ELECTRON-STRUCTURE OF HIGHLY SYMMETRICAL COMPOUNDS OF F-ELEMENTS .23. HOW LARGE ARE THE CRYSTAL-FIELD SPLITTING EFFECTS IN TRIS(BIS(TRIMETHYLSILYL)AMIDO) COMPLEXES OF LANTHANOIDS

The sigma and pi-absorption spectrum of the H-3(4) --> P-3(0) transition has been measured at room temperature on an oriented single crystal of tris(bis(trimethylsilyl)amido)praseodymium (III) as well as the room temperature magnetic circular dichroism spectrum of the compound dissolved in a mixture of toluene and methylcyclohexane in the ratio 1:1. From these data the crystal field (CF) splitting of the ground H-3(4) manifold was derived. An approximate set of CF parameters was obtained which qualitatively reproduces the experimental levels. The magnitude of the CF parameters demonstrates that the three bis(trimethylsilyl)amido ligands produce an unusually large crystal field.