Utilisation of formed cyano-bridged coordination polymers as precursors of supported Ir-Ni alloy nanoparticles with precisely controlled compositions and sizes.

Ir-Ni alloys supported on SiO have been reported to show high catalytic activity for styrene hydrogenation; however, precise control of compositions and sizes of the Ir-Ni alloys is difficult when conventional metal salts are used as precursors. Furthermore, the concomitant formation of unalloyed Ni nanoparticles disturbs quantitative discussion about Ir-Ni alloy compositions. We report herein a preparation method of Ir-Ni alloys with precisely controlled compositions on SiO using Ni(NO) and an Ir complex possessing CN ligands, [Ir(CN)] or [Ir(ppy)(CN)] (ppy = 2-phenylpyridine), as precursors. The formation of cyano-bridged coordination polymers involving Ir and Ni promotes the formation of Ir-Ni alloys, whose compositions are virtually the same as expected from the amounts of Ir and Ni used for the preparation, after heat treatment under H. The use of [Ir(ppy)(CN)] as the precursor resulted in the formation of smaller Ir-Ni alloy particles than those with [Ir(CN)] related to the structures of the formed coordination polymers.