Transition metal germylene complexes in zeolite cages: Anchoring and stability
- Purdue Univ., West Lafayette, IN (United States)
The surface chemistry of the two germylene complexes Cl{sub 2}(THF)GeM(CO){sub 5} (M = Mo (1) and W (2)) in zeolite Y was studied with X-ray absorption spectroscopy (Ge, Mo, W edge EXAFS) and in situ FTIR/TPD-MS techniques. The molybdenum complex 1 interacts with the framework of Na-Y zeolite at room temperature where decarbonylation occurs to a small extent. The intrazeolite 1 retains the Ge-Mo bond is retained up to about the same temperature. At higher temperatures, the Ge-Mo bond is cleaved and MoCl{sub d} and Mo-Mo species are formed in the Na-Y and H-Y forms, respectively. GeCl{sub x} fragments attach to both zeolite frameworks. The intrazeolite complex Cl{sub 2}(THF)GeW(CO){sub 5} (2) retains all five carbonyl ligands up to about 100 {degrees}C in both Na-Y and at about 80 {degrees}C in the proton form. The intrazeolite stability of the anchored Ge-W complex is somewhat higher than that of the Ge-Mo analog, and WCl{sub x} species are formed upon cleavage of the Ge-W bond at higher temperatures. The anchoring of the Cl{sub 2}(THF)Ge moiety into Na-Y is believed to be based upon a Na{sup +}--Cl{sup -} interaction between Na ions in zeolite coordination sites and the chloride ligands of the precursor. The only gas evolution detected up to about 120 {degrees}C is due to partial decarbonylation (CO) and HCl formation in the acid supports. The absence of precursor desorption confirms the effective anchoring of the transition-metal germylene complexes into zeolite cages. 39 refs., 16 figs., 6 tabs.
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- FG04-90ER14158; AS05-80ER10742
- OSTI ID:
- 468082
- Journal Information:
- Journal of Physical Chemistry, Vol. 96, Issue 16; Other Information: PBD: 6 Aug 1992
- Country of Publication:
- United States
- Language:
- English
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