Polyoxometalate catalyst precursors. Improved synthesis, H{sup +}-titration procedure, and evidence for {sup 31}P NMR as a highly sensitive support-site indicator for the prototype polyoxoanion-organometallic-support system [(n-C{sub 4}H{sub 9}){sub 4}N]{sub 9}P{sub 2}W{sub 15}Nb{sub 3}O{sub 62}
- Colorado State Univ., Fort Collins, CO (United States)
An improved synthesis of the prototype polyoxoanion-organometallic-support system, P{sub 2}W{sub 15}Nb{sub 3}O{sub 62}{sup 9-}, as its organic solvent-soluble all-[(n-C{sub 4}H{sub 9}){sub 4}N]{sup +} salt is described. The improvements result in a 30% faster procedure which also provides a 60% increase in yield of [(n-C{sub 4}H{sub 9}){sub 4}N]{sub 9}P{sub 2}W{sub 15}Nb{sub 3}O{sub 62}, 2. One key improvement in this synthesis is a pH titration of protonated [(n-C{sub 4}H{sub 9}){sub 4}N]{sub 5}H{sub 4}P{sub 2}W{sub 15}Nb{sub 3}O{sub 62}, 1, using [(n-C{sub 4}H{sub 9}){sub 4}N]OH and phenolpthalein indicator, which leads to fully deprotonated 2-the key synthon required for clean support of organometallic cations onto the P{sub 2}W{sub 15}Nb{sub 3}O{sub 62}{sup 9-} polyoxoanion`s {open_quotes}Nb{sub 3}O{sub 9}{sup 3-}{close_quotes} cap. The material obtained from this procedure is of the highest purity ({ge}95%) seen to date as judged by {sup 31}P NMR spectroscopy. [(n-C{sub 4}H{sub 9}){sub 4}N]{sub 9}P{sub 2}W{sub 15}Nb{sub 3}O{sub 62} has been further characterized by {sup 1}H, {sup 13}C, {sup 17}O, and {sup 183}W NMR spectroscopy as well as IR spectroscopy and complete elemental analysis.
- DOE Contract Number:
- FG06-89ER13998
- OSTI ID:
- 513373
- Journal Information:
- Inorganic Chemistry, Vol. 35, Issue 26; Other Information: PBD: 18 Dec 1996
- Country of Publication:
- United States
- Language:
- English
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