Imide complexes [(TptBu,Me)Y(=NC6H3Me2‐2,6)(DMAP)] and [(TptBu,Me)Lu{=NC6H3(CF3)2‐3,5}(DMAP)] were obtained by Lewis base induced methane elimination of the corresponding methyl/anilide complexes, which were synthesized from [(TptBu,Me)LuMe2] and [(TptBu,Me)YMe(GaMe4)], respectively. Terminal Ln=N bonding is evidenced by very short Ln–N distances [min. 1.993(5) Å] and almost linear Ln–N–C(aryl) bond angles.
The reaction of monomeric [(Tp(tBu,Me) )LuMe2 ] (Tp(tBu,Me) =tris(3-Me-5-tBu-pyrazolyl)borate) with primary aliphatic amines H2 NR (R=tBu, Ad=adamantyl) led to lutetium methyl primary amide complexes [(Tp(tBu,Me) )LuMe(NHR)], the solid-state structures of which were determined by XRD analyses. The mixed methyl/tetramethylaluminate compounds [(Tp(tBu,Me) )LnMe({μ2 -Me}AlMe3 )] (Ln=Y, Ho) reacted selectively and in high yield with H2 NR, according to methane elimination, to afford heterobimetallic complexes: [(Tp(tBu,Me) )Ln({μ2 -Me}AlMe2 )(μ2 -NR)] (Ln=Y, Ho). X-ray structure analyses revealed that the monomeric alkylaluminum-supported imide complexes were isostructural, featuring bridging methyl and imido ligands. Deeper insight into the fluxional behavior in solution was gained by (1) H and (13) C NMR spectroscopic studies at variable temperatures and (1) H-(89) Y HSQC NMR spectroscopy. Treatment of [(Tp(tBu,Me) )LnMe(AlMe4 )] with H2 NtBu gave dimethyl compounds [(Tp(tBu,Me) )LnMe2 ] as minor side products for the mid-sized metals yttrium and holmium and in high yield for the smaller lutetium. Preparative-scale amounts of complexes [(Tp(tBu,Me) )LnMe2 ] (Ln=Y, Ho, Lu) were made accessible through aluminate cleavage of [(Tp(tBu,Me) )LnMe(AlMe4 )] with N,N,N',N'-tetramethylethylenediamine (tmeda). The solid-state structures of [(Tp(tBu,Me) )HoMe(AlMe4 )] and [(Tp(tBu,Me) )HoMe2 ] were analyzed by XRD.
Readily accessible and easy-to-use phenyliodine(III) dichloride, PhICl(2), has been established as an innovative and superior reagent for the one-electron oxidation of cerium(III) complexes, comprising amide, amidinate, and cyclopentadienyl derivatives. Its use allowed the successful synthesis and structural characterization of the first members of three new classes of chloro-functionalized (organo)cerium(IV) compounds, including the long sought-after Cp(3)CeCl.
Bis(dimethylsilyl)amide and bis(dimethylphenylsilyl)amide complexes of the divalent transition metals chromium, manganese, and cobalt were synthesized. Dimeric, donor-free {Mn[N(SiHMe2)2]2}2 could be obtained via two different pathways, a salt metathesis route (utilizing MnCl2(thf)1.5 and LiN(SiHMe2)2) and a transsilylamination protocol (utilizing Mn[N(SiMe3)2]2(thf) and HN(SiHMe2)2). Addition of 1,1,3,3-tetramethylethylendiamine (tmeda) to {Mn[N(SiHMe2)2]2}2 yielded the monomeric adduct Mn[N(SiHMe2)2]2(tmeda). The syntheses of Cr[N(SiHMe2)2]2(tmeda), Co[N(SiMe3)2][N(SiHMe2)2](tmeda), and Co[N(SiHMe2)2]2(tmeda) were achieved by transsilylamination from Cr[N(SiMe3)2]2(tmeda) and {Co[N(SiMe3)2]2}2(μ-tmeda), respectively. Bis(dimethylphenylsilyl)amide complexes Mn[N(SiMe2Ph)2]2, Cr[N(SiMe2Ph)2]2, and Co[N(SiMe2Ph)2]2(thf) were obtained via salt metathesis employing MCl2(thf)x (M = Cr, Mn, Co) with equimolar amounts of LiN(SiMe2Ph)2 in n-hexane. Treatment of CrCl2 with LiN(SiMe2Ph)2 in thf gave Cr[N(SiMe2Ph)2]2(thf)2, featuring an almost square planar trans-coordination. All complexes were examined by elemental analyses, DRIFT and UV-vis spectroscopy, as well as X-ray structure analysis, paying particular attention to secondary M---SiH β-agostic and M---π(arene) interactions. Magnetic moments were determined by Evans' method.
Compounds combining the large rare-earth-metal (Ln) centers with the smallest anionic ligand, H À (hydrido), continue to pose challenging questions both in fundamental and applied chemistry. [1] The inherent bonding properties in solid-state binary LnH x phases (e.g., causing metallic behavior) as well as in ligand-supported molecular counterparts (revealing unique cluster chemistry, see Supporting Information) have been the focus of extensive research. Moreover, heterobimetallic solid-state materials, such as Ni 5 LaH x , feature approved rechargeable battery components or, such as LnAlH 6 (obtained from LnCl 3 and NaAlH 4 by the release of hydrogen), are discussed as intermediate-temperature hydrogen-storage materials. [2] On the other hand, the quest for soluble molecular hydrides has triggered immense research efforts. In the meantime, mono and dihydrido derivatives "L 2 LnH" and "LLnH 2 " (L = monoanionic ligand), respectively, are assigned a crucial role in a variety of stoichiometric and catalytic transformations, [3] whereas complexes of type [LnH 3 (Do) x ] (Do = neutral donor ligand) are still elusive. While mono hydride complexes can exist as monomers, e.g., [(C 5 H 2 tBu 3 ) 2 CeH], [4] dihydrido species "LLnH 2 ", carrying only one ancillary ligand per lanthanide center, tend to form polynuclear complexes (see Supporting Information) containing as few as two [5] and up to six lanthanide metal centers. [6] Several types of ancillary ligands have been employed in an effort to stabilize complexes of low nuclearity, including sterically demanding cyclopentadienyl derivatives such as C 5 Me 4 SiMe 3[6] tris(pyrazolyl)borato scorpionates, [7] tetraazacycloamido, [8] bis(phosphinophenyl)amido pincer, [5] and pyridylamido [9] ligands as well as chelating diamido ligands (see Supporting Information). [10] However, the synthesis of a monomeric rare-earth-metal dihydride was not successful to date.The group of Takats used the sterically demanding hydrotris(3-tert-butyl-5-methylpyrazolyl)borato ligand (Tp tBu,Me ) to stabilize Ln 2+ centers in species such as alkyls, [11] carbenes, [12] amides, [11b] halides, [11,13] or hydrides [14] and was also able to obtain lanthanide dihydride complexes using the less-bulky dimethyl, diisopropyl, or unsubstituted derivative of the Tp ligand, but reported the formation of a mixture of products for the more bulky Tp tBu,Me ligand
The μ2-imide complexes [Ln(AlMe4)(μ2-Nmes*)] x (mes* = C6H2 tBu3-2,4,6) (Ln = Y, La, Nd, Lu) are synthesized from homoleptic heterobimetallic complexes Ln(AlMe4)3 utilizing two distinct protocols: reaction with 2,4,6-tri-tert-butylaniline in hexane via methane elimination or with potassium (2,4,6-tri-tert-butylphenyl)amide in toluene according to a salt metathesis–protonolysis tandem reaction. Complexes [Ln(AlMe4)(μ2-Nmes*)]2 (Ln = Y, Nd, Lu) revealed isomorphous solid-state structures, featuring an asymmetrically bridged Ln2N2 core with very short Ln–N distances (2.071(1)–2.155(3) Å). In the solid-state structure of the lanthanum derivative similar dimeric subunits assemble as La4Al4 oligomers through μ2-η1:η2-bridging tetramethylaluminato moieties. [La(AlMe4)(μ2-Nmes*)]4 displays La---arene interactions (2.702(6) Å) that are considerably shorter than the La(μ-CH3)aluminato bond lengths.
The reactions of common rare-earth metal chloride, borohydride, and triflate precursors -LnCl 3 (thf) x , Ln(BH 4 ) 3 (thf) 3
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