Effects of Ionic Liquids on Piezoelectric Properties of Electrospun Poly(L‑lactic acid) Nanofiber Membranes

The development of environmentally friendly, degradable piezoelectric materials is of great significance for the environment. Poly(L-lactic acid) (PLLA) is a promising piezoelectric material as a degradable material. Here, we have introduced a series of ionic liquids (ILs) into PLLA spinning solution, and the PLLA/IL composite nanofiber membranes are prepared by electrospinning method. When the conductivity of the spinning solution is below 400 μS·cm–1, the addition of ILs, especially [EMIm][PF6], can significantly improve the morphology and piezoelectric properties of the PLLA/IL composite nanofiber membrane with the output voltage of 2.3 V under the pressure of 5 N, which is 4 times that of the PLLA nanofiber membrane. The improvement of the piezoelectric properties of PLLA/IL nanofiber membrane may be due to the high dipole moment generated by the CO dipole after the interaction between the O atom in CO on the PLLA molecular chain and the [EMIm]+ cation in the IL. This work has elucidated the effects of ILs on the properties of spinning solution and the piezoelectric properties of PLLA, which can provide a theoretical basis for the selection of the preparation system of piezoelectric polymer and inspire the development of environmentally friendly flexible piezoelectric materials

CNC-Pincer Rare-Earth Metal Amido Complexes with a Diarylamido Linked Biscarbene Ligand: Synthesis, Characterization, and Catalytic Activity

In preparation of CNC-pincer rare-earth metal amido complexes with a diarylamido linked biscarbene ligand, it is found that conditions have a key influence on final products. Reaction of a THF suspension of bis­[2-(3-benzyl­imidazolium)-4-methyl­phenyl]­amine dichlorides (H₃<b>L</b>Cl₂) with [(Me₃Si)₂­N]₃­RE­(μ-Cl)­Li­(THF)₃ (RE = Yb, Eu, Sm) in THF at room temperature afforded the only unexpected fused-heterocyclic compound 8,9-dibenzyl-3,14-dimethyl-8<i>a</i>,9-dihydro-8<i>H</i>-benzo­[4,5]­imidazo­[2′,1′:2,3]­imidazo­[1,2-<i>a</i>]­imidazo­[2,1-<i>c</i>]­quinoxaline (<b>1</b>) containing an imidazolyl ring and a piperidyl ring, which formed through carbene C–C and C–N coupling. However, the reaction of H₃<b>L</b>Cl₂ with [(Me₃Si)₂­N]₃­Er­(μ-Cl)­Li­(THF)₃ in toluene afforded the CNC-pincer erbium amido complex incorporating a diarylamido linked biscarbene ligand <b>L</b>Er­[N­(SiMe₃)₂]₂ (<b>2</b>) in low yield and the above fused-heterocyclic compound <b>1</b>. The stepwise reaction of H₃<b>L</b>Cl₂ with strong bases (<i>n</i>-BuLi or LiCH₂SiMe₃) in THF for 4 h, followed by treatment with [(Me₃Si)₂­N]₃­RE­(μ-Cl)­Li­(THF)₃, generated zwitterion complexes [<b>L</b>₂RE]­[RECl­{N­(SiMe₃)₂}₃] (<b>L</b> = [4-CH₃-2-{(C₆H₄CH₂-[N­(CH)₂­CN]}­C₆H₃]₂N; RE = Y (<b>3</b>), Er (<b>4</b>), Yb (<b>5</b>)) in less than 20% yields together with fused-heterocyclic compound <b>1</b>. Additionally, the reaction of H₃<b>L</b>Cl₂ with 6 equiv of NaN­(SiMe₃)₂ in THF for 4 h, followed by treatment with YbCl₃, generated a novel discrete complex [<b>L</b>₂Yb]­[{Na­(μ-N­(SiMe₃)₂)}₅­(μ₅-Cl)] (<b>6</b>). The one-pot reaction of H₃<b>L</b>Cl₂ with <i>n</i>-BuLi, followed by reaction with [(Me₃Si)₂­N]₃­RE­(μ-Cl)­Li­(THF)₃ in THF at −78 °C, generated the CNC-pincer lanthanide bisamido complexes <b>L</b>RE­[N­(SiMe₃)₂]₂ (RE = Er (<b>2</b>), Y (<b>7</b>), Sm (<b>8</b>), Eu (<b>9</b>)) in moderate yields. These kinds of biscarbene supported pincer bisamido complexes could also be prepared by a one-pot reaction of bis­(imidazolium) salt (H₃<b>L</b>Cl₂) with 5 equiv of NaN­(SiMe₃)₂, followed by treatment with RECl₃, in good yields at −78 °C. Investigation of the catalytic activity of complexes <b>2</b> and <b>7</b>–<b>9</b> indicated that all complexes showed a high activity toward the addition of terminal alkynes to carbodiimides producing propiolimidines, which represents the first example of rare-earth metal CNC-pincer-type catalysts applied for catalytic C–H bond addition of terminal alkynes to carbodiimides at room temperature

Novel Lanthanide Amides Incorporating Neutral Pyrrole Ligand in a Constrained Geometry Architecture: Synthesis, Characterization, Reaction, and Catalytic Activity

The first series of lanthanide amido complexes incorporating a neutral pyrrole ligand in a constrained geometry architecture were synthesized, and their bonding, reactions, and catalytic activities were studied. Treatment of [(Me₃Si)₂N]₃Ln­(μ-Cl)­Li­(THF)₃ with 1 equiv of (<i>N</i>-C₆H₅NHCH₂CH₂)­(2,5-Me₂C₄H₂N) (<b>1</b>) afforded the first example of bisamido lanthanide complexes having the neutral pyrrole η⁵-bonded to the metal formulated as [η⁵:η¹-(<i>N</i>-C₆H₅NCH₂CH₂)­(2,5-Me₂C₄H₂N)]­Ln­[N­(SiMe₃)₂]₂ (Ln = La (<b>2</b>) and Nd (<b>3</b>)). Reaction of [(Me₃Si)₂N]₃Sm­(μ-Cl)­Li­(THF)₃ with 2 equiv of <b>1</b> produced the complex [η⁵:η¹-(<i>N</i>-C₆H₅NCH₂CH₂)­(2,5-Me₂C₄H₂N)]­[η¹-(<i>N</i>-C₆H₅NCH₂CH₂)­(2,5-Me₂C₄H₂N)]]­SmN­(SiMe₃)₂ (<b>4</b>). Treatment of <b>3</b> with 2 equiv of <b>1</b> gave the sandwich neodymium complex [η⁵:η¹-(<i>N</i>-C₆H₅NCH₂CH₂)­(2,5-Me₂C₄H₂N)]₂Nd­[η¹-(<i>N</i>-C₆H₅NCH₂CH₂)­(2,5-Me₂C₄H₂N)] (<b>5</b>), in which two neutral pyrroles bonded with metal in an η⁵ mode. Complex <b>5</b> could also be prepared by reaction of [(Me₃Si)₂N]₃Nd­(μ-Cl)­Li­(THF)₃ with 3 equiv of <b>1</b>. Reactivities of the lanthanide bisamido complexes were further investigated. Reaction of complex <b>2</b> with pyrrolyl-functionalized imine [2-(2,6-^<i>i</i>Pr₂C₆H₃NCH)­C₄H₃NH] afforded a mixed η⁵-bonded neutral pyrrole and η¹-bonded anionic pyrrolyl lanthanum complex [η⁵:η¹-(<i>N</i>-C₆H₅NCH₂CH₂)­(2,5-Me₂C₄H₂N)]­{η¹-2-[(2,6-^<i>i</i>Pr₂C₆H₃)­NCH]­C₄H₃N}­La­[N­(SiMe₃)₂] (<b>6</b>). Reactions of complexes <b>2</b> and <b>3</b> with pyrrolyl-functionalized secondary amine afforded the mixed η⁵-bonded neutral pyrrole and the η¹-bonded anionic pyrrolyl lanthanide complexes [η⁵:η¹-(<i>N</i>-C₆H₅NCH₂CH₂)­(2,5-Me₂C₄H₂N)]­[(η¹-2-^<i>t</i>BuNCH)­C₄H₃N]₂Ln (Ln = La (<b>7</b>), Nd (<b>8</b>)) with dehydrogenation of the secondary amine. Investigation of the catalytic properties of complexes <b>2</b>–<b>8</b> indicated that all complexes exhibited a high activity with a high chemo- and regioselectivity on the addition of dialkyl phosphite to α,β-unsaturated carbonyl derivatives. An interesting result was found that 1,2-hydrophosphonylation substrates could be catalytically converted to 1,4-hydrophosphinylation products when the substrates are the substituted benzylideneacetones by controlling the reaction conditions

Synthesis and Reactivity of Rare-Earth-Metal Monoalkyl Complexes Supported by Bidentate Indolyl Ligands and Their High Performance in Isoprene 1,4-cis Polymerization

A series of novel rare-earth-metal monoalkyl complexes incorporating partially rotation restricted [N,N]-bidentate indolyl ligands were synthesized and characterized, and their reactivities and catalytic activities were investigated. Treatment of [RE­(CH₂SiMe₃)₃(thf)₂] with 1 equiv of 2-[(<i>N</i>-2,6-diisopropylphenyl)­iminomethyl)]­indole (2-(2,6-^<i>i</i>Pr₂C₆H₃NCH)­C₈H₅NH) in toluene at room temperature afforded the rare-earth-metal monoalkyl complexes [η¹:η¹-2-(2,6-^<i>i</i>Pr₂C₆H₃NCH)­Ind]₂RE­(CH₂SiMe₃)­(thf) (Ind = indolyl; RE = Yb (<b>1</b>), Er (<b>2</b>), Y (<b>3</b>), Dy (<b>4</b>), Gd (<b>5</b>)) and the samarium complex [η¹:η¹-2-(2,6-^<i>i</i>Pr₂C₆H₃NCH)­Ind]₃Sm (<b>6</b>) via alkane elimination in good yields. Treatment of complex <b>2</b> or <b>3</b> with 1 equiv of PhSiH₃ in toluene at 80 °C for 12 h afforded the dinuclear complexes {[μ-η⁶:η¹:η¹-2-(2,6-^<i>i</i>Pr₂C₆H₃NCH₂)­Ind]­RE­[2-(2,6-^<i>i</i>Pr₂C₆H₃NCH)­Ind]}₂ (Ind = indolyl, RE = Er (<b>7</b>), Y (<b>8</b>)) in good isolated yields. Treatment of complex <b>2</b> or <b>3</b> with 1 equiv of amidine (2,6-^<i>i</i>Pr₂C₆H₃)­NCHNH­(2,6-^<i>i</i>Pr₂C₆H₃) in toluene produced the corresponding complexes [η¹:η¹-2-(2,6-^<i>i</i>Pr₂C₆H₃NCH)­C₈H₅N]₂RE­[(2,6-^<i>i</i>Pr₂C₆H₃)­NCHN­(2,6-^<i>i</i>Pr₂C₆H₃)] (RE = Er (<b>9</b>), Y (<b>10</b>)) possessing the amidinate ligand [(2,6-^<i>i</i>Pr₂C₆H₃N)₂CH]⁻. The molecular structures of all complexes were determined by X-ray crystallography. The monoalkyl complexes <b>1</b>–<b>5</b> were tested as isoprene polymerization initiators. Among the complexes investigated, the optimum combination <b>5</b>/Al^<i>i</i>Bu₃/[Ph₃C]­[B­(C₆F₅)₄] displayed a high catalytic activity in isoprene polymerization, producing polymers with an extremely high 1,4-cis selectivity (up to 99%), a high number-average molecular weight (<i>M</i>_n = 7.2 × 10⁵), and a narrow molecular weight distribution (PDI = 1.34) at an isoprene to initiator molar ratio of 6000:1

Synthesis, Characterization, and Reactivity of Lanthanide Amides Incorporating Neutral Pyrrole Ligand. Isolation and Characterization of Active Catalyst for Cyanosilylation of Ketones

A series of lanthanide amido complexes incorporating a neutral pyrrole ligand were synthesized and characterized, and their catalytic activities were studied. Treatment of [(Me₃Si)₂N]₃­Ln­(μ-Cl)­Li­(THF)₃ with 1 equiv of [(2,5-Me₂C₄H₂N)­CH₂CH₂] ₂NH (<b>1</b>) in toluene afforded the corresponding lanthanide amides with the formula [η⁵:η¹-(2,5-Me₂C₄H₂N)­CH₂CH₂]₂­NLn­[N­(SiMe₃)₂]₂ (Ln = La (<b>2</b>), Nd (<b>3</b>)). Reaction of <b>2</b> or <b>3</b> with <i>N</i>,<i>N</i>′-dicyclo­hexyl­carbo­diimide (CyNCNCy) gave the carbodiimide selectively inserted into the appended Ln–N bond products formulated as CyNC­{[<i>N</i>,<i>N</i>-(2,5-Me₂C₄H₂N)­CH₂CH₂]₂N}­NCyLn­[N­(SiMe₃)₂]₂ (Ln = La (<b>4</b>), Nd (<b>5</b>)). Reactions of the lanthanide amides with Me₃SiCN were also examined. A mixed reaction of [(Me₃Si)₂N]₃­La­(μ-Cl)­Li­(THF)₃, [(2,5-Me₂C₄H₂N)­CH₂CH₂]₂NH (<b>1</b>), and Me₃SiCN in toluene at room temperature produced the novel cyano bridged dinuclear lanthanum complex η⁵:η¹:η³-[(2,5- Me₂C₄H₂N­CH₂CH₂)₂N]­La­[N­(SiMe₃)₂]­(μ-CN)­La­[N­(SiMe₃)₂]₃ (<b>6</b>). The stoichiometric reactions of lanthanide amides <b>2</b> or <b>3</b> with Me₃SiCN produced the novel trinuclear lanthanum and neodymium complexes {(η⁵:η¹-[(2,5-Me₂C₄H₂­NCH₂CH₂)₂N]­Ln­[N­(SiMe₃)₂]­(μ-CN)}₃ (Ln = La (<b>7</b>), Nd (<b>8</b>)) through selective σ-bond metathesis reaction of the terminal Ln–N (N­(SiMe₃)₂) bond with the Si–C bond of Me₃SiCN. On the basis of the stoichiometric reactions of complexes <b>2</b>, or <b>3</b> with Me₃SiCN, complexes <b>2</b>, <b>3</b>, <b>4</b>, <b>5</b>, <b>7</b>, and <b>8</b> as catalysts for cyanosilylation of ketones were investigated. Results indicated that these complexes displayed a high catalytic activity on addition of Me₃SiCN to ketones, and the activity of the complexes has the order of <b>7</b> ∼ <b>8</b> > <b>2</b> ∼ <b>3</b> ∼ <b>4 ∼ <b>5</b></b>. Thus, complex <b>7</b> or <b>8</b> was proposed as the active catalyst in the catalytic reaction for the precatalysts of <b>2</b> and <b>3</b>

Comprehensive Characterization of Organic Light-Emitting Materials in Breast Milk by Target and Suspect Screening

Organic light-emitting materials (OLEMs) are emerging contaminants in the environment and have been detected in various environment samples. However, limited information is available regarding their contamination within the human body. Here, we developed a novel QuEChERS (quick, easy, cheap, effective, rugged, and safe) method coupled with triple quadrupole/high-resolution mass spectrometry to determine OLEMs in breast milk samples, employing both target and suspect screening strategies. Our analysis uncovered the presence of seven out of the 39 targeted OLEMs in breast milk samples, comprising five liquid crystal monomers and two OLEMs commonly used in organic light-emitting diode displays. The cumulative concentrations of the seven OLEMs in each breast milk sample ranged from ND to 1.67 × 103 ng/g lipid weight, with a mean and median concentration of 78.76 and 0.71 ng/g lipid weight, respectively, which were higher compared to that of typical organic pollutants such as polychlorinated biphenyls and polybrominated diphenyl ethers. We calculated the estimated daily intake (EDI) rates of OLEMs for infants aged 0–12 months, and the mean EDI rates during lactation were estimated to range from 30.37 to 54.89 ng/kg bw/day. Employing a suspect screening approach, we additionally identified 66 potential OLEMs, and two of them, cholesteryl hydrogen phthalate and cholesteryl benzoate, were further confirmed using pure reference standards. These two substances belong to cholesteric liquid crystal materials and raise concerns about potential endocrine-disrupting effects, as indicated by in silico predictive models. Overall, our present study established a robust method for the identification of OLEMs in breast milk samples, shedding light on their presence in the human body. These findings indicate human exposure to OLEMs that should be further investigated, including their health risks

Synthesis and Reactivity of Rare-Earth-Metal Monoalkyl Complexes Supported by Bidentate Indolyl Ligands and Their High Performance in Isoprene 1,4-cis Polymerization

A series of novel rare-earth-metal monoalkyl complexes incorporating partially rotation restricted [N,N]-bidentate indolyl ligands were synthesized and characterized, and their reactivities and catalytic activities were investigated. Treatment of [RE­(CH₂SiMe₃)₃(thf)₂] with 1 equiv of 2-[(<i>N</i>-2,6-diisopropylphenyl)­iminomethyl)]­indole (2-(2,6-^<i>i</i>Pr₂C₆H₃NCH)­C₈H₅NH) in toluene at room temperature afforded the rare-earth-metal monoalkyl complexes [η¹:η¹-2-(2,6-^<i>i</i>Pr₂C₆H₃NCH)­Ind]₂RE­(CH₂SiMe₃)­(thf) (Ind = indolyl; RE = Yb (<b>1</b>), Er (<b>2</b>), Y (<b>3</b>), Dy (<b>4</b>), Gd (<b>5</b>)) and the samarium complex [η¹:η¹-2-(2,6-^<i>i</i>Pr₂C₆H₃NCH)­Ind]₃Sm (<b>6</b>) via alkane elimination in good yields. Treatment of complex <b>2</b> or <b>3</b> with 1 equiv of PhSiH₃ in toluene at 80 °C for 12 h afforded the dinuclear complexes {[μ-η⁶:η¹:η¹-2-(2,6-^<i>i</i>Pr₂C₆H₃NCH₂)­Ind]­RE­[2-(2,6-^<i>i</i>Pr₂C₆H₃NCH)­Ind]}₂ (Ind = indolyl, RE = Er (<b>7</b>), Y (<b>8</b>)) in good isolated yields. Treatment of complex <b>2</b> or <b>3</b> with 1 equiv of amidine (2,6-^<i>i</i>Pr₂C₆H₃)­NCHNH­(2,6-^<i>i</i>Pr₂C₆H₃) in toluene produced the corresponding complexes [η¹:η¹-2-(2,6-^<i>i</i>Pr₂C₆H₃NCH)­C₈H₅N]₂RE­[(2,6-^<i>i</i>Pr₂C₆H₃)­NCHN­(2,6-^<i>i</i>Pr₂C₆H₃)] (RE = Er (<b>9</b>), Y (<b>10</b>)) possessing the amidinate ligand [(2,6-^<i>i</i>Pr₂C₆H₃N)₂CH]⁻. The molecular structures of all complexes were determined by X-ray crystallography. The monoalkyl complexes <b>1</b>–<b>5</b> were tested as isoprene polymerization initiators. Among the complexes investigated, the optimum combination <b>5</b>/Al^<i>i</i>Bu₃/[Ph₃C]­[B­(C₆F₅)₄] displayed a high catalytic activity in isoprene polymerization, producing polymers with an extremely high 1,4-cis selectivity (up to 99%), a high number-average molecular weight (<i>M</i>_n = 7.2 × 10⁵), and a narrow molecular weight distribution (PDI = 1.34) at an isoprene to initiator molar ratio of 6000:1

Comprehensive Characterization of Organic Light-Emitting Materials in Breast Milk by Target and Suspect Screening

Organic light-emitting materials (OLEMs) are emerging contaminants in the environment and have been detected in various environment samples. However, limited information is available regarding their contamination within the human body. Here, we developed a novel QuEChERS (quick, easy, cheap, effective, rugged, and safe) method coupled with triple quadrupole/high-resolution mass spectrometry to determine OLEMs in breast milk samples, employing both target and suspect screening strategies. Our analysis uncovered the presence of seven out of the 39 targeted OLEMs in breast milk samples, comprising five liquid crystal monomers and two OLEMs commonly used in organic light-emitting diode displays. The cumulative concentrations of the seven OLEMs in each breast milk sample ranged from ND to 1.67 × 103 ng/g lipid weight, with a mean and median concentration of 78.76 and 0.71 ng/g lipid weight, respectively, which were higher compared to that of typical organic pollutants such as polychlorinated biphenyls and polybrominated diphenyl ethers. We calculated the estimated daily intake (EDI) rates of OLEMs for infants aged 0–12 months, and the mean EDI rates during lactation were estimated to range from 30.37 to 54.89 ng/kg bw/day. Employing a suspect screening approach, we additionally identified 66 potential OLEMs, and two of them, cholesteryl hydrogen phthalate and cholesteryl benzoate, were further confirmed using pure reference standards. These two substances belong to cholesteric liquid crystal materials and raise concerns about potential endocrine-disrupting effects, as indicated by in silico predictive models. Overall, our present study established a robust method for the identification of OLEMs in breast milk samples, shedding light on their presence in the human body. These findings indicate human exposure to OLEMs that should be further investigated, including their health risks

Synthesis of Bis(NHC)-Based CNC-Pincer Rare-Earth-Metal Amido Complexes and Their Application for the Hydrophosphination of Heterocumulenes

The bis­(NHC) (NHC = N-heterocyclic carbene)-based CNC-pincer rare-earth-metal amido complexes <b>L</b>RE­[N­(SiMe₃)₂]₂ (<b>L</b> = 4-CH₃-2-{R-[N­(CH)₂CN]}­C₆H₃]₂N; <b>L</b>^<b>2</b>, R = CH₃; <b>L</b>^<b>3</b>, R = CH­(CH₃)₂) were synthesized and characterized, and their catalytic activities toward hydrophosphination of heterocumulenes were developed. Reactions of bis­[2-(3-methylimidazolium)-4-methylphenyl]­amine diiodide (H₃<b>L</b>^<b>2</b>I₂) or bis­[2-(3-isopropylimidazolium)-4-methylphenyl]­amine diiodide (H₃<b>L</b>^<b>3</b>I₂) with 5 equiv of NaN­(SiMe₃)₂ followed by treatment with 1 equiv of RECl₃ in THF at −78 °C afforded the bis­(NHC)-based CNC-pincer rare-earth-metal amido complexes <b>L</b>RE­[N­(SiMe₃)₂]₂ (<b>L</b>^<b>2</b> = [4-CH₃-2-{CH₃-[N­(CH)₂CN]}­C₆H₃]₂N, RE = Y (<b>1</b>), Eu (<b>2</b>), Er (<b>3</b>); <b>L</b>^<b>3</b> = [4-CH₃-2-{(CH₃)₂CH-[N­(CH)₂CN]}­C₆H₃]₂N, RE = Y (<b>4</b>), Er (<b>5</b>), Yb (<b>6</b>)). Complexes <b>4</b>–<b>6</b> can also be prepared by stepwise reactions of H₃<b>L</b>^<b>3</b>I₂ with <i>n</i>-BuLi in THF followed by reactions with [(Me₃Si)₂N]₃RE­(μ-Cl)­Li­(THF)₃. Stepwise reactions of H₃<b>L</b>^<b>2</b>I₂ with <i>n</i>-BuLi in THF followed by treatment with [(Me₃Si)₂N]₃RE­(μ-Cl)­Li­(THF)₃ generated the bis­(NHC)-based CNC-pincer rare-earth-metal amido complexes <b>L</b>^<b>2</b>RE­[N­(SiMe₃)₂]₂ (RE = Y (<b>1</b>), Er (<b>3</b>)) together with the fused-heterocyclic compound 3,8,9-trimethyl-8a,9-dihydro-8<i>H</i>-benzo­[4,5]­imidazo­[2′,1′:2,3]­imidazo­[1,2-<i>a</i>]­imidazo­[2,1-<i>c</i>]­quinoxaline (<b>7</b>), which formed through carbene C–C and C–N coupling. Attempts to prepare complexes of the type <b>L</b>RE­[N­(SiMe₃)₂]₂ by reaction of H₃<b>L</b>^<b>3</b>I₂ with [(Me₃Si)₂N]₃Yb­(μ-Cl)­Li­(THF)₃ in THF, however, afforded mixed complexes of the bis­(NHC)-based CNC-pincer ytterbium complex <b>L</b>^<b>3</b>Yb­[N­(SiMe₃)₂]₂ (<b>6</b>) and the unexpected bis­(NHC)-based CNC-pincer monoamido ytterbium iodide <b>L</b>^<b>3</b>YbI­[N­(SiMe₃)₂] (<b>8</b>). Investigation of the catalytic activity of complexes <b>1</b>–<b>6</b> and <b>8</b> indicated that all complexes displayed high activity toward the addition of the phosphine P–H bond to heterocumulenes, producing the corresponding phosphaguanidines, phosphaureas, and phosphathioureas, which represents the first example of bis­(NHC)-based CNC-pincer type rare-earth-metal amido complexes as catalysts for the catalytic addition of the phosphine P–H bond to heterocumulenes with high efficiency in the presence of a low catalyst loading at room temperature

Synthesis and Characterization of Organolanthanide Complexes with a Calix[4]-pyrrolyl Ligand and Their Catalytic Activities toward Hydrophosphonylation of Aldehydes and Unactivated Ketones

The alkali metal salt free dinuclear trivalent lanthanide amido complexes (η⁵:η¹:η⁵:η¹-Et₈-calix­[4]-pyrrolyl)­{LnN­(SiMe₃)₂}₂ (Ln = Nd (<b>2</b>), Sm (<b>3</b>), Gd (<b>4</b>)) were prepared through the silylamine elimination reactions of calix[4]-pyrrole [Et₂C­(C₄H₂NH)]₄ (<b>1</b>) with 2 equiv of [(Me₃Si)₂N]₃Ln­(μ-Cl)­Li­(THF)₃ (Ln = Nd, Sm, Gd) in toluene at 110 °C. The complexes were fully characterized by elemental, spectroscopic, and single-crystal X-ray analyses. Studies on the catalytic activity of the new lanthanide amido complexes revealed that these complexes can be used as efficient catalysts for hydrophosphonylation of aldehydes and unactivated ketones, affording the products in high yields by employing a low catalyst loading (0.1 mol %) at room temperature in a short time (20 min). Noteworthy is that it is the first application of calix[4]-pyrrolyl-supported lanthanide amides as catalysts to catalyze the hydrophosphonylation of aldehydes and unactivated ketones under mild conditions