Spectroscopic characterisation of Grubbs 2nd generation catalyst and its p-cresol derivatives

Photocatalytic Decomposition of an Azo Dye Using Transition-Metal-Doped Tungsten and Molybdenum Carbides

The preparation, characterization, and photocatalytic application of tungsten or molybdenum carbides (Ni-WC, 1, Co-WC, 2, Ni-MoC, 3, Co-MoC, 4, NiCo-WC, 5, NiCo-MoC, 6, NiFe-WC, 7, and NiFe-MoC, 8) doped with transition metals (Fe, Co, and Ni) are reported. These transition-metal carbide (TMC) particles show that the submicrometer globular particles agglomerated to form larger particles, with smaller crystallites present on the surface of the large particles. These crystallite sizes range between 4 and 34 nm (as calculated from X-ray diffraction data) depending on the metal dopant and type of carbide. Oxidation of the metal carbides is evident from the two sets of photoelectron lines present in the X-ray photoelectron spectroscopy (XPS) of the W 4f area. The Mo 3d spectra reveal four sets of photoelectron lines associated with oxidized MoO₂ and MoO₃ as well as Mo²⁺ and Mo³⁺ associated with MoC_1-x . The XPS of the dopant metals Ni, Co, and Fe also show partial oxidation. The photocatalytic decomposition of Congo red (an azo dye) is used as a model reaction to determine the photocatalytic activities of the transition-metal carbides, which is related to the TMCs' optical band gap energies.

Comparison of the Spectroscopically Measured Catalyst Transformation and Electrochemical Properties of Grubbs' First- and Second-Generation Catalysts

According to UV-vis spectroscopy (0.10 mM, CH₂Cl₂ at 25 °C), the catalyst transformation (which could possibly include ligand dissociation with active catalyst formation, dimer formation, and decomposition) rate constants (k _obs) of Grubbs' first (1) and second (2) generation catalysts are 7.48 × 10^-5 and 1.52 × 10^-4 s^-1, respectively. From ³¹P NMR (0.1 M, CD₂Cl₂, at 25 °C), the catalyst transformation was 5.1% for 1 and 16.5% for 2 after 72 h. However, due to the larger concentrations of the NMR samples compared to the UV-vis samples, the extent of transformation did not correspond. The oxidation potential of the Ru^II/Ru^III couple of 2 (E°' = 27.5 mV at v = 200 mV s^-1) was considerably lower than that of 1 (E°' = 167 mV at v = 200 mV s^-1). In the case of 1, a second reduction peak appeared at slow scan rates. This may probably be ascribed to an electrochemically active compound that was formed from the intermediate cation 1 ^•+ and the subsequent reduction of the latter. The oxidation/reduction of 1 proceeds according to an E_rC_i electrochemical mechanism (E_r = electrochemically reversible step, C_i = chemically irreversible step), whereas 2 proceeds according to an E_rC_r electrochemical mechanism (E_r = electrochemically reversible step, C_i = chemically reversible step).

NMR data of a Grubbs 2nd generation catalyst p-cresolate derivative

The data presented in this article is related to the research article entitled “Spectroscopic characterisation of Grubbs 2^nd generation catalyst and its p-cresol derivatives” (Swart et al. 2021). The 1D and 2D NMR characterisation data of the p-cresol derivative of the Grubbs 2^nd generation catalyst, where one of the chloride ligands is replaced by the p-cresolate to form a Ru-O coordination compound (3) is reported. The characterization data include information obtained from ¹H, ¹³C, Heteronuclear Single Quantum Coherence (HSQC), Heteronuclear Multiple Bond Correlation (HMBC), Homonuclear Correlation Spectroscopy (COSY), Nuclear Overhauser Effect (NOE) and Distortionless Enhancement by Polarization Transfer (DEPT) NMR spectroscopy.