金属键

Other methyl nucleophiles includingMeMgBr, MeCeCl2, MeTiCl3, Me3Al, Me3ZnMgCl, MeMnClwere tried, but in all these cases no detectable amount of exo-C8-methylated product was obtained. Although protecting C3-carbonyl as 1,3-dioxolanes could be achieved, the serious enolization of C8-carbonyl was still problematic. Converting C9-furan ring to α,β-butenolide did depress the enolization, but desired C8-methylation was completely replaced by migration of the double bond of the butenolide.

在本论文的早期阶段，主要着眼于解决二环[3.2.1]-C8-羰基加成甲基所遇到的C9-呋喃环差向异构化和C3与C8两个羰基之间化学选择性的问题：通过引入不同金属降低甲基试剂的碱性并没有取得甲基化的成功；通过不同的方法将C3-羰基掩蔽，但是C8-羰基的烯醇化依然无法抑制；虽然通过将呋喃环转化为α，β-不饱和-γ-丁内酯可以抑制烯醇化，但内酯环上的双键迁移又成了新的竞争反应。

Fisher CV500 is a flanged or flangeless eccentric plug valve with reversible metal seat ring and splined shaft.

费希尔CV500是一个法兰或无法兰可逆金属座圈和花键

The hybrid composite PW11Co/PAMAM was characterized by FT-IR, UV-Vis diffuse reflectance spectra, XPS, XRD and TG/DTA, indicating that the PW11Co was chemically anchored to PAMAM. The morphologies of the title composite were characterized by scanning electron microscopy and transmission electron microscopy. The catalytic activity was evaluated by oxidation of isobutyraldehyde to isobutyric acid in MeCN under mild conditions (20 ℃, ambient pressure), showing that the title compound is a more effective and recoverable catalyst than corresponding PW11Co.

通过FT-IR、DR-UV-Vis、XRD、TEM、SEM、TG/DTA等手段对其进行了表征，并考察了其对异丁醛转化异丁酸的催化活性，实验结果表明，多金属氧酸盐通过配位键与聚酰胺-胺作用形成的无机-有机复合物可望成为一种催化活性高且易于分离和重复使用的多相催化剂。

The EE of metallics of Ti—Al system is studied in riew of bond structures and cleave energy, then the natural means and practical technology to improve EE are proposed.

也从键结构及解理能对Ti—Al系金属间化合物的环境脆性进行了探讨，提出了解决EE的根本途径及实际工艺。

The broken line in the formula represents a coordinate bond between a multidentate ligand and the metal.

在式中的虚线表示在多齿配体和金属之间的配位键。

Long-chain branched polyethylene was obtained using a homogeneous bianary catalyst system composed of late and early transition metal complexes,namely a mixture of bis(α-naphthalidine)-2,3-butanediimine NiBr2 and Cp* TiCl3,as catalyst precursors in the presence of MAO.

合成了一种后过渡金属镍化合物 [二- N ，N′--2 ，3-丁二亚胺镍二溴化物 ][C10H7—NC(CH3)C(CH3)N—C10H7]NiBr2，此化合物在MAO活化下催化乙烯聚合能得到含有末端双键的低分子量聚乙烯，即长链α-烯烃。

Coordination Chemistry: Characterization of the electronic structure and the bonding characteristic of nonplanar metalloporphyrins in different oxidation and spin states.

配位化学：探讨非平面金属在各种不同氧化态和自旋态之电子结构和键结特性。

The structure of the compound 〓(1) consists of a pentanuclear molecule which is center-symmetric. One W atom is coordinated by four S atoms and two Cu atom. As expected, the Fe atoms are sandwiched between two staggered pentadiene rings. The most interesting aspect of the structure is that Fe-C-P-Cu-P-Cconstitutes a distorted hexagon and Fe-Cu-W-Cu-Fe is nearly in a line.

结构是以W原子为对称中心含有五个金属原子的线型结构，W原子与四个μ〓-S和两个Cu原子配位；Fe原子在两个戊二烯环中间形成一个三明治夹心结构；Fe〓-C〓-P〓-Cu〓-P〓-C〓-构成扭曲的六边形，由于两边1，1'-双二茂铁配体的作用导致Cu-S键的拉长。

In this mechanism, a phosphine ligand in the Ru hydride complexes is replaced by protonic solvent ROH to generate the chain carrier.

三、反应机理论文提出，在固载Ru基催化剂上的scCO〓加H〓生成HCOOH的反应中，CO〓的活化在Ru配合物的作用下，以反插入Ru-H键，生成金属-羧酸配合物的形式进行。

The geometric and electronic structures of quadruply bonded metal dinuclear compounds M2Cl4(PMe3)4 (M=Cr, Mo, W) and Mo2X4(PMe3)4 (X=F, Cl, Br, I) have been investigated by means of density functional theory method with TZ2P-STO basis sets. It was shown that the title compounds can be accurately predicted by DFT included ZORA relativistic correction.

采用密度泛函理论方法，在TZ2P-STO基组水平下，对金属四重键化合物M2Cl4(PMe3)4 (M=Cr， Mo， W)和Mo2X4(PMe3)4 (X=F， Cl， Br， I)的几何结构进行优化，分析了电子结构，并运用TDDFT方法对其低占据激发态进行了计算。

According to the clear water experiment, aeration performance of the new equipment is good with high total oxygen transfer coefficient and oxygen utilization ratio.

曝气设备的动力效率在叶轮转速为120rpm～150rpm时取得最大值，此时氧利用率和充氧能力也具有较高值。

The environmental stability of that world - including its crushing pressures and icy darkness - means that some of its most famous inhabitants have survived for eons as evolutionary throwbacks, their bodies undergoing little change.

稳定的海底环境─包括能把人压扁的压力和冰冷的黑暗─意谓海底某些最知名的栖居生物已以演化返祖的样态活了万世，形体几无变化。