Insertion reactions of hydridonitrosyltetrakis(trimethylphosphine) tungsten(0)

[W(H)(NO)(PMe3)4] (1) was prepared by the reaction of [W(Cl)(NO)(PMe3)4] with NaBH4 in the presence of PMe3. The insertion of acetophenone, benzophenone and acetone into the W-H bond of 1 afforded the corresponding alkoxide complexes [W(NO)(PMe3)4(OCHR1R2)](R1 = R2 = Me (2); R1 = Me, R2 = Ph (3); R1 = R2 = Ph (4)), which were however thermally unstable. Insertion of CO2 into the W-H bond of yields the formato-O complex trans-W(NO)(OCHO)(PMe3)4 (5). Reaction of trans-W(NO)(H)(PMe3)4 with CO led to the formation of mer-W(CO)(NO)(H)(PMe3)3 (6) and not the formyl complex W(NO)(CHO)(PMe3)4. Insertion of Fe(CO)(5), Re2(CO)10 and Mn2(CO)10 into trans-W(NO)(H)(PMe3)4 resulted in the formation of trans-W(NO)(PMe3)4(mu-OCH)Fe(CO)4 (7), trans-W(NO)(PMe3)4(mu-OCH)Re2(CO)9 (8) and trans-W(NO)(PMe3)4(mu-OCH)Mn2(CO)9 (9). For Re2(CO)10, an equilibrium was established and the thermodynamic data of the equilibrium reaction have been determined by a variable-temperature NMR experiments (K(298K)= 104 L mol(-1), DeltaH=-37 kJ mol(-1), DeltaS =-86 J K(-1) mol(-1)). Both compounds 7 and 8 were separated in analytically pure form. Complex 9 decomposed slowly into some yet unidentified compounds at room temperature. Insertion of imines into the W-H bond of 1 was also additionally studied. For the reactions of the imines PhCH=NPh, Ph(Me)C=NPh, C6H5CH=NCH2C6H5, and (C6H5)2C=NH with only decomposition products were observed. However, the insertion of C10H7N=CHC6H5 into the W-H bond of led to loss of one PMe3 ligand and at the same time a strong agostic interaction (C17-H...W), which was followed by an oxidative addition of the C-H bond to the tungsten center giving the complex [W(NO)(H)(PMe3)3(C10H6NCH2Ph)] (10). The structures of compounds 1, 4, 7, 8 and 10 were studied by single-crystal X-ray diffraction.     

Poly[[diaquamanganese(II)]‐μ3‐4‐oxido‐2‐oxo‐1,2‐dihydropyrimidine‐5‐carboxylato‐κ4O4,O5:O2:O2]

In the title compound, [Mn(C₅H₂N₂O₄)(H₂O)₂]_n, the Mn^II ion has a distorted octahedral geometry and the 4‐oxido‐2‐oxo‐1,2‐dihydropyrimidine‐5‐carboxylate (Hiso²⁻) anion acts as a μ₃:η⁴‐bridging ligand. Two oxo O atoms from different Hiso²⁻ ligands bridge two Mn^II ions, forming centrosymmetric dinuclear building blocks. Each dinuclear building block interacts with another four by the coordination of the oxide groups and carboxylate O atoms, producing a two‐dimensional framework in the ab plane. Hydrogen bonds further extend the two‐dimensional sheets into a three‐dimensional supramolecular framework.     

Thermal and optical properties of highly fluorinated copolymers of methacrylates

Copolymers of pentafluorophenylhexafluoroisopropyl methacrylate (FPPMA) with trifluoroethyl methacrylate (TFEMA) were prepared in THF solution and in bulk using azobisisobutyronitrile as a free radical initiator. The monomer reactivity ratios of TFEMA (M₁) and FPPMA (M₂) were calculated as r₁ = 0.55 and r₂ = 0.07. The refractive indices of poly(TFEMA) and poly(FPPMA) are very similar as 1.435 and 1.430, respectively, at 532 nm, and the copolymer films were transparent. The glass transition temperatures (T_g) of the copolymers were in the range of 80–90°C and showed a negative deviation from the Gordon–Taylor equation. The thermal decomposition temperature (T_d) was increased with the content of FPPMA in copolymers. Low water absorption for 1:1 FPPMA/TFEMA copolymer was detected. Copolymers of FPPMA with hexafluoroisopropyl methacrylate (HFPMA) were also prepared. The monomer reactivity ratios of HFPMA (M₁) and FPPMA (M₂) were calculated as r₁ = 0.43 and r₂ = 0.10. The T_gs of the copolymers were in the range of 88–95°C and showed also a negative deviation from the Gordon–Taylor equation. T_g and T_d of the copolymers were increased with the content of FPPMA. The refractive index of poly(HFPMA) (1.384 at 532 nm) is much lower than that of FPPMA homopolymer, but copolymer films obtained were clear and transparent. Copyright © 2013 John Wiley & Sons, Ltd.     

Synthesis,Structure, and Magnetic Properties of a Series of Dinuclear Lanthanide Complexes Assembled by Acetate and a Schiff Base Ligand

Five dinuclear lanthanide complexes [Ln₂L₂(NO₃)₂(OAc)₄] · 2CH₃CN [Ln = Gd ( 1 ), Tb ( 2 ), Dy ( 3 ), Ho ( 4 ), and Er ( 5 )] [L = 2‐((2‐pyridinylmethylene)hydrazine)ethanol] were synthesized from the reactions of Ln(NO₃)₃ · 6H₂O with L and CH₃COOH in the presence of triethylamine. Their crystal structures were determined. They show similar dinuclear cores with the two lanthanide ions bridged by four acetate ligands in the μ₂‐η¹:η² and μ₂‐η¹:η¹ bridging modes. Each Ln^III ion in complexes 1 – 5 is further chelated by one L ligand and one nitrate ion, leading to the formation of a nine‐coordinated mono‐capped square antiprism arrangement. The dinuclear molecules in 1 – 5 are consolidated by hydrogen bonds and π ··· π stacking interactions to build a two‐dimensional sheet. Their magnetic properties were investigated. It revealed antiferromagnetic interactions between the Gd^III ions in 1 and ferromagnetic interactions between the Tb^III ions in 2 . The profiles of χ_mT vs. T curves of 3 – 5 reveal that the magnetic properties of 3 – 5 are probably dominated by the thermal depopulation of the Stark sublevels of Ln^III ions.     

Structure and Magnetic Properties of Two Lanthanide 1,4‐Phenylenediacetate Compounds

The reactions of Ln(NO₃)₃ with 1,4‐phenylenediacetic acid (H₂PDA) under hydrothermal conditions produced two isostructural lanthanide coordination polymers with the empirical formula [Ln₂(PDA)₃(H₂O)] · 2H₂O [Ln = Nd ( 1 ), Sm ( 2 )]. Single‐crystal X‐ray diffraction analyses revealed that both contain one‐dimensionalmetal carboxylato chains, which are further connected by the–CH₂C₆H₄CH₂– spacers of PDA^2– ligands to yield a three‐dimensional metal‐organic framework. Magnetic susceptibilities of 1 and 2 were measured. The experimental χ_mT value of both compounds decreases continuously with decreasing temperature over the whole temperature range. The best least‐squares fit of the experimental data of 1 to a theoretical equation in the temperature range of 70–300 K gives the zero‐field splitting parameter Δ = 2.21 cm^–1 and the magnetic interaction between the Nd^III ions 2zJ′ = –1.97 cm^–1, which indicates the presence of antiferromagnetic interaction between the Nd^III ions. The experimental χ_mT value of 2 at 2 K is much smaller than the expected value for two free Sm^III ions (⁶H_5/2, g = 2/7) in the ground state, indicating that an antiferromagnetic interaction possibly exists between Sm^III ions at low temperature. Fitting the magnetic data of 2 above 110 K based on an equation deduced from the Sm^III ion in a monomeric system with free‐ion approximation gave a spin‐orbit coupling parameter λ = 192(2) cm^–1     

Four Zn(II)/Cd(II)-3-amino-1,2,4-triazolate frameworks constructed by in situ metal/ligand reactions: Structures and fluorescent properties

Four Cd(II) and Zn(II) complexes with the in situ-generated ligand of 3-amino-1,2,4-triazolate (AmTAZ⁻) were isolated from the solvothermal reactions of the corresponding Cd(II) or Zn(II) salts with 5-amino-1H-1,2,4-triazole-3-carboxylic acid (AmTAZAc). Their structures were determined by single-crystal X-ray diffraction analysis. [Zn(AmTAZ)(CH₃COO)] (1) presents a two-dimensional framework constructed from Zn(II) ions and μ₃-AmTAZ⁻ ligands. A remarkable feature of [Zn₄(AmTAZ)₄(SO₄)(OH)(C₂O₄)_0.5]·2H₂O (2) is the construction of the building units of octagonal cylinders which interact with each other by sharing one face or overlapping, resulting in the formation of a three-dimensional framework with three kinds of 1D channels. [Cd(AmTAZ)Br] (3) crystallizes in a chiral space group P2₁2₁2₁, giving a homochiral three-dimensional framework with two types of helical channels (left- and right-handed). Different from the others, the 3-amino-1,2,4-triazole molecules in [Cd(AmTAZH)SO₄] (4) behave as neutral μ₂-2,4-bridges to connect the two-dimensional CdSO₄ sheets into a three-dimensional framework. Of all, 2 and 3 display different fluorescent properties probably due to different metal ions, coordination environments and structural topologies.     

用于飞秒紫外激光产生的LD泵浦高效Nd:YVO4绿光激光器研究

利用简单的折叠腔,腔内不含任何其它附加光学元件,LD双端泵浦Nd:YVO₄,KTP腔内倍频绿光激光器实现了低阈值、高效率的TEM₀₀模稳定激光输出.最高绿光输出功率可达到3.3W,光-光转换效率为16.2%.     

用边界元素法模拟FP-JTE终端结构

提出了一种无须进行电离积分的用于高压结终端模拟的边界元素法,分析了界面电荷对FP-JTE终端结构击穿电压的影响,结果表明击穿电压几乎与界面电荷浓度呈线性关系,场板可减弱界面电荷对击穿电压的影响。     

A three‐dimensional homochiral metal–organic framework constructed from manganese(II) with S‐carboxymethyl‐N‐(p‐tosyl)‐l‐cysteine and 4,4′‐bipyridine

In the chiral polymeric title compound, poly[aqua(4,4′‐bipyridine)[μ₃‐S‐carboxylatomethyl‐N‐(p‐tosyl)‐l ‐cysteinato]manganese(II)], [Mn(C₁₂H₁₃NO₆S₂)(C₁₀H₈N₂)(H₂O)]_n, the Mn^II ion is coordinated in a distorted octahedral geometry by one water molecule, three carboxylate O atoms from three S‐carboxyatomethyl‐N‐(p‐tosyl)‐l ‐cysteinate (Ts‐cmc) ligands and two N atoms from two 4,4′‐bipyridine molecules. Each Ts‐cmc ligand behaves as a chiral μ₃‐linker connecting three Mn^II ions. The two‐dimensional frameworks thus formed are further connected by 4,4′‐bipyridine ligands into a three‐dimensional homochiral metal–organic framework. This is a rare case of a homochiral metal–organic framework with a flexible chiral ligand as linker, and this result demonstrates the important role of noncovalent interactions in stabilizing such assemblies.