Treatment of C5H6M(CO)4 (M = Nb, Ta) with sodium in liquid ammonia at-78 °C generates the corresponding disodium salts Na2[C6H6M(CO)3], which have been spectroscopically identified. Cesium iodide reacts with Na2[C5H6M(CO)3] in liquid ammonia to provide 70-80% isolated yields of pale orange, air-sensitive solids that analyze satisfactorily as the unsolvated dicesium salts Cs2[C6H6M(CO)3]. These are the first isolated salts containing the tricarbonylcyclopentadienylmetalate dianions of niobium and tantalum. Reactions of C5H5M(CO)32- with CH3CN, Et4N+, or other weak Bronsted acids or Ph3SnCl provide, after cation exchange, 40-70% isolated yields of [Et4N] [C6H6M(CO)3H] or [Et4N][C5H5M(CO)3SnPh3], which are characterized by elemental analyses and 1H and NMR spectra.
|Original language||English (US)|
|Number of pages||4|
|State||Published - Jan 1984|