Gc. Shen et al., COMPREHENSIVE STRUCTURAL AND SPECTROSCOPIC STUDY OF INTRAZEOLITE ANCHORING OF RUTHENIUM CARBONYL CLUSTERS, Journal of the Chemical Society. Faraday transactions, 94(9), 1998, pp. 1353-1362
Citations number
49
Categorie Soggetti
Chemistry Physical","Physics, Atomic, Molecular & Chemical
[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.