13C and 23Na Solid-state NMR study on zeolite Y loaded with Mo(CO)6

H. Koller, A.R. Overweg, R.A. Santen, van, J.W. Haan, de

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Abstract

The Na-23 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 NH4+ Or H+, causes the sodium cations in the sodalite cages to migrate into the supercages in order to interact with the adsorbent. For the NH4+-exchanged sample, the anisotropic chemical shift parameters for C-13 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 degrees when it is located close to the sodium cations
Original languageEnglish
Pages (from-to)1754-1761
Number of pages8
JournalJournal of Physical Chemistry B
Volume101
Issue number10
DOIs
Publication statusPublished - 1997

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