13C and 23Na Solid-State NMR Study on Zeolite Y Loaded with Mo(CO)6

The 23 Na MAS and double rotation (DOR) NMR spectra of dehydrated zeolite NaY loaded with two molecules of Mo(CO) 6 per supercage show three components distinguished by the corresponding quadrupole coupling constants (QCC). Sodium cations in the hexagonal prisms (SI sites) are characterized by a narrow Gaussian line with a QCC value close to zero. A second component with quadrupole coupling constants between 4.4 and 4.8 MHz is assigned to Na + cations located in the sodalite cages, and the third component with QCC ranging between 2.2 and 2.8 MHz is due to sodium cations in the supercages interacting with Mo(CO) 6 . These sites are characterized by structural and/or dynamical disorder as observed by typical line shape properties. Adsorption of Mo(CO) 6 in Y zeolites, where all Na + cations in the supercages of NaY have been exchanged with NH 4 + or H +, causes the sodium cations in the sodalite cages to migrate into the supercages in order to interact with the adsorbent. For the NH 4 + -exchanged sample, the anisotropic chemical shift parameters for 13 C in Mo(CO) 6 have been analyzed at ambient temperature. From the results a fast anisotropic local reorientation of Mo(CO) 6 follows. The rotation is about a 3-fold axis of the octahedral complex. The octahedron is slightly elongated along the rotation axis by about 4° when it is located close to the sodium cations.