Surface-Chemistry of Rh-Carbonyls and Nitrosyls on Dealuminated Y-Zeolite at Low-Temperature

FTIR spectroscopy at low temperature (77–300 K) has been used to study the surface species formed during the interaction of CO and NO with RhI(CO)2 and RhI(NO)2 on highly dealuminated zeolite Y (US-Ex). A series of different well defined surface carbonyls and nitrosyls including mixed NO–CO compounds was obtained in addition to the dicarbonyl and dinitrosyl. With CO a Rh tricarbonyl with C3v symmetry and a tetracarbonyl with C2v symmetry are suggested and identified by ligand exchange with 12C18O and 13C16O and a calculation of the force constants within the framework of an energy-separated force field. As an intermediate in the ligand exchange reaction between RhI(CO)2 and RhI(NO)2 the mixed surface compound RhI(CO)(NO)2 could be identified.