] and ion‐separated [{(Me3TACN)YMe2}2{µ‐Me}][InMe4]. Finally, dimethylalane, HAlMe2, converted [(Me3TACN)YMe3] into heteroaluminate [(Me3TACN)Y(HAlMe3)3], representing an AlMe3‐supported, molecular yttrium trihydride complex. All compounds were investigated by single crystal X‐ray diffraction (SC‐XRD), homo‐ and heteronuclear (13C, 27Al, 89Y, 115In) NMR as well as IR spectroscopies and elemental analyses.

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Donor-stabilised molecular Mg/Al-bimetallic hydrides

Abstract: Low-molecular organometallic hydride complexes of the type [(do)xMg{(μ2-H)(AlMe3)}2] form in ethereal solvents and display inherent reactivity of existing magnesium hydrido bonding.

Cited by 7 publications

References 66 publications

Alkaline Earth Metal Aluminates as Catalysts for Imine Hydrogenation

Alkaline Earth Metal Aluminates as Catalysts for Imine Hydrogenation

Cyclopentadienyl Complexes of the Alkaline Earths in Light of the Periodic Trends

Reactivity of a Neutral Yttrium(III) Trimethyl Complex toward Brønsted and Lewis Acids

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