Shin-Guang Shyu

A copper(II) complex as an intermediate of copper(I)-catalyzed C-N cross coupling of N-phenylaniline with aryl halide by in situ ESI-MS study.

Complexes [Cu(NPh(2))(2)](-), [Cu(NPh(2))I](-) and K[Cu(phen)(NPh(2)) (p-tolyl)](+) were observed by in situ electrospray ionization mass spectrometry (ESI-MS) analysis of the copper(I)-catalyzed C-N coupling reaction under the catalytic reaction condition indicating that they are intermediates in the reaction. A catalytic cycle composed of a free radical path and a 2e oxidative addition path is proposed based on these observations.

Copper(I)–Anilide Complex [Na(phen)3][Cu(NPh2)2]: An Intermediate in the Copper‐Catalyzed N‐Arylation of N‐Phenylaniline

Complex [Na(phen)(3)][Cu(NPh(2) )(2)](2), containing a linear bis(N-phenylanilide)copper(I) anion and a distorted octahedral tris(1,10-phenanthroline)sodium counter cation, has been isolated from the catalytic C-N cross-coupling reaction with the CuI/phen/tBuONa (phen=1,10-phenanthroline) catalytic system. Complex 2 can react with 4-iodotoluene to produce 4-methyl-N,N-diphenylaniline (3 a) with 70.6 % yield. In addition, 2 can work as an effective catalyst for C-N coupling under the same reaction conditions, thus indicating that 2 is the intermediate of the catalytic system. Both [Cu(NPh(2))(2)](-) and [Cu(NPh(2))I](-) have been observed by in situ electron ionization mass spectrometry (ESI-MS) under catalytic reaction conditions, thus confirming that they are intermediates in the reaction. A catalytic cycle has been proposed based on these observations. The molecular structure of 2 has been determined by single-crystal X-ray diffraction analysis.

High frequency impedance spectra on the chromium dioxide thin film

We report on the study of high frequency magnetotransport properties of the chromium dioxide (CrO2) thin films, grown on Si substrate using chemical vapor deposition. The film exhibits a ferromagnetic transition with a Curie temperature near 390 K. The temperature dependent spontaneous magnetization follows Bloch’s law. The impedance spectra, being analyzed based on the fundamental electrodynamics, are demonstrated to be in a low-loss dielectric limit along with the occurrence of dielectric relaxation and magnetization response. The specific features of impedance spectra, distinct from the usual metallic ferromagnet, are attributed to the half metallic nature of CrO2. The results explore the possibility for high frequency device applications.

Efficient and selective copper-catalyzed organic solvent-free and biphasic oxidation of aromatic gem-disubstituted alkenes to carbonyl compounds by tert-butyl hydroperoxide at room temperature

Copper-catalyzed alkene oxidation to carbonyl compounds by tert-butyl hydroperoxide (TBHP) under organic solvent-free and biphasic conditions at room temperature is selective for the aromatic gem-disubstituted alkenes. Enhanced reactivity was observed in the presence of 2,9-dimethyl-1,10-phenanthroline (neocuproine). The reaction is economically attractive because the yield is high, and separation of products and recycling of the catalyst are easy.

Synthesis and Structure of Heterobimetallic Compounds with a Single Thiolato‐Bridged Ligand

Reactions between CpFe(CO)2SPh and M(CO)5THF (M = Cr, Mo, and W) in a mixture of benzene and THF at room temperature afforded compounds of the type CpFe(CO)2(μ-SPh)M(CO)5 (1) [M = Cr (1a), Mo (1b), and W (1c)] in high yield. However, migration of the thiolato ligand occurred during reactions between CpM(CO)xSPh (M = Fe, x = 2; M = Mo and W, x = 3) and Fe2(CO)9 forming compounds [Fe(μ-SPh)(CO)3]2 and [CpM(CO)x]2 (M = Fe, x = 2; M = Mo and W, x = 3). Single-crystal X-ray diffraction analyses reveal that 1c is a single thiolato-bridged hererobimetallic compound without a metal−metal bond. Metal−metal bond formation in compounds 1 by decarbonylation under thermal or photolytic condition was not observed. Reactions between compounds 1 and PPh3 produced CpFe(CO)2SPh and PPh3M(CO)5 (M = Cr, Mo, and W) by M−S bond cleavage in 1.

Immobilization of Rh(PPh3)3Cl on phosphinated MCM-41 for catalytic hydrogenation of olefins

The complex Rh(PPh3)3Cl immobilized on MCM-41 modified with (OEt)3Si(CH2)3PPh2 results in a stable hydrogenation catalyst with turnover frequency (TOF) three times higher than that of Rh(PPh3)3Cl in the hydrogenation of cyclohexene.

Synthesis, structure and substitution reactions of the binuclear phosphido-bridged complex

Abstract Bimetallic phosphido-bridged complexes CpW(CO) 3 (μ-PPh 2 )W(CO) 5 ( 1 ) and Cp W(CO) 2 (μ- PPh 2 W ( Co ) 5 ( 2 ) were prepared by the reaction of CpW(CO) 3 PPh 2 with W(CO) 5 THF. The structures of 1 and 2 were determined by single X-ray diffraction. Crystal data for 1 : C 25 H 15 O 8 PW 2 , space group, P2 1 /n with a = 9.6234 (18) A , b = 12.4514 (20) A , c = 20.750 (4) A , β = 98.445 (14)°, V = 2459.4 (7) A 3 , Z = 4 . The structure was refined to R = 0.031 and R W = 0.035. Crystal data for 2 : C 24 H 15 O 7 PW 2 , space group, P2 1 /n with a = 14.4801 (11) A , b = 11.6628 (12) A , c = 14.732 (3) A , β = 97.893 (11)°, V = 2464.3 (6) A 3 , Z = 4 . The structure was refined to R = 0.054 and R W = 0.050. The long distance between W and W (4.5096 (11) A) in 1 indicates that no metal-metal bond exists in the complex. The W-W distance was 3.1942 (12) A in 2 , indicative of a W-W bond. Substitution reactions between 2 and Lewis bases L (L = PPh 3 , PEt 3 , P(OMe) 3 ) produced Cp W(CO) 2 (μ- PPh 2 W ( CO ) 4 ( L ) ( 3 ) with L regiospecifically and stereospecifically coordinating to the W(CO) 4 moiety trans to the phosphido bridge. The structure of Cp W(CO) 2 (μ- PPh 2 W ( CO ) 4 { P (OMe) 3 } ( 3a ) was determined by single-crystal X-ray diffraction. Crystal data for 3a : C 26 H 24 O 9 P 2 W 2 , space group, P2 1 with a = 9.2231 (16) A , b = 15.868 (3) A , c = 10.745 (3) A , β = 110.282 (18)°, V = 1475.1 (5) A 3 , Z = 2 . The structure was refined to R = 0.037 and R W = 0.039. Under similar reaction conditions, complex 1 did not react with L.

Synthesis and properties of mixed-metal phosphido and phosphinidene clusters derived from reaction between Ru3(CO)10(μ-H)(μ-PPh2) and Cp★ Mo(CO)3H

Abstract The tetranuclear phosphido cluster Cp ★ MoRu 3 (CO) 10 (μ-H) 2 (μ-PPh 2 ) ( 5 ) and the phosphinidene cluster Cp ★ MoRu 3 (CO) 10 (μ 3 -H) (μ 3 -PPh) ( 6 ) have been synthesized by reaction of Ru 3 (CO) 10 (μ-H)(μ-PPh 2 ) with excess molybdenum hydride Cp ★ Mo(CO) 3 H in refluxing toluene solution. Crystals of 5 are monoclinic, space group P 2 1 with a = 10.708(2), b = 10.848(4), c = 14.885(2) A, β = 97.63(2)°, Z = 2, R = 0.021, R w = 0.019 for 3025 observed reflections. The cluster has a tetrahedral array of metal atoms with one edge-bridging and one face-bridging hydride, and a phosphido ligand bridged across a basal Ru-Ru edge. Thermolysis of 5 under similar conditions produced the phosphinidene cluster 6 in high yield via elimination of a benzene molecule, indicating that 5 is an intermediate in the formation of 6 . Subsequent treatment of 6 with CO caused fragmentation of the cluster affording a trinuclear phosphinidene cluster Cp ★ MoRu 2 (CO) 8 (μ-H)(μ 3 -PPh) ( 7 ). Dimerization of 7 occurred upon thermolysis to afford hexanuclear Cp 2 ★ Mo 2 Ru 4 (CO) 12 (μ-PPh) 2 ( 8 ), which has also been characterized by X-ray diffraction. Crystal data of 8 : space group C 2/c ; a = 45.333(7), b = 10.185(2), c = 21.915(8) A, β = 93.82(3)°, Z = 8. The structure was solved by direct method and refined to R and R w of 0.035 and 0.030 for 6135 observed reflections with I > 2σ-( I ). The molecule adopts a square pyramidal MoRu 4 skeleton with a tentacle Mo atom bridging a Ru-Ru edge, on which the novel μ 4 -η 2 -CO ligand is associated with the butterfly Mo 2 Ru 2 array; one μ 4 -PPh ligand occupies a MoRu 3 square face and a second μ 3 -PPh ligand caps a MoRu 2 face.

Structures and Mössbauer spectra of phosphido-bridged heterobimetallic complexes CpFe(CO)2(μ-PPh2)W(CO)5 and CpFe(CO)(μ-CO)(μ-PPh2)W(CO)4

Abstract Structures of non metal-metal bonded phosphido-bridged heterobimetallic complexes, including CpFe(CO) 2 (μ-PPh 2 )W(CO) 5 ( 1 -W) and metal-metal bonded CpFe(CO)(μ-CO)(μ-PPh 2 )W(CO) 4 ( 2 ), were determined by a single crystal X-ray diffraction study. In 1 -W, the long distance between Fe and W indicates no metal-metal bond to exist. In 2 , a FeW bond with bond length 2.851 A and a semibridging carbonyl with WCO angle 153° were observed. Mossbauer spectra of 1 -W and 2 were taken at 77 K. Isomer shifts of 1 -W and 2 were − 0.0203 mm s −1 and 0. 1917 mm s −1 respectively.

Characterization of magnetoimpedance on polycrystalline and amorphous chromium oxides bilayered thin films

The impedance of chemical vapor deposited CrO2 and Cr2O3 bilayered thin films, composed of polycrystalline and amorphous structure, have been systematically studied in function of frequency and temperature. In the polycrystalline-CrO2/amorphous-Cr2O3 bilayer, the real part of impedance at low frequency (f 300 kHz, shows a characteristic of negative temperature coefficient. Further analysis of the frequency dependence of the impedance shows the contribution from the dynamics of both the dielectric and magnetic dipoles in the layers. Comparison of polycrystalline-CrO2 and amorphous-Cr2O3 single layer with the CrO2/Cr2O3 bilayer is discussed.