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The oxygen electro-reduction properties of various platinum alloys were studied using a combinatorial high throughput method. Binary and ternary platinum alloys were fabricated using a multi-source physical vapor deposition system and the resulting thin film samples were electrochemically screened by the hydrodynamic rotating disk electrode technique. By comparing the activity-stability-composition relationship between these alloys and a pure platinum film, over 10 alloy catalyst candidates were identified with mass-fraction specific activities of 5 to 10 times that of pure platinum. Additionally, organometallic synthesis methods have been studied to synthesize carbon supported alloy nanoparticles. A good relationship of the molecular oxygen electro-reduction has been found between alloy thin film and powder catalysts.

A 5% w/w palladium loading on silica has been achieved via impregnation of the support with Pd(C2H3O2)2and { (DMF)10Yb2[Pd(CN)4]3} ∞precursors to deliver monometallic (Pd/SiO2) and bimetallic (Yb–Pd/SiO2) catalyst systems respectively. The catalytic action of each has been assessed in the continuous gas‐phase hydrodechlorination (HDC) of chlorobenzene (CB) and 1,2‐dichlorobenzene (1,2‐DCB) (T= 423 K, inlet chlorine/palladium mol ratio of 5 × 103h−1) and the hydrogenation of benzene (T= 423 K, inlet C6H6/palladium mol ratio of 35 h−1). Activation of both catalysts delivered similar palladium crystallite size distributions with an average palladium diameter of 5–6 nm where the ytterbium component (in Yb–Pd/SiO2) was present as a thin surface coating. The Pd–Yb bimetallic exhibited significantly higher HDC and hydrogenation activities, the former manifested by significantly greater fractional dechlorinations and benzene selectivities/yields. Yb/SiO2proved inactive in terms of promoting hydrogen scission or addition and the promotional effect of ytterbium in Yb–Pd/SiO2is discussed in terms of electron donation and hydrogen transfer via surface YbH2. Under identical reaction conditions, a lower HDC activity was recorded for 1,2‐DCB compared with CB, a response that is attributed to steric constraints allied to the deactivating effect of the second chlorine substituent. Both Pd/SiO2and Yb–Pd/SiO2exhibited a decline in HDC activity with time‐on‐stream, but the bimetallic was significantly more resistant to deactivation. Copyright © 2003 John Wiley & Sons, Ltd.

A 5% w/w palladium loading on silica has been achieved via impregnation of the support with Pd(C2H3O2)2 and { (DMF)10Yb2[Pd(CN)4]3} ∞ precursors to deliver monometallic (Pd/SiO2) and bimetallic (Yb–Pd/SiO2) catalyst systems respectively. The catalytic action of each has been assessed in the continuous gas-phase hydrodechlorination (HDC) of chlorobenzene (CB) and 1,2-dichlorobenzene (1,2-DCB) (T = 423 K, inlet chlorine/palladium mol ratio of 5 × 10³ h⁻¹) and the hydrogenation of benzene (T = 423 K, inlet C6H6/palladium mol ratio of 35 h⁻¹). Activation of both catalysts delivered similar palladium crystallite size distributions with an average palladium diameter of 5–6 nm where the ytterbium component (in Yb–Pd/SiO2) was present as a thin surface coating. The Pd–Yb bimetallic exhibited significantly higher HDC and hydrogenation activities, the former manifested by significantly greater fractional dechlorinations and benzene selectivities/yields. Yb/SiO2 proved inactive in terms of promoting hydrogen scission or addition and the promotional effect of ytterbium in Yb–Pd/SiO2 is discussed in terms of electron donation and hydrogen transfer via surface YbH2. Under identical reaction conditions, a lower HDC activity was recorded for 1,2-DCB compared with CB, a response that is attributed to steric constraints allied to the deactivating effect of the second chlorine substituent. Both Pd/SiO2 and Yb–Pd/SiO2 exhibited a decline in HDC activity with time-on-stream, but the bimetallic was significantly more resistant to deactivation. Copyright © 2003 John Wiley & Sons, Ltd.

Catalysts CH3COCo(CO)3PPh3 (1) and HCo(CO)3PPh3 (2) catalyze the copolymerization of aziridine and carbon monoxide. Catalyst 2 can be conveniently generated in situ via reaction of Na⁺Co(CO)4, N,N-dimethylanilinium chloride, and PPh3. The copolymerization alternates at high catalyst loadings to produce poly(β-alanine). The end groups of the poly(β-alanine) product are characterized by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and by comparison of the ¹H NMR spectra of the polymer and a stepwise synthesized model compound. At low catalyst loadings, the polymer product contains both the β-alanine units and amine units because of nonalternating enchainment of the comonomers. The characterization of the amine units is again supported by comparison of the ¹H NMR spectra of the polymers and the stepwise synthesized model compounds. The molecular weights of the polymers are determined by gel permeation chromatography. The thermal stability of the polymers is probed by differential scanning calorimetry and thermogravimetric analysis. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 376–385, 2003

Aminolysis of Zr(CH₂C₆H₅)₄ with CH[(CH₃)₂SiNHAr]₃ (Ar = para-tolyl and para-fluorophenyl) affords CH[(CH₃)₂SiNAr]₃ZrCH₂C₆H₅ 1a and 1b (a: Ar = para-tolyl; b: Ar = para-fluorophenyl). Solution and solid state X-ray structural data suggest an η2-bonding mode for the benzyl group in 1a and 1b. Treating 1a and 1b with N,N-dimethylanilinium chloride or triphenylmethyl chloride yields CH[(CH₃)₂SiNAr]₃ZrCl (2a and 2b). Complex 2a exhibits a fast dimer–monomer equilibrium in benzene. Single-crystal X-ray diffraction of 2a reveals a dimeric structure bridged by two μ-Cl atoms. Metathesis of 2a and 2b with n-butyllithium in toluene and then in hexane yields CH[(CH₃)₂SiNAr]₃ZrnBu (3a and 3b). The crystal structures and the IR spectra of 3a and 3b in Nujol mulls reveal weak β-agostic interactions, but solution NMR spectra of 3a and 3b give no evidence for such a motif. Further, the larger Zr–Cα–Cβ angles and the longer Zr–Cβ distances suggest the β-agostic interactions in 3a and 3b are weaker than those in the previously reported cases of Group 4 metals. Complexes 1a, 1b, 3a, and 3b are active alkene hydrosilation catalysts. The catalytic activities exhibited by these complexes are in contrast to the inertness of the previously reported neutral molecules of the type X₃MR (X = amide, alkoxide, or siloxide; M = Group 4 metal; R = alkyl or hydride). We attribute the improved activity to three factors: the small ancillary groups of the ligand, the accessibility of the coordination sites cis to the Zr-alkyl group due to the small “bite angle” of the ligand, and the weakened N(p) → Zr(d) π donation due to the coordination geometry imposed by the tripodal ligand.

Alternating copolymerization of carbon monoxide with aziridine was realized, which serves as a prototype of a novel route for synthesis of poly-β-peptides.

The oxygen electro-reduction properties of various platinum alloys were studied using a combinatorial high throughput method. Binary and ternary platinum alloys were fabricated using a multi-source physical vapor deposition system and the resulting thin film samples were electrochemically screened by the hydrodynamic rotating disk electrode technique. By comparing the activity-stability-composition relationship between these alloys and a pure platinum film, over 10 alloy catalyst candidates were identified with mass-fraction specific activities of 5 to 10 times that of pure platinum. Additionally, organometallic synthesis methods have been studied to synthesize carbon supported alloy nanoparticles. A good relationship of the molecular oxygen electro-reduction has been found between alloy thin film and powder catalysts.

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