Yttrium Anilido Hydride: Synthesis, Structure, and Reactivity

The synthesis, structure, and reactivity of the yttrium anilido hydride [LY(NH(DIPP))(μ-H)]₂ (<b>3</b>; L = [MeC(N(DIPP))CHC(Me)(NCH₂CH₂NMe₂)]⁻, DIPP = 2,6-^<i>i</i>Pr₂C₆H₃)) are reported. The protonolysis reaction of the yttrium dialkyl [LY(CH₂SiMe₃)₂] (<b>1</b>) with 1 equiv of 2,6-diisopropylaniline gave the yttrium anilido alkyl [LY(NH(DIPP))(CH₂SiMe₃)] (<b>2</b>), and a subsequent σ-bond metathesis reaction of <b>2</b> with 1 equiv of PhSiH₃ offered the yttrium anilido hydride <b>3</b>. The structure of <b>3</b> was characterized by X-ray crystallography, which showed that the complex is a μ-H dimer. <b>3</b> shows high reactivity toward a variety of unsaturated substrates, including imine, azobenzene, carbodiimide, isocyanide, ketone, and Mo(CO)₆, giving some structurally intriguing products

Tris(boratabenzene) Lanthanum Complexes: Synthesis, Structure, and Reactivity

A series of tris­(boratabenzene) lanthanum complexes were synthesized and structurally characterized. Salt elimination of anhydrous LaCl₃ with Li­[C₅H₅BR] (R = H, NEt₂) provided tris­(boratabenzene) lanthanum complexes [C₅H₅BH]₃­LaLiCl (<b>1</b>) and [C₅H₅BNEt₂]₃­LaLiCl­(THF) (<b>2</b>) in high yields. Hydroboration of 1-hexene or 3-hexyne with <b>1</b> gave the alkyl- or alkenyl-functionalized boratabenzene lanthanum complexes, [C₅H₅B­(CH₂)₅CH₃]₃­LaLiCl­(THF) (<b>3</b>) and [C₅H₅BC­(C₂H₅)CH­(C₂H₅)]₃­LaLiCl­(THF) (<b>4</b>), in good yields. Hydroboration of <i>N</i>,<i>N</i>′-diisopropylcarbodiimide with <b>1</b> gave the monohydroboration product [C₅H₅BN­(^<i>i</i>Pr)­CHN­(^<i>i</i>Pr)]­[C₅H₅BH]₂La (<b>5</b>) due to the steric bulk of the [C₅H₅BN­(^<i>i</i>Pr)­CHN­(^<i>i</i>Pr)]⁻ ligand. Complex <b>5</b> can undergo further hydroboration with 3-hexyne or dehydrogenative coupling with phenyl acetylene to afford [C₅H₅BN­(^<i>i</i>Pr)­CHN­(^<i>i</i>Pr)]­[C₅H₅BC­(C₂H₅)CH­(C₂H₅)]₂La (<b>6</b>) or [C₅H₅BN­(^<i>i</i>Pr)­CHN­(^<i>i</i>Pr)]­[C₅H₅BCCPh)]₂La (<b>7</b>)

1‑Methyl Boratabenzene Yttrium Alkyl: A Highly Active Catalyst for Dehydrocoupling of Me₂NH·BH₃

Catalytic activity of rare-earth metal complexes for dehydrocoupling of Me₂NH·BH₃ is deeply ligand- and metal ion-dependent, and 1-methyl boratabenzene yttrium alkyl shows very high activity for the reaction (TOF > 1000 h^–1). The transformation of Me₂NH·BH₃ into [Me₂N–BH₂]₂ proceeds through an intermediate Me₂NH–BH₂–NMe₂–BH₃

Synthesis and Structure of Silicon-Bridged Boratabenzene Fluorenyl Rare-Earth Metal Complexes

A silicon-bridged boratabenzene fluorenyl ligand [Me₂Si­(C₁₃H₈)­(C₅H₄BNEt₂)]^2– (<b>L</b>^2–) was designed and synthesized. By employment of this ligand, two divalent rare-earth metal complexes [Me₂Si­(C₁₃H₈)­(C₅H₄BNEt₂)]­Ln­(THF)₂ (Ln = Sm (<b>1</b>), Yb (<b>2</b>)) were obtained from salt metathesis of K₂[Me₂Si­(C₁₃H₈)­(C₅H₄BNEt₂)] (<b>K</b>_<b>2</b><b>L</b>) with LnI₂­(THF)₂ in THF. Complex <b>2</b> undergoes redox reaction with cyclooctatetraene to give a trivalent Yb complex [(C₈H₈)­Yb]₂­[μ-{Me₂Si­(C₁₃H₈)­(C₅H₄BNEt₂)}₂] (<b>3</b>), accompanied with oxidative coupling of two fluorenyl groups. A series of chloro-bridged trimeric trivalent rare-earth metal complexes [Li­(THF)₄]₂­[{[Me₂Si­(C₁₃H₈)­(C₅H₄BNEt₂)]­Ln­(μ-Cl)­Li­(THF)₃}₃­(μ-Cl)₃­(μ₃-Cl)₂] (Ln = Nd (<b>4</b>), Sm (<b>5</b>), and Gd (<b>6</b>)) were synthesized by reactions of Li₂[Me₂Si­(C₁₃H₈)­(C₅H₄BNEt₂)] (<b>Li</b>_<b>2</b><b>L</b>) with LnCl₃ in THF. Treatment of K₂[Me₂Si­(C₁₃H₈)­(C₅H₄BNEt₂)] (<b>K</b>_<b>2</b><b>L</b>) with LnI₃(THF)_<i>n</i> gave the monomeric complexes [Me₂Si­(C₁₃H₈)­(C₅H₄BNEt₂)]­LnI­(THF) (Ln = La (<b>7</b>), Nd (<b>8</b>), Sm (<b>9</b>), and Gd (<b>10</b>)). These iodides were subsequently reacted with K­[CH₂C₆H₄-<i>o</i>-NMe₂] to afford THF coordinated benzyl complexes [Me₂Si­(C₁₃H₈)­(C₅H₄BNEt₂)]­Ln­(CH₂C₆H₄-<i>o</i>-NMe₂)­(THF) (Ln = La (<b>11</b>), Nd (<b>12</b>), and Gd (<b>13a</b>)) and non-THF coordinated complex [Me₂Si­(C₁₃H₈)­(C₅H₄BNEt₂)]­Gd­(CH₂C₆H₄-<i>o</i>-NMe₂) (<b>13b</b>)

C–P or C–H Bond Cleavage of Phosphine Oxides Mediated by an Yttrium Hydride

Reactions of the yttrium anilido hydride [LY­(NH­(DIPP))­(μ-H)]₂ (<b>1</b>; L = [MeC­(N­(DIPP))­CHC­(Me)­(NCH₂CH₂NMe₂)]⁻, DIPP = 2,6-ⁱPr₂C₆H₃)) with three phosphine oxides and two phosphine sulfides are reported. The reaction of <b>1</b> with Ph₃PO gives C–P bond cleavage and an yttrium anilido phosphinoyl complex, while those with R₂MePO (R = Me, Ph) result in C–H bond cleavage and two yttrium anilido alkyl complexes. <b>1</b> also reacted with R₃PS (R = Me, Ph), which demonstrated P–S bond cleavage via hydride-based reduction and gave an yttrium anilido sulfide

Synthesis and Structure of Silicon-Bridged Boratabenzene Fluorenyl Rare-Earth Metal Complexes

A silicon-bridged boratabenzene fluorenyl ligand [Me₂Si­(C₁₃H₈)­(C₅H₄BNEt₂)]^2– (<b>L</b>^2–) was designed and synthesized. By employment of this ligand, two divalent rare-earth metal complexes [Me₂Si­(C₁₃H₈)­(C₅H₄BNEt₂)]­Ln­(THF)₂ (Ln = Sm (<b>1</b>), Yb (<b>2</b>)) were obtained from salt metathesis of K₂[Me₂Si­(C₁₃H₈)­(C₅H₄BNEt₂)] (<b>K</b>_<b>2</b><b>L</b>) with LnI₂­(THF)₂ in THF. Complex <b>2</b> undergoes redox reaction with cyclooctatetraene to give a trivalent Yb complex [(C₈H₈)­Yb]₂­[μ-{Me₂Si­(C₁₃H₈)­(C₅H₄BNEt₂)}₂] (<b>3</b>), accompanied with oxidative coupling of two fluorenyl groups. A series of chloro-bridged trimeric trivalent rare-earth metal complexes [Li­(THF)₄]₂­[{[Me₂Si­(C₁₃H₈)­(C₅H₄BNEt₂)]­Ln­(μ-Cl)­Li­(THF)₃}₃­(μ-Cl)₃­(μ₃-Cl)₂] (Ln = Nd (<b>4</b>), Sm (<b>5</b>), and Gd (<b>6</b>)) were synthesized by reactions of Li₂[Me₂Si­(C₁₃H₈)­(C₅H₄BNEt₂)] (<b>Li</b>_<b>2</b><b>L</b>) with LnCl₃ in THF. Treatment of K₂[Me₂Si­(C₁₃H₈)­(C₅H₄BNEt₂)] (<b>K</b>_<b>2</b><b>L</b>) with LnI₃(THF)_<i>n</i> gave the monomeric complexes [Me₂Si­(C₁₃H₈)­(C₅H₄BNEt₂)]­LnI­(THF) (Ln = La (<b>7</b>), Nd (<b>8</b>), Sm (<b>9</b>), and Gd (<b>10</b>)). These iodides were subsequently reacted with K­[CH₂C₆H₄-<i>o</i>-NMe₂] to afford THF coordinated benzyl complexes [Me₂Si­(C₁₃H₈)­(C₅H₄BNEt₂)]­Ln­(CH₂C₆H₄-<i>o</i>-NMe₂)­(THF) (Ln = La (<b>11</b>), Nd (<b>12</b>), and Gd (<b>13a</b>)) and non-THF coordinated complex [Me₂Si­(C₁₃H₈)­(C₅H₄BNEt₂)]­Gd­(CH₂C₆H₄-<i>o</i>-NMe₂) (<b>13b</b>)

Reversible Addition of the Si–H Bond of Phenylsilane to the ScN Bond of a Scandium Terminal Imido Complex

The facile and reversible addition of the Si–H bond of phenylsilane to the ScN bond of the scandium terminal imido complex [LScNDIPP­(DMAP)] (<b>1</b>; L  [MeC­(N­(DIPP))­CHC­(Me)­(NCH₂CH₂NMe)]⁻, DIPP = 2,6-^<i>i</i>Pr₂C₆H₃) is reported. The reaction gives the scandium anilido hydride [LSc­(H)­(N­(DIPP)­(SiH₂Ph))] (<b>2</b>), and a labeling experiment shows a rapid σ-bond metathesis between Sc–H of the formed scandium anilido hydride and Si–H of phenylsilane during the reaction. <b>2</b> was trapped by an insertion reaction with diphenylcarbodiimide, giving the stable scandium anilido amidinate [LSc­(N­(DIPP)­(SiH₂Ph))­(κ²(<i>N</i>,<i>N</i>′)-PhNCHNPh)] (<b>3</b>). Furthermore, the scandium terminal imido complex can efficiently catalyze the hydrosilylation of <i>N</i>-benzylidenepropan-1-amine. The reaction was completed within 2 h at 50 °C with 5 mol % of catalyst loading and highly selectively produced the monoaminosilane

Reactivity of Scandium Terminal Imido Complex toward Boranes: C(sp³)–H Bond Borylation and B–O Bond Cleavage

Scandium terminal imido complex [(NNNN)­ScNDIPP] (<b>2</b>; NNNN = [MeC­(N­(DIPP))­CHC­(Me)­(NCH₂CH₂NMeCH₂CH₂NMe₂)]⁻, DIPP = 2,6-^<i>i</i>Pr₂C₆H₃) reacts with 9-borabicyclononane (9-BBN) to give scandium borohydride [(NNNN­(B)­H)­Sc­(N­(H)­DIPP)] (<b>3</b>; NNNN­(B)H = [MeC­(N­(DIPP))­CHC­(Me)­(NCH₂CH₂NMeCH₂CH₂N­(Me)­CH₂(BBN)]^2–), and C­(sp³)–H bond borylation of the NNNN ligand occurs during this reaction. In contrast, the reaction between complex <b>2</b> and catecholborane (CatBH) gives scandium catecholate [(NNNN)­Sc­(Cat)] (<b>4</b>), and B–O bond cleavage happens during this reaction. Both <b>3</b> and <b>4</b> have been well-characterized including the single-crystal X-ray diffraction analysis. Reaction of <b>2</b> with bis­(catecholato)­diboron (CatB–BCat) also gives a B–O bond cleavage product

A Scandium Complex Bearing Both Methylidene and Phosphinidene Ligands: Synthesis, Structure, and Reactivity

The scandium complex bearing both methylidene and phosphinidene ligands, [(LSc)₂­(μ₂-CH₂)­(μ₂-PDIPP)] (L = [MeC­(NDIPP)­CHC­(NDIPP)­Me]⁻, DIPP = 2,6-(^<i>i</i>Pr)₂C₆H₃) (<b>2</b>), has been synthesized, and its reactivity has been investigated. Reaction of scandium methyl phosphide [LSc­(Me)­{P­(H)­DIPP}] with 1 equiv of scandium dimethyl complex [LScMe₂] in toluene at 60 °C provided complex <b>2</b> in good yield, and the structure of complex <b>2</b> was determined by single-crystal X-ray diffraction. Complex <b>2</b> easily undergoes nucleophilic addition reactions with CO₂, CS₂, benzonitrile, and <i>tert</i>-butyl isocyanide. In the above reactions, the unsaturated substrates insert into the Sc–C­(methylidene) bond to give some interesting dianionic ligands while the Sc–P­(phosphinidene) bond remains untouched. The bonding situation of complex <b>2</b> was analyzed using DFT methods, indicating a more covalent bond between the scandium ion and the phosphinidene ligand than between the scandium ion and the methyl­idene ligand

Nonchelated Phosphoniomethylidene Complexes of Scandium and Lutetium

The first phosphoniomethylidene complexes of scandium and lutetium, [<b>L</b>Ln­(CHPPh₃)­X] (<b>L</b> = [MeC­(NDIPP)­CHC­(NDIPP)­Me]⁻; Ln = Sc, X = Me, I, TfO; Ln = Lu, X = CH₂SiMe₃), have been synthesized and fully characterized. DFT calculations clearly demonstrate the presence of an allylic Ln, C, P π-type interaction in these complexes. X-ray diffraction indicates that the scandium iodide complex has the shortest Sc–C bond length to date (2.044(5) Å). These phosphoniomethylidene complexes readily convert into the ylide complexes, and the reactivity is affected by both X^– anion and Ln³⁺ ion. The reaction of lutetium complex with imine shows a rapid insertion of imine into the Lu–C­(alkylidene) bond. DFT calculations indicate that, although the bonding situation seems similar to that of the scandium analog, the strong negative charge at the alkylidene carbon is not sufficiently screened by one hydrogen in the lutetium complex because of a more ionic bonding, and therefore, the reactivity of the lutetium complex is much higher