Reactions of Cp₃Y with Benzophenone: A Simple and Efficient Method for Transformation of Unsubstituted Cyclopentadienyl to Bridged <i>ansa</i>-Cyclopentadienyl/Alkoxyl Ligand

Insertion of benzophenone into the Y−Cp (Cp = C5H5) bond and two new reactivity patterns of the Cp-substituted alkoxide complexes have been established, by which an efficient and convenient method for conversion of the unsubstituted cyclopentadienyl group to the single-carbon-bridged ansa-cyclopentadienyl/alkoxyl ligand by using a simple ketone as the functionalizing reagent is developed. All products including the four-center interaction precursor of the insertion have been characterized by X-ray structural analyses

Rare-Earth-Metal-Catalyzed Addition of Terminal Monoalkynes and Dialkynes with Aryl-Substituted Symmetrical or Unsymmetrical Carbodiimides

A high-efficiency and atom-economic route for the synthesis of N-aryl-substituted propiolamidines was established through the addition of terminal alkynes with aryl-substituted symmetrical or unsymmetrical carbodiimides catalyzed by mixed TpMe2/Cp rare-earth-metal alkyl complexes (TpMe2)­CpLnCH2Ph­(THF) (1Ln). Moreover, the gadolinium alkyl complex 1Gd can also serve as a catalyst for the double addition of dialkynes with carbodiimides. Mechanism studies indicated that the variable coordination modes (κ3 or κ2) of the TpMe2 ligand on the rare-earth-metal species may play an important role in the catalytic cycles

Rare-Earth-Metal-Catalyzed Addition of Terminal Monoalkynes and Dialkynes with Aryl-Substituted Symmetrical or Unsymmetrical Carbodiimides

A high-efficiency and atom-economic route for the synthesis of N-aryl-substituted propiolamidines was established through the addition of terminal alkynes with aryl-substituted symmetrical or unsymmetrical carbodiimides catalyzed by mixed Tp^Me2/Cp rare-earth-metal alkyl complexes (Tp^Me2)­CpLnCH₂Ph­(THF) (<b>1</b>^<b>Ln</b>). Moreover, the gadolinium alkyl complex <b>1</b>^<b>Gd</b> can also serve as a catalyst for the double addition of dialkynes with carbodiimides. Mechanism studies indicated that the variable coordination modes (κ³ or κ²) of the Tp^Me2 ligand on the rare-earth-metal species may play an important role in the catalytic cycles

Versatile Reactivity of β‑Diketiminato-Supported Yttrium Dialkyl Complex toward Aromatic N‑Heterocycles

The reactions of β-diketiminatoyttrium dialkyl complex LY­(CH2Ph)2(THF) (1, L = [{N­(2,6-iPr2C6H3)­C­(Me)}2CH]−) with a series of aromatic N-heterocycles such as 2-phenylpyridine, benzothiazole, and benzoxazole were studied and displayed discrete reactivity including C–H activation, C–C coupling, ring-opening/insertion, and dearomatization. The reaction of 1 with 2-phenylpyridine in 1:2 molar ratio in THF at 30 °C for 14 days afforded a structurally characterized metal complex, LY­(η2-N,C-C5H4NC6H4-2)­[C5H4N­(CH2Ph-4)­Ph] (2), in 73% isolated yield, indicating the occurrence of phenyl ring C­(sp2)–H activation and pyridine ring 1,4-addition/dearomatization. However, when this reaction was done at 5 °C for 7 days, it gave the pyridine ring 1,2-addition product LY­(η2-N,C-C5H4NC6H4-2)­[C5H4N­(CH2Ph-2)­Ph] (3) in 54% isolated yield. Further investigations revealed that complex 2 is the thermodynamic controlled product and complex 3 is the kinetically controlled product; 3 converted slowly into 2, as confirmed by 1H NMR spectroscopy. The equimolar reaction of 1 with benzothiazole or benzoxazole produced two C–C coupling/ring-opening/insertion products, LY­[η2-S,N-SC6H4NCH­(CH2Ph)2]­(THF) (4) and {LY­[μ-η2:η1-O,N-OC6H4NCH­(CH2Ph)2]}2 (5), in 84% and 78% isolated yields, respectively

Synthesis, Structural Characterization, and Reactivity of Mono(amidinate) Rare-Earth-Metal Bis(aminobenzyl) Complexes

Three kinds of solvated lithium amidinates with different coordination models were obtained via recrystallization of [PhC­(NC₆H₄^<i>i</i>Pr₂-2,6)₂]­Li­(THF) (<b>1a</b>) in different solvents. Treatment of <i>o</i>-Me₂NC₆H₄CH₂Li with LLnCl₂(THF)_<i>n</i> (<b>2</b>; L = [PhC­(NC₆H₄^<i>i</i>Pr₂-2,6)₂]⁻ (NCN^dipp), [<i>o</i>-Me₂NC₆H₄CH₂C­(NC₆H₄^<i>i</i>Pr₂-2,6)₂]⁻ (NCN^dipp′)) formed in situ from reaction of LnCl₃(THF)_<i>x</i> with LLi­(THF) gave the rare-earth-metal bis­(aminobenzyl) complexes LLn­(CH₂C₆H₄NMe₂-<i>o</i>)₂ (L = NCN^dipp, Ln = Sc (<b>3a</b>), Y (<b>3b</b>), Lu (<b>3c</b>); L = NCN^dipp′, Ln = Sc (<b>3d</b>), Lu (<b>3e</b>)) in high yields. Reactions of complexes <b>3</b> with CO₂, PhNCO, 2,6-diisopropylaniline, and S have been explored. CO₂ inserted into each Ln–C bond of complexes <b>3a</b>–<b>c</b> to form the dual-core complexes [(NCN^dipp)­Sc­(μ-η¹:η¹-O₂CCH₂C₆H₄NMe₂-<i>o</i>)₂]₂ (<b>4a</b>) and [(NCN^dipp)­Ln­(μ-η¹:η²-O₂CCH₂C₆H₄NMe₂-<i>o</i>)­(μ-η¹:η¹-O₂CCH₂C₆H₄NMe₂-<i>o</i>)]₂ (Ln = Y (<b>4b</b>), Lu (<b>4c</b>)). The reaction of <b>3b</b>,<b>c</b>,<b>e</b> with PhNCO produced LLu­[OC­(CH₂C₆H₄NMe₂-<i>o</i>)­NPh]₂(thf) (L = NCN^dipp, Ln = Y (<b>5b</b>), Lu (<b>5c</b>); L = NCN^dipp′, Ln = Lu (<b>5e</b>)). Protonolysis of <b>3a</b>,<b>b</b> by 2,6-diisopropylaniline formed straightforwardly the μ₂-imido complexes [(NCN^dipp)­Ln­(μ-NC₆H₄^<i>i</i>Pr₂-2,6)]₂ (Ln = Sc (<b>6a</b>), Lu (<b>6c</b>)). Reaction of <b>3e</b> with S₈ afforded the sulfur insertion products (NCN^dipp′)­Lu­(CH₂C₆H₄NMe₂-<i>o</i>)­(SCH₂C₆H₄NMe₂-<i>o</i>)­(thf) (<b>7e</b>) and (NCN^dipp′)­Lu­(SCH₂C₆H₄NMe₂-<i>o</i>)₂(thf)₂ (<b>7f</b>) in high yields, respectively, depending on the stoichiometric ratio. All of these complexes were fully characterized by elemental analysis, NMR spectroscopy, and X-ray structural determinations

Synthesis, Structural Characterization, and Reactivity of Mono(amidinate) Rare-Earth-Metal Bis(aminobenzyl) Complexes

Three kinds of solvated lithium amidinates with different coordination models were obtained via recrystallization of [PhC­(NC₆H₄^<i>i</i>Pr₂-2,6)₂]­Li­(THF) (<b>1a</b>) in different solvents. Treatment of <i>o</i>-Me₂NC₆H₄CH₂Li with LLnCl₂(THF)_<i>n</i> (<b>2</b>; L = [PhC­(NC₆H₄^<i>i</i>Pr₂-2,6)₂]⁻ (NCN^dipp), [<i>o</i>-Me₂NC₆H₄CH₂C­(NC₆H₄^<i>i</i>Pr₂-2,6)₂]⁻ (NCN^dipp′)) formed in situ from reaction of LnCl₃(THF)_<i>x</i> with LLi­(THF) gave the rare-earth-metal bis­(aminobenzyl) complexes LLn­(CH₂C₆H₄NMe₂-<i>o</i>)₂ (L = NCN^dipp, Ln = Sc (<b>3a</b>), Y (<b>3b</b>), Lu (<b>3c</b>); L = NCN^dipp′, Ln = Sc (<b>3d</b>), Lu (<b>3e</b>)) in high yields. Reactions of complexes <b>3</b> with CO₂, PhNCO, 2,6-diisopropylaniline, and S have been explored. CO₂ inserted into each Ln–C bond of complexes <b>3a</b>–<b>c</b> to form the dual-core complexes [(NCN^dipp)­Sc­(μ-η¹:η¹-O₂CCH₂C₆H₄NMe₂-<i>o</i>)₂]₂ (<b>4a</b>) and [(NCN^dipp)­Ln­(μ-η¹:η²-O₂CCH₂C₆H₄NMe₂-<i>o</i>)­(μ-η¹:η¹-O₂CCH₂C₆H₄NMe₂-<i>o</i>)]₂ (Ln = Y (<b>4b</b>), Lu (<b>4c</b>)). The reaction of <b>3b</b>,<b>c</b>,<b>e</b> with PhNCO produced LLu­[OC­(CH₂C₆H₄NMe₂-<i>o</i>)­NPh]₂(thf) (L = NCN^dipp, Ln = Y (<b>5b</b>), Lu (<b>5c</b>); L = NCN^dipp′, Ln = Lu (<b>5e</b>)). Protonolysis of <b>3a</b>,<b>b</b> by 2,6-diisopropylaniline formed straightforwardly the μ₂-imido complexes [(NCN^dipp)­Ln­(μ-NC₆H₄^<i>i</i>Pr₂-2,6)]₂ (Ln = Sc (<b>6a</b>), Lu (<b>6c</b>)). Reaction of <b>3e</b> with S₈ afforded the sulfur insertion products (NCN^dipp′)­Lu­(CH₂C₆H₄NMe₂-<i>o</i>)­(SCH₂C₆H₄NMe₂-<i>o</i>)­(thf) (<b>7e</b>) and (NCN^dipp′)­Lu­(SCH₂C₆H₄NMe₂-<i>o</i>)₂(thf)₂ (<b>7f</b>) in high yields, respectively, depending on the stoichiometric ratio. All of these complexes were fully characterized by elemental analysis, NMR spectroscopy, and X-ray structural determinations

Versatile Reactivity of β‑Diketiminato-Supported Yttrium Dialkyl Complex toward Aromatic N‑Heterocycles

The reactions of β-diketiminatoyttrium dialkyl complex LY­(CH₂Ph)₂(THF) (<b>1</b>, L = [{N­(2,6-^<i>i</i>Pr₂C₆H₃)­C­(Me)}₂CH]⁻) with a series of aromatic N-heterocycles such as 2-phenylpyridine, benzothiazole, and benzoxazole were studied and displayed discrete reactivity including C–H activation, C–C coupling, ring-opening/insertion, and dearomatization. The reaction of <b>1</b> with 2-phenylpyridine in 1:2 molar ratio in THF at 30 °C for 14 days afforded a structurally characterized metal complex, LY­(η²-<i>N,C</i>-C₅H₄NC₆H₄-2)­[C₅H₄N­(CH₂Ph-4)­Ph] (<b>2</b>), in 73% isolated yield, indicating the occurrence of phenyl ring C­(sp²)–H activation and pyridine ring 1,4-addition/dearomatization. However, when this reaction was done at 5 °C for 7 days, it gave the pyridine ring 1,2-addition product LY­(η²-<i>N,C</i>-C₅H₄NC₆H₄-2)­[C₅H₄N­(CH₂Ph-2)­Ph] (<b>3</b>) in 54% isolated yield. Further investigations revealed that complex <b>2</b> is the thermodynamic controlled product and complex <b>3</b> is the kinetically controlled product; <b>3</b> converted slowly into <b>2</b>, as confirmed by ¹H NMR spectroscopy. The equimolar reaction of <b>1</b> with benzothiazole or benzoxazole produced two C–C coupling/ring-opening/insertion products, LY­[η²-<i>S,N</i>-SC₆H₄NCH­(CH₂Ph)₂]­(THF) (<b>4</b>) and {LY­[μ-η²:η¹-<i>O,N</i>-OC₆H₄NCH­(CH₂Ph)₂]}₂ (<b>5</b>), in 84% and 78% isolated yields, respectively

Transition-Metal-Free Synthesis of Aryl Trifluoromethyl Thioethers through Indirect Trifluoromethylthiolation of Sodium Arylsulfinate with TMSCF₃

Herein, we report an indirect trifluoromethylthiolation of sodium arylsulfinates. This transition-metal-free reaction significantly provides an environmentally friendly and practical synthetic method for aryl trifluoromethyl thioethers using commercial Ruppert–Prakash reagent TMSCF3. This approach is also a potential alternative to the current industrial production method owing to facile substrates, excellent functional group compatibility, and operational simplicity

Synthesis and Reactivities of Guanidinate Dianion Complexes of Heterobimetallic Lanthanide−Lithium Cp₂Ln[(CyN)₂CNPh]Li(THF)₃

The treatment of Cp3Ln with 1 equiv of N,N′-dicyclohexyl-N′′-phenylguanidine followed by reacting with butyllithium yields a series of novel guanidinate dianion complexes of heterobimetallic lanthanide−lithium with formula Cp2Ln[(CyN)2CNPh]Li(THF)3 (Ln = Yb (1a), Er (1b), Y (1c), Dy (1d)). Reactivities of these dianionic guanidinate complexes toward various electrophiles have been investigated. Reaction of 1 with Me2RSiCl produced tetrasubstituted guanidinate monoanion complexes Cp2Ln[(CyN)2CN(Ph)SiRMe2] ((R = Me, Ln = Yb (2a), Er (2b), Y (2c); R = tBu, Ln = Yb (3a), Er (3b)), indicating that the Li−N bond is preferred to couple with chlorosilanes. In contrast, the regioselective functionalization of the NCy group bonded to the lanthanide ion was achieved by reaction of 1a with Me2SiCl2 to produce Me2Si(CyN)2CNPh (4) and Cp2YbCl(THF) (5). Significantly, treatment of 1d with PhCOCl leads to the cleavage of one C−N bond of the dianionic guanidinate, giving the acylamino complex [Cp2Dy(OC(Ph)NCy)]2 (6). These results have shown that the active site of the dianionic guanidinate ligand is tunable due to the delocalization of the two negative charges on the three N atoms. All the compounds were characterized by elemental analysis and spectroscopic methods. The structures of compounds 1−6 are also determined through X-ray single-crystal diffraction analysis

Synthesis and Reactivities of Guanidinate Dianion Complexes of Heterobimetallic Lanthanide−Lithium Cp₂Ln[(CyN)₂CNPh]Li(THF)₃

The treatment of Cp3Ln with 1 equiv of N,N′-dicyclohexyl-N′′-phenylguanidine followed by reacting with butyllithium yields a series of novel guanidinate dianion complexes of heterobimetallic lanthanide−lithium with formula Cp2Ln[(CyN)2CNPh]Li(THF)3 (Ln = Yb (1a), Er (1b), Y (1c), Dy (1d)). Reactivities of these dianionic guanidinate complexes toward various electrophiles have been investigated. Reaction of 1 with Me2RSiCl produced tetrasubstituted guanidinate monoanion complexes Cp2Ln[(CyN)2CN(Ph)SiRMe2] ((R = Me, Ln = Yb (2a), Er (2b), Y (2c); R = tBu, Ln = Yb (3a), Er (3b)), indicating that the Li−N bond is preferred to couple with chlorosilanes. In contrast, the regioselective functionalization of the NCy group bonded to the lanthanide ion was achieved by reaction of 1a with Me2SiCl2 to produce Me2Si(CyN)2CNPh (4) and Cp2YbCl(THF) (5). Significantly, treatment of 1d with PhCOCl leads to the cleavage of one C−N bond of the dianionic guanidinate, giving the acylamino complex [Cp2Dy(OC(Ph)NCy)]2 (6). These results have shown that the active site of the dianionic guanidinate ligand is tunable due to the delocalization of the two negative charges on the three N atoms. All the compounds were characterized by elemental analysis and spectroscopic methods. The structures of compounds 1−6 are also determined through X-ray single-crystal diffraction analysis