Mihaylov Mihail Y, Fierro-Gonzalez Juan C, Knözinger Helmut, Gates Bruce C, Hadjiivanov Konstantin I
Institute of General and Inorganic Chemistry, Bulgarian Academy of Sciences, Sofia 1113, Bulgaria.
J Phys Chem B. 2006 Apr 20;110(15):7695-701. doi: 10.1021/jp057426q.
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.
85K下，CO在负载于沸石NaY上的金表面的吸附导致了以下物质的形成：（i）沸石特有的各种羰基化合物和异羰基化合物；（ii）在阳离子金位点形成的羰基化合物（在2186 - 2171cm⁻¹区域观察到）。对这些谱带行为的分析使得它们能够被归属为Au(3+)离子的羰基化合物。在高于220K的温度下，CO吸附导致形成一种新型的Au(3+)-CO物种（2207cm⁻¹）。一旦形成，当样品在CO存在下冷却至85K时，这些配合物可以转化为二羰基化合物Au(3+)(CO)₂。结果表明，随着温度升高，Au(3+)离子会迁移至沸石内更易到达的位置。当一个CO分子已经被吸附时，它会在新位置稳定Au(3+)离子，并且第二个CO分子可以配位，从而形成偕二羰基物种。这些结果是Au(3+)(CO)₂配合物的首个证据。
