title: Formation of nonclassical carbonyls of Au3+ in zeolite NaY: characterization by infrared spectroscopy.
abstract: Adsorption of CO on gold supported in zeolite NaY at 85 K led to the formation of (i) various carbonyls and isocarbonyls typical of the zeolite and (ii) carbonyls formed at cationic gold sites (observed in the 2186-2171 cm(-1) region). Analysis of the behavior of the bands allows their assignment to carbonyls of Au(3+) ions. At temperatures higher than 220 K, CO adsorption led to the formation of a new type of Au(3+)-CO species (2207 cm(-1)). Once formed, these complexes could be transformed into the dicarbonyls Au(3+)(CO)(2) when the sample was cooled to 85 K in the presence of CO. The results are explained by migration of Au(3+) ions to more accessible positions within the zeolite at increasing temperatures. When a CO molecule is already adsorbed, it stabilizes the Au(3+) ion in the new position, and a second CO molecule can be coordinated, thus forming a geminal species. These results are the first evidence of Au(3+)(CO)(2) complexes.
authors.affiliation: Institute of General and Inorganic Chemistry, Bulgarian Academy of Sciences, Sofia 1113, Bulgaria.
authors.forename: Mihail Y
authors.initials: MY
authors.lastname: Mihaylov
authors.forename: Juan C
authors.initials: JC
authors.lastname: Fierro-Gonzalez
authors.forename: Helmut
authors.initials: H
authors.lastname: Knözinger
authors.forename: Bruce C
authors.initials: BC
authors.lastname: Gates
authors.forename: Konstantin I
authors.initials: KI
authors.lastname: Hadjiivanov