Browsing by Author "PENG, SM"

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A NOVEL SYNTHESIS OF ORGANOIMIDO COMPLEX BY TRANSAMINATION REACTION - X-RAY CRYSTAL-STRUCTURE OF BIS-(ISOPROPYLIMIDO) COMPLEX OF TUNGSTEN(VI), [W(MU-NPRI)(NPRI)(NHPRI)2]2
(1994-08-01)
CHIU, HT
;
CHUANG, SH
;
LEE, GH
;
PENG, SM
;
應用化學系
The bis(isopropylimido) complex [W(mu-NPri)(NPri) (NHPri)(2)](2) was synthesized by reacting W-2(NBu(i))(2)(NHBu(i))(2) with excess (PrNH2)-N-i. The complex, characterized by X-ray crystallography, is a dimer of distorted trigonal bipyramids sharing an edge defined by the unsymmetrical bridging imido ligands. Exchange between the bridging and the terminal imido ligands were observed on the NMR timescale, Delta G double dagger = 14.5+/-1.0 kcal mol(-1). An equilibration process is proposed to account for the fluxional behaviour.
SYNTHESES AND X-RAY CRYSTAL-STRUCTURES OF DICHLOROBIS(TERT-BUTYLIMIDO) COMPLEXES OF MOLYBDENUM(VI) - POTENTIAL PRECURSORS TO MOLYBDENUM NITRIDE AND MOLYBDENUM CARBONITRIDE
(1994-12-01)
CHIU, HT
;
CHANG, GB
;
HO, WY
;
CHUANG, SH
;
LEE, GH
The bistertbutylimido complexes [MoCl(mu L-Cl)(NBu(t))(2)(NH(2)Bu(t))](2), 1, and MoCl2(NBu(t))(2)(py)(2), 2 (py = pyridine), were prepared by reacting MoCl2(NBu(t))(2)(dme) (dme = dimethoxyethane) with excess Bu(t)NH(2) and pyridine, respectively. Their structures were determined by X-ray crystallography. 1 has a pseudo edge-shared bioctahedral geometry with two Cl ligands bridging the Mo centers unequally. Pertinent bond distances and angles for 1, Mo = NBu(bent)(t) = 1.737(3) Angstrom, angle Mo = N-CMe(3) = 154.0(2)degrees; Mo = NBu(linear)(t) = 1.725(3) Angstrom, angle Mo = N-CMe(3) = 172.4(2)degrees; Mo-Bu(t)NH(2) = 2.233(2) Angstrom; Mo=Cl-bridging = 2.575(1) and 2.835(1) Angstrom, and Mo-Cl-leminal = 2.428(1) Angstrom. Crystal data for 1: triclinic, space group P (1) over bar, a = 8.897(4) Angstrom, b = 10.518(3) Angstrom, c = 10.663(3) Angstrom, alpha = 107.68(2)degrees, beta = 98.03(3)Angstrom, gamma = 99.26(3)degrees, V = 919.3(5) Angstrom(3), Z = II D-c = 1.381 g/mL. 2 is mononuclear with a distorted octahedral geometry with two trans Cl ligands, two cis-oriented Bu(t)N = ligands, and two py ligands trans to the imido groups. Pertinent averaged bond distances and angles for 2, Mo = NBu(bent)(t) = 1.736(4) Angstrom, angle Mo = N-CMe, = 161.8(4)degrees; Mo = NBu(linear)(t) = 1.705(5) Angstrom, angle Mo = N-CMe(3) = 173.4(4)degrees; Mo-N(py)= 2.44(1), Mo-Cl = 2.421(3) Angstrom Crystal data for 2: orthorhombic, space group Pna2(1) a = 16.860(2) Angstrom, b = 8.920(3) Angstrom, c = 15.120(3) Angstrom, V = 2274.1(9) Angstrom(3), Z = 4, D-c = 1.362 g/mL. A potential application of 2 as a single-source precursor to grow molybdenum nitride and molybdenum carbonitride thin films by low pressure chemical vapor deposition (LPCVD) was explored. Cubic phase thin films (a(thin film) = 4.16 - 4.20 Angstrom) were grown at temperatures between 450 degrees C and 650 degrees C with hydrogen as carrier gas. At 450 degrees C, thin films of molybdenum nitride were obtained. With temperature of deposition increased from 450 degrees C to 650 degrees C, the ratio C/Mo increased from 0.03 to 0.5 whereas the ratio C/Mo decreased from 0.7 to 0.3. Thus, thin films of molybdenum carbonitride were deposited at 650 degrees C.
SYNTHESIS AND CHARACTERIZATION OF N=CR(OTBU)3
(1995-04-02)
CHIU, HT
;
CHEN, YP
;
LEE, GH
;
PENG, SM
;
應用化學系