Four amidate-functionalized N-heterocyclic carbene (NHC) rare-earth metal amido complexes [(κ 2 -N,O-κ 1 -L) 2 REN(SiMe 3 ) 2 ] (L = 1-(C 6 H 5 CONCH 2 CH 2 )-3-(CH 3 ) 3 C 6 H 2 (N(CH) 2 NC)) [RE = Er (1), Y (2), Dy (3), Gd (4)] were synthesized by one-pot reactions of 2 equiv of (1-(C 6 H 5 CONHCH 2 CH 2 )-3-(CH 3 ) 3 C 6 H 2 -(N(CH) 2 NCH))Br (H 2 LBr) with 5 equiv of KN(SiMe 3 ) 3 followed by treatment with 1 equiv of RECl 3 in tetrahydrofuran at −40 °C. These complexes were fully characterized, and their catalytic activities toward hydroboration of unactivated imines and nitriles were investigated, and it was found that these complexes displayed excellent activities as well as remarkable functional group compatibility for imine and nitrile substrates such as halo-, alkyl-, hydroxyl-, N,N-dimethylamino-, and nitro-substituents. Among those, the chemoselectivity for this reaction among the common unsaturated functional groups was achieved in the order CO ≫ CN > CN > CO 2 Et > CC in the current catalytic system, which may facilitate their further application in synthetic chemistry.

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A series of aluminum complexes with Schiff base bridged indolyl ligands were synthesized as rac-lactide polymerization catalysts.

cannot endow the SQD with enough stability. The prepared SQDs generally exhibit poor optical stability, limiting their down-to-earth applicability. For example, the fluorescent intensity of PEG-capped SQDs declined by 48% after exposure to UV lamp for 10 min. [4] In this context, it is very important and urgent to develop a simple and effective approach to enhance the optical stability of SQDs.As a kind of essential trace ion in organism, Fe 3+ plays an important role in numerous metabolic processes, such as enzyme catalysis, oxygen exchange, and transport. [13] Excessive or deficiency of Fe 3+ may result in a series of diseases (e.g., heart failure and anemia), and thus monitoring of Fe 3+ is quite meaningful for early clinical diagnosis. [14] On the other hand, temperature is a critical physical parameter that can affect the behavior of chemical and biological systems. Hence, the development of temperature sensor to monitor temperature in diverse environments especially in biosystem is highly needed. Among various technologies for monitoring of Fe 3+ or temperature, much attention has been paid on fluorescence detection because of its advantages of facile sample treatment process, superior sensitivity, rapid response, noninvasiveness, and low cost. [15,16] In recent years, a variety of fluorescent materials such as semiconductor quantum dots, silicon nanocrystals, metal nanoclusters, organic dyes, conjugated polymers, and carbon dots have been developed to detect Fe 3+ or temperature. [17][18][19][20][21][22][23][24] Unfortunately, most of them are either toxic or suffer from poor stability and high cost, which seriously hinders their practical applications. In addition, many fluorescent materials exhibit poor aqueous solubility or dispersibility, so their ability to detect Fe 3+ or temperature in biological environment (e.g., cells) is greatly limited. Therefore, the rational design and preparation of desired fluorescent probes to detect Fe 3+ or temperature in biological environment remain a challenge and is valuable.In this contribution, we attempt to utilize water-soluble and biocompatible polyvinyl alcohol (PVA) as ligand for fabricating fluorescent SQDs (Figure 1). PVA was carefully chosen because each PVA macromolecule contains a number of lateral hydroxyl groups, which can provide strong affinity interaction with the surface of formed SQDs to enhance the stability of SQDs. On the other hand, there is a strong complex interaction between As a new class of metal-free fluorescent dots, sulfur quantum dots (SQDs) have attracted more and more attention because of their unique properties and promising applications in many fields. However, synthesizing SQDs with high optical stability and stimuli-responsive fluorescence is still in its infancy. Herein, a simple one-pot strategy is reported for preparing polyvinyl alcohol (PVA)-capped SQDs from cheap elemental sulfur by employing PVA as ligand. The as-prepared SQDs with size in range of 1.5-5 nm show fine water dispersibility and stability, bright fluorescence,...

The bis­(NHC) (NHC = N-heterocyclic carbene)-based CNC-pincer rare-earth-metal amido complexes LRE­[N­(SiMe3)2]2 (L = 4-CH3-2-{R-[N­(CH)2CN]}­C6H3]2N; L 2 , R = CH3; L 3 , 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 L 2 I2) or bis­[2-(3-isopropylimidazolium)-4-methylphenyl]­amine diiodide (H3 L 3 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 LRE­[N­(SiMe3)2]2 (L 2 = [4-CH3-2-{CH3-[N­(CH)2CN]}­C6H3]2N, RE = Y (1), Eu (2), Er (3); L 3 = [4-CH3-2-{(CH3)2CH-[N­(CH)2CN]}­C6H3]2N, RE = Y (4), Er (5), Yb (6)). Complexes 4–6 can also be prepared by stepwise reactions of H3 L 3 I2 with n-BuLi in THF followed by reactions with [(Me3Si)2N]3RE­(μ-Cl)­Li­(THF)3. Stepwise reactions of H3 L 2 I2 with n-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 L 2 RE­[N­(SiMe3)2]2 (RE = Y (1), Er (3)) together with the fused-heterocyclic compound 3,8,9-trimethyl-8a,9-dihydro-8H-benzo­[4,5]­imidazo­[2′,1′:2,3]­imidazo­[1,2-a]­imidazo­[2,1-c]­quinoxaline (7), which formed through carbene C–C and C–N coupling. Attempts to prepare complexes of the type LRE­[N­(SiMe3)2]2 by reaction of H3 L 3 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 L 3 Yb­[N­(SiMe3)2]2 (6) and the unexpected bis­(NHC)-based CNC-pincer monoamido ytterbium iodide L 3 YbI­[N­(SiMe3)2] (8). Investigation of the catalytic activity of complexes 1–6 and 8 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.

The first heterobimetallic Pd−Sc complex featuring a very short Pd→Sc dative bond has been synthesized and characterized by multinuclear NMR spectroscopy, X‐ray diffraction analysis, and electrochemistry. Computational studies elucidated the nature of the Pd→Sc bond as a donor–acceptor interaction, which generates a more electron‐deficient Pd0 metal center as compared to that in the mono Pd0 complex in their reactions with isonitrile and carbon monoxide. Cooperative reactivity has been demonstrated in the reaction with MeI.