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A series of new pyrazolate and mixed pyrazolate/pyrazole magnesium complexes is described and their reactivity toward carbon dioxide is examined. The dimeric complex [Mg(pztBu,tBu)2]2 inserts CO2 instantly and quantitatively forming the tetrameric complex [Mg(CO2·pztBu,tBu)2]4 and monomeric donor‐stabilized [Mg(CO2·pztBu,tBu)2(thf)2]. Complexes of the type [Mgx(pzR,R)2x(HpzR,R)y]n (R = iPr, tBu) engage in similar insertion reactions involving dissociation of the carbamic acid HOOCpzR,R. Even solid polymeric derivatives [Mg(pzR,R)2]n (R = Me, H) react instantaneously and exhaustively with CO2, the resulting [Mg(CO2·pz)2]m featuring a CO2 capacity of 35.7 wt% (8.2 mmol g−1). All described magnesium pyrazolates display completely reversible CO2 uptake in solution and in the solid state, respectively, as monitored via VT 1H NMR and in situ FTIR spectroscopy as well as thermogravimetric analysis. Fluorinated [Mg2(pzCF3,CF3)4(thf)3] does not yield any isolable CO2 insertion product but exhibits the highest activity in the catalytic transformation of epoxides and CO2 to cyclic carbonates. [ABSTRACT FROM AUTHOR]

The present study corroborates that the neutral tridentate N‐ligand 1,4,7‐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. [ABSTRACT FROM AUTHOR]

Synthesis of primary lanthanide amides in the bis‐hydrotris(1‐pyrazolyl)borate ligand environment has been achieved. Salt metathesis of [Dy(Tp)2(OTf)] 1‐Dy (OTf=CF3SO3) with K(N′′) (N′′=N(SiMe3)2) in toluene yielded the [bis(silyl)]amide [Dy(Tp)2(N′′)] 2‐Dy. Complexes 1‐Ln and 2‐Ln were both used to access primary lanthanide amides, where either metathesis of 1‐Ln with K(NHArCF3) (ArCF3=C6H3(CF3)2‐3,5) or protonolysis of 2‐Ln with H2NArCF3 in toluene yielded [Ln(Tp)2(NHArCF3)] 3‐Ln (Ln=Y, Dy). The synthesis of parent amides was also attempted, but the metathesis of 1‐Y with NaNH2 yielded complicated reaction mixtures, but from which the dimeric parent amide [{Y(Tp)2(μ‐NH2)}2] 4‐Y and an 'ate'‐salt [{Y(Tp)2(μ2‐OTf)(μ3‐OTf)Na(THF)2}2] 5‐Y were isolated. Full characterisation data are presented for all complexes, including the structure determination. [ABSTRACT FROM AUTHOR]

Monomeric, divalent ytterbium primary amides TptBu,MeYb(NHR)(thf)x (R = C6H3iPr2-2,6 = AriPr = Dipp, C6H3(CF3)2-3,5 = ArCF3, SiPh3) supported by the bulky hydrotris(3-tBu-5-Me-pyrazolyl)borato scorpionate ligand are synthesized acccording to salt metathesis and protonolysis protocols, respectively. Yb(II) precursors comprise YbI2(thf)2, Yb[N(SiMe3)2]2(thf)2 and TptBu,MeYb[N(SiMe3)2]. Complexes TptBu,MeYb(NHR)(thf)x readily engage in donor (thf) exchange with nitrogen donors like DMAP (4-dimethylaminopyridine) and pyridine. Treatment of TptBu,MeYb(NHArCF3)(thf)2 with the Lewis acids AlMe3 and GaMe3 results in the heterobimetallic complexes TptBu,MeYb(NHArCF3)(MMe3) (M = Al, Ga). Reactions of TptBu,MeYb(NHR)(thf)x (R = AriPr, ArCF3) with the halogenating agents C2Cl6 and TeBr4 give access to trivalent complexes [TptBu,MeYb(NHR)(X)] (X = Cl, Br). The ytterbium(II) complexes under study display 171Yb NMR chemical shifts in the range 582 ppm for TptBu,MeYb(NHArCF3)(GaMe3) to 954 ppm for TptBu,MeYb(NHSiPh3)(dmap). The salt-metathesis route is also applicable for the synthesis of complexes TptBu,MeLn(NHAriPr)(thf) (Ln = Sm, Eu) and TptBu,MeYb(NHArMe) (ArMe = C6H3Me2-2,6). [ABSTRACT FROM AUTHOR]

Discrete lanthanide(III) isobutylaluminates Ln[N(SiMe3)2](HAliBu3)(AliBu4) (Ln = La, Pr, Nd) are obtained from Ln[N(SiMe3)2]3 and triisobutylaluminium (TIBA). Nd[N(SiMe3)2](HAliBu3)(AliBu4) reacts with crown ether to give the ion pair [Nd(18-c-6){N(SiMe3)2}(HAliBu3)][AliBu4], featuring a strong Nd–H interaction in the solid state. The equimolar reaction of La[N(SiMe3)2](HAliBu3)(AliBu4) with fluorene resulted in the concomitant formation of [(μ-fluorenyl)3La2(μ-H)(HAliBu3)2] and (fluorenyl)2La[N(SiMe3)2]. [(μ-Fluorenyl)3La2(μ-H)(HAliBu3)2] features fluorenyl ligands with a μ-η6:η6 coordination around the hydrido-bridged dilanthanum core motif. The reported complexes are the first crystallographically characterized, ancillary ligand-free lanthanide(III) tetraisobutylaluminates, and display potential model systems for Ziegler-type polymerization catalysis. [ABSTRACT FROM AUTHOR]

Me3TACN (1,4,7‐trimethyl‐1,4,7‐triazacyclononane)‐stabilized trimethylytterbium was obtained via a salt‐metathesis protocol employing [(Me3TACN)YbCl3] and methyllithium. Complex [(Me3TACN)YbMe3] seems not to engage in redox chemistry with potassium graphite and is thermally quite stable in the solid state. Treatment of trivalent [(Me3TACN)YbMe3] with 3 equiv. of AlMe3 afforded divalent tetramethylaluminate complex [(Me3TACN)Yb(AlMe4)2]. The reaction of [(Me3TACN)YbMe3] with GaMe3 in THF gave trivalent ion pair [(Me3TACN)YbMe2(thf)][GaMe4], which is susceptible to reduction with KC8. The thermally very labile divalent [(Me3TACN)YbMe(μ‐Me)]2 is the first discrete donor adduct of a divalent dimethyl rare‐earth‐metal complex. [ABSTRACT FROM AUTHOR]

Using previously established salt‐metathesis procedures at low temperature, heterobimetallic ate complexes Li6EuII(n‐Bu)8(thf)6 and Li3YIII(i‐Bu)6(thf)4 could be synthesized and their solid‐state structures analyzed by X‐ray diffraction. Recently described complex Li3Y(n‐Bu)6(thf)4 was probed as a precursor in protonolyses with various amines, revealing distinct reaction pathways. Identified products comprise homoleptic amide Y[HNC6H3(mes)2‐2,6]3 (mes=C6H2Me3‐2,4,6), heteroleptic C−H‐bond activated Li3Y(n‐Bu)2[N(SiMe2CH2)(C6H3‐Me2‐3,5)]2(thf)5, and mixed amido/imido complex [LiY2(HNSiPh3)4(NSiPh3)2][Li(thf)2(OEt2)2]. [ABSTRACT FROM AUTHOR]

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Commercially available stock solutions of organolithium reagents are well‐implemented tools in organic and organometallic chemistry. However, such solutions are inherently contaminated with lithium halide salts, which can complicate certain synthesis protocols and purification processes. Here, we report the isolation of chloride‐free methyllithium employing K[N(SiMe3)2] as a halide‐trapping reagent. The influence of distinct LiCl contaminations on the 7Li‐NMR chemical shift is examined and their quantification demonstrated. The structural parameters of new chloride‐free monomeric methyllithium complex [(Me3TACN)LiCH3], ligated by an azacrown ether, are assessed by comparison with a halide‐contaminated variant and monomeric lithium chloride [(Me3TACN)LiCl], further emphasizing the effect of halide impurities. [ABSTRACT FROM AUTHOR]