Preparation and Tungsten-183 NMR Characterization of [α-1-P2W17O61]10-, [α-1-Zn(H2O)P2W17O61]8-, and [α-2-Zn(H2O)P2W17O61]8

• Published in: Inorganic chemistry 1996-03, Vol.35 (6), p.1497-1501
• Main Authors: Bartis, Judit, Kunina, Yuliya, Blumenstein, Michael, Francesconi, Lynn C
• Format: Article
• Language: English
• ISSN: 0020-1669; 1520-510X
• DOI: 10.1021/ic950492u

The preparation of the α-1 and α-2 isomers of the Wells−Dawson 17 tungsto derivatives by standard methods is accompanied by a significant proportion of the other isomer present as an impurity. In this study, the α-1 and α-2 isomers of [Zn(H2O)P2W17O61]8- have been prepared in >98% purity by reacting isomerically pure K9Li[α-1-P2W17O61] and K10[α-2-P2W17O61], respectively, with ZnCl2, while rigorously controlling the pH at 4.7. The molecules were isolated as potassium salts. For 183W NMR and 31P NMR characterization, both molecules were ion exchanged by cation-exchange chromatography, maintaining the pH at 4.7, to obtain the lithium salts. Removal of water and isolation of a solid sample of [α-1-Zn(H2O)P2W17O61]8- was achieved by lyophilization at −40 °C. The chemical shift data from 31P and 183W NMR spectroscopy of the isolated [α-1-Zn(H2O)P2W17O61]8- and [α-2-Zn(H2O)P2W17O61]8- isomers are consistent with a mixture of the α-1 and α-2 isomers reported previously; the molecules have the expected C 1 and C s symmetry, respectively. The [α-1-Zn(H2O)P2W17O61]8- isomer is stable in the pH range of 4.6−6 at temperatures