Synthesis,characterization, and theoretical studies of group 4 amido hydrotris(pyrazolyl)borate complexes

Titanium and zirconium amido complexes containing a hydrotris(pyrazolyl)borate (Tp) or hydrotris(3,5-dimethylpyrazolyl)borate (Tp*) ligand TpM(NMe(2))(3) (M = Ti, 1; M = Zr, 2) and Tp*M(NMe(2))(3) (M = Ti, 3; M = Zr, 4) were prepared by the reactions of M(NMe(2))(3)Cl (M = Ti, Zr) with sodium hydridotris(pyrazol-1-yl)borate and potassium hydridotris(3,5-dimethylpyrazol-1-yl)borate, respectively. The structures of 1, 2, and 4.CH(2)Cl(2) were determined by X-ray diffraction and show octahedral coordination geometry around the metal centers. Density functional theory calculations at the B3PW91 level were performed to understand the orientations and the rotational behavior of amido ligands in these metal complexes.     

丙烯酸甲酯/4-丙烯酰胺基-2,2,6,6-四甲基哌啶光共聚合体系的竞聚率和序列分布研究

以丙烯酸甲酯(MA,M1)和4-丙烯酰胺基-2,2,6,6-四甲基哌啶(AATP,M2)溶液光共聚合体系为研究对象,采用1H-NMR手段测定了MA/AATP共聚物的组成,用Mayo-Lewis积分法和扩展Kelen-Tüdos方法计算的竞聚率分别为0.88相似文献   

热变形奥氏体静态再结晶行为的研究

本文利用双道次压缩的方法,在Gleeble1500热模拟实验机上研究了低碳钢SS400在变形间隔时间内奥氏体的软化行为,以便为制定合理的细化晶粒轧制工艺提供实验和理论基础.采用后插法计算了在不同真应变条件下的静态再结晶率.通过双道次压缩测试静态软化动力学实验的表明,实验钢变形后很容易发生静态软化.在真应变为0.4,0.2时,静态再结晶激活能分别是Qrec=189.3,179.2kJ/mol.     

Remarkably efficient oxidative coupling of N,N-dialkylarylamines in water mediated by cerium(IV) ammonium nitrate

A highly effective, economical, and environmentally friendly method using of CAN as oxidant and water as solvent for oxidative coupling of N,N-dialkylarylamines was reported.     

Preparation of α-amino acids via Ni-catalyzed reductive vinylation and arylation of α-pivaloyloxy glycine

This work emphasizes easy access to α-vinyl and aryl amino acids via Ni-catalyzed cross-electrophile coupling of bench-stable N-carbonyl-protected α-pivaloyloxy glycine with vinyl/aryl halides and triflates. The protocol permits the synthesis of α-amino acids bearing hindered branched vinyl groups, which remains a challenge using the current methods. On the basis of experimental and DFT studies, simultaneous addition of glycine α-carbon (Gly) radicals to Ni(0) and Ar–Ni(ii) may occur, with the former being more favored where oxidative addition of a C(sp²) electrophile to the resultant Gly–Ni(i) intermediate gives a key Gly–Ni(iii)–Ar intermediate. The auxiliary chelation of the N-carbonyl oxygen to the Ni center appears to be crucial to stabilize the Gly–Ni(i) intermediate.

We have developed Ni-catalyzed reductive coupling of N-carbonyl protected α-pivaloyloxy glycine with Csp²-electrophiles that enabled facile preparation of α-amino acids, including those bearing hindered branched vinyl groups.     

Reactions of d0 group 4 amides with dioxygen. Preparation of unusual oxo aminoxy complexes and theoretical studies of their formation

Reactions of d0 amides M(NMe2)4 (M = Zr, 1; Hf, 2) with O2 have been found to yield unusual trinuclear oxo aminoxide complexes M3(NMe2)6(mu-NMe2)3(mu3-O)(mu3-ONMe2) (M = Zr, 3; Hf, 4) in high yields. Tetramethylhydrazine Me2N-NMe2 was also observed in the reaction mixtures. Crystal structures of 3 and 4 have been determined. Density functional theory calculations have been performed to explore the mechanistic pathways in the reactions of model complexes Zr(NR2)4 (R = H, 5; Me, 1) and [Zr(NR2)4]2 (R = H, 5a; Me, 1a) with triplet O2. Monomeric and dimeric reaction pathways in the formation of the Zr complex 3 are proposed.     

Oxidative Coupling Reaction of N,N‐Dialkylanilines with Cerium(IV) Ammonium Nitrate in the Solid State

Oxidative coupling reactions of N,N‐dialkylanilines with cerium(IV) ammonium nitrate can be achieved by grinding at room temperature in the absence of solvents.     

A ratiometric near-infrared naphthalimide-based fluorescent probe with high sensitivity for detecting Fe2+ in vivo

Iron is one of the essential trace elements in the human body. It plays an important role in human biology and pathology. Deregulation of iron levels in cells is associated with disease development. In this work, we synthesized a novel near-infrared intramolecular charge transfer (ICT) based ratiometric fluorescent probe to detect Fe²⁺, by using naphthalimide and indole moieties as building blocks. Our work showed that the radiometric probe has excellent selectivity, sensitivity and rapid response. Moreover, we could successfully perform real-time monitoring of Fe²⁺ in HeLa cells and C. elegans.