Mononuclear iridium dinitrogen complexes bonded to zeolite HY.
The adsorption of N2 on structurally well-defined dealuminated HY zeolite-supported iridium diethylene complexes was investigated. Iridium dinitrogen complexes formed when the sample was exposed to N2 in H2 at 298 K, as shown by infrared spectra recorded with isotopically labeled N2 . Four supported species formed in various flowing gases: Ir(N2 ), Ir(N2 )(N2 ), Ir(C2 H5 )(N2 ), and Ir(H)(N2 ). Their interconversions are summarized in a reaction network, showing, for example, that, in the presence of N2 , Ir(N2 ) was the predominant dinitrogen species at temperatures of 273-373 K. Ir(CO)(N2 ) formed transiently in flowing CO, and in the presence of H2 , rather stable iridium hydride complexes formed. Four structural models of each iridium complex bonded at the acidic sites of the zeolite were employed in a computational investigation, showing that the calculated vibrational frequencies agree well with experiment when full calculations are done at the level of density functional theory, independent of the size of the model of the zeolite.
Department of Chemical Engineering & Materials Science, University of California, Davis, One Shields Ave, Davis, CA 95616 (USA).
Dong
D
Yang
Mingyang
M
Chen
Claudia
C
Martinez-Macias
David A
DA
Dixon
Bruce C
BC
Gates
density functional calculations; dinitrogen adsorption; iridium; supported complexes; zeolites