No abstract

[reaction: see text]. A new concept for recycling asymmetric bis(oxazoline)-type catalysts is reported. The formation of charge-transfer complexes between the chiral ligand and trinitrofluorenone and their subsequent precipitation and reuse by addition of new substrate solutions is described. The efficiency of this procedure is demonstrated in a Diels-Alder reaction to reach the expected endo product as major isomer (up to 97% de and 94% ee): the catalyst was used up to 12 times without loss of either activity or selectivity.

Electrocatalysts based on molybdenum, ruthenium, and selenium were prepared by screen printing Ru3 (CO)12 + Se and Ru3 (CO)12 + Mo(CO)6 + Se mixtures and subsequent sintering at 250°C in air or Se atmosphere in a tubular furnace. The catalysts were characterised using techniques such as XRD, SEM, TEM, voltammetry, and polarisation (current–potential) measurements. The results indicate that screen printed Rux Sey (CO)n and Mox Ruy Sez (CO)n are near amorphous in nature and possess appreciable catalytic activity for the oxygen reduction reaction in a polymer electrolyte (Nafion membrane) fuel cell. The electrocatalytic activity seems to diminish with selenium incorporation in the lattice of the carbonyl clusters formed during synthesis.