Safe, One-Pot, Homogeneous Direct Synthesis of H2O2

Hydrogen peroxide is an environmentally friendly oxidizing agent but current synthetic methods are wasteful. This is a result of the high flammability of H₂/O₂ mixtures and/or the requirement for cocatalysts. In this paper, we report the synthesis of H₂O₂ by means of a homogeneous catalyst, which allows a safe, one-pot synthesis in water, using only H₂ and O₂. This catalyst is capable of removing electrons from H₂, storing them for the reduction of O₂, and then permitting the protonation of the reduced oxygen to H₂O₂. The turnover number (TON) is 910 under an H₂/O₂ (95/5) atmosphere (1.9 MPa) for 12 h at 23 °C, which is the highest of any homogeneous catalyst. Furthermore, we propose a reaction mechanism based on two crystal structures.

Synthesis of acetic acid from CO2, CH3I and H2 using a water-soluble electron storage catalyst

This paper reports a possible mechanism of acetic acid formation from CO2, CH3I and H2 in aqueous media and the central role played by a water-soluble Rh-based electron storage catalyst. In addition to water-solubility, we also report the crystal structures of two presumed intermediates. These findings together reveal (1) the advantage of water, not only as a green solvent, but also as a reactive Lewis base to extract H+ from H2, (2) the role of the metal (Rh) centre as a point for storing electrons from H2 and (3) the importance of an electron-withdrawing ligand (quaterpyridine, qpy) that supports electron storage.

A supramolecular recyclable catalyst for aqueous Suzuki–Miyaura coupling

A Pd(ii) pyrazolyl complex is solubilized by host–guest inclusion to give an efficient, recyclable catalyst for Suzuki–Miyaura couplings in aqueous–organic solvents.

[N.1.1]-(2,6)-Pyridinophanes: a new ligand type imposing unusual metal coordination geometries

A series of new ligands with three pyridines linked into a macrocycle by various CH(2), CMe(2), and CH(2)CH(2) groups at all sites ortho to the pyridine nitrogen have been synthesized and attached to PdCl(2) or PtMe(2). The ligands bind to them through only two nitrogens, and the third pyridine is constrained in close proximity to the planar complex with a filled d(z)2 orbital. Rapid reversible migration of PdCl(2) or PtMe(2) to the unused pyridine nitrogen is observed at 20 degrees C in the case of the CH(2)-bridged macrocycle and does not occur in the case of the CMe(2)-bridged analogue, and the mechanism of this fluxionality has been established by NMR and computational techniques.