Guest-host interactions in sodium zeolite Y: structural and dynamical 23Na double-rotation NMR study of water, trimethylphosphine, molybdenum hexacarbonyl, and Mo(CO)4(PMe3)2 adsorption in Na56Y Academic Article uri icon

abstract

  • 23Na double-rotation NMR (DOR) provides site-specific structural and dynamical information on guest-host interactions within sodium zeolite Y pores. Quantitative adsorption of H2O, PMe3, and Mo(CO)6 guests affects both the positions and line shapes of the 23Na resonances from specific extraframework Na+ sites. The evolution of the 23Na DOR spectra with the progressive introduction of guest molecules allows one to probe direct "solvation" effects involving the Na+ cations in the larger supercages, as well as indirect effects on the Na+ cations in adjacent smaller sodalite cavities. 23Na DOR experiments conducted at two magnetic field strengths confirm that PMe3 coadsorption in 8{Mo(CO)6),16{PMe3)-Na56Y, and PMe3 ligand-substitution in 8{cis-Mo(CO)4(PMe3)2]-Na56Y give rise to progressive deshielding and enhanced quadrupolar interactions of the anchoring Na+ cations in the α-cages, relative to those of the starting material, 8{Mo(CO)6}-Na56Y. Spin-lattice relaxation measurements indicate that adsorption of PMe3 facilitates an increased motion of the Na+ cations and/or guest species inside the α-cages.

publication date

  • May 1, 2002