COMPREHENSIVE STRUCTURAL AND SPECTROSCOPIC STUDY OF INTRAZEOLITE ANCHORING OF RUTHENIUM CARBONYL CLUSTERS

[Ru-3(CO)(12)] guests in Na56Y were thermally activated from 298 to 36 3 K, in a hydrogen atmosphere, generating intrazeolitic [H4Ru4(CO)(12) ]. Hexaammineruthenium(III) complexes in Na56X have been thermally act ivated progressively from 298 to 393 K, in CO and H-2 atmospheres. The generation process is via conversion of the intermediate [Ru(NK3)(5)( CO)](2+), Ru-1(CO)(3) to [Ru-6(CO)(18)](2-). The characterization of t he structure and properties of these samples used a multi-analytical a pproach based on FTIR, UV-VIS, EXAFS spectroscopies and CO and H-2 gas chemiscrption. The research encompassed several key points as follows : (i) kinetics of the intrazeolitic diffusion of [Ru-3(CO)(12)] cluste rs; (ii) oxidation fragmentation under O-2 atmosphere and reductive re generation under CO and H-2 chemisorption with temperature-programmed heating for the intrazeolite anchoring of [Ru-6(CO)(18)](2-); (iii) in ternal vs. external confinement of ruthenium carbonyl clusters; (iv) i ntrazeolite anchoring of ruthenium carbonyl clusters shows a strong re action with the extraframework Na+ alpha-cage cations, through involve ment of the oxygen end of the bridging or equatorial terminal carbonyl ligands; (v) comparison of orbitally degenerate ground-state for free Ru carbonyl clusters vs. the intrazeolitic anchoring site provides a theoretical indication of the symmetry distortion. These multi-analyti cal spectroscopic methods should motivate both new and established sci entists to study further the anchoring of metal carbonyl clusters with other types of zeolite (such as ZSM-5 or MCM-41). Faujasite mediated synthesis of metal carbonyl clusters can provide routes to compounds w hich are not accessible by conventional solution techniques. Further, higher yield clusters, as well as a better understanding of the nuclea tion process of cluster formation and of the resulting chemical proper ties can be expected.