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Doped Semimetal Clusters: Ternary, Intermetalloid Anions [Ln@Sn7Bi7]4– and [Ln@Sn4Bi9]4– (Ln = La, Ce) with Adjustable Magnetic Properties
- Lips, Felicitas, Hołyńska, Małgorzata, Clérac, Rodolphe, Linne, Uwe, Schellenberg, Inga, Pöttgen, Rainer, Weigend, Florian, Dehnen, Stefanie
- Journal of the American Chemical Society 2012 v.134 no.2 pp. 1181-1191
- anions, cations, magnetic properties, metalloids, oxidation, salts, topology
- Two K([2.2.2]crypt) salts of lanthanide-doped semimetal clusters were prepared, both of which contain at the same time two types of ternary intermetalloid anions, [Ln@Sn₇Bi₇]⁴– and [Ln@Sn₄Bi₉]⁴–, in 0.70:0.30 (Ln = La) or 0.39:0.61 (Ln = Ce) ratios. The cluster shells represent nondeltahedral, fullerane-type arrangements of 14 or 13 main group metal atoms that embed the Ln³⁺ cations. The assignment of formal +III oxidation states for the Ln sites was confirmed by means of magnetic measurements that reveal a diamagnetic La(III) compound and a paramagnetic Ce(III) analogue. Whereas the cluster anions with a 14-atomic main-group metal cage represent the second examples in addition to a related Eu(II) cluster published just recently, the 13-atomic cages exhibit a yet unprecedented enneahedral topology. In contrast to the larger cages, which accord to the Zintl–Klemm–Busmann electron number–structure correlation, the smaller clusters require a more profound interpretation of the bonding situation. Quantum chemical investigations served to shed light on these unusual complexes and showed significant narrowing of the HOMO–LUMO gap upon incorporation of Ce³⁺ within the semimetal cages.