Topotactic Kinetics in Zeolite Nanoreaction Chambers
Year: 1992
Type: conference-paper
Abstract: The first kinetic study is reported for archetypical substitution reactions of PMe 3 and 13 CO with the well defined intrazeolite system Mo( 12 CO) 6- M 56 Y where M = Li, Na, K, Rb and Cs. Excellent isosbestic points and first-order dissociative behaviour are obtained, the activation parameters indicating a highly ordered supramolecular transition-state consisting of activated Mo( 12 CO) 6 and PMe 3 or 13 CO anchored to M + ions and/or oxygen-framework sites in the α-cage of the host lattice. Generally, an increase in reactant loading produces a decrease in the activating ability of the host lattice but, for reaction with PMe 3, reactivity is enhanced at higher loading and associative attack on Mo( 12 CO) 6 by PMe 3 may be important under some conditions. The global picture that emerges from this investigation is that the α-cages of zeolite Y behave as rigid macrospheroidal multidentate anionic ligands (called zeolates or cavitates) towards extraframework charge-balancing cations to which organometallic and ligand guests can become attached. An approach of this kind can assist with the design of experiments and the understanding of cation and framework anchoring and guest loading effects on the activation parameters and reaction mechanisms compared to gas, solution, surface, and matrix phases where such data are available.
Source: ACS symposium series
Language: English
Subfield: Inorganic Chemistry
Field: Chemistry
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W2495373301