Three series of hydroxyapatites (Hap) promoted by cobalt, have been synthesized using co-precipitation or impregnation methods, characterized by various techniques (XRD, UV-visible, Raman, and H 2 -TPR), and their catalytic properties were tested in the total oxidation of methanol. Characterization of the Co-promoted Hap solids showed that some Co 2? ions could incorporate the apatite structure and that bulk Co 3 O 4 entities could be formed outside the apatite grains. The activity for methanol oxidation of the cobalt-coprecipitated samples was low because structural cobalt ions are difficult to reduce, whereas the activity of the Co-impregnated samples was found to be very high since the methanol was totally converted at low temperature. This was related to the presence of Co 3 O 4 entities that are more easily reducible than structural Co ions and are found in higher quantity in the impregnated solids. This catalytic effect was highlighted using an Ca-deficient Hap as a support: cooperation of redox properties of Co 3 O 4 and acid properties of the apatite support led to a very efficient catalyst since the corresponding light-off temperature was lowered by 50°C with a catalyst containing 5 wt% of cobalt.

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A series of PNP−ruthenium(II) complexes Ru(OCOMe)2(PNP) (1), Ru(OCOMe)2(PNP)(PPh3) (2), the monohydrides RuHX(PNP)(PPh3) (X = OCOMe (3); X = Cl (4)), and dihydride RuH2(PNP)(PPh3) (5) (PNP = 2,6-bis(diphenylphosphinomethyl)pyridine) were synthesized and characterized by microanalysis as well as NMR, IR, and mass spectroscopies. The solution dynamics of complex 1 were studied by variable-temperature 1H and 31P{1H} NMR spectroscopies. The crystal structure of RuHCl(PNP)(PPh3) (4) was determined by X-ray crystallography, showing that the PNP ligand coordinates the Ru atom in a meridional mode. The hydrido complexes RuH(OCOMe)(PNP)(PPh3) (3) and RuH2(PNP)(PPh3) (5) undergo deuterium exchange reactions with CD3OD to give substitution of both the hydrides and PNP methylene protons by deuterium. The probable intermediates involved in these exchange processes are molecular dihydrogen complexes of Ru(II).

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