Between Localization and Delocalization: Ru(cod) Units in the Zintl Clusters [Bi {Ru(cod)} ] and [Tl Bi {Ru(cod)}].

Reactions of [K(crypt-222)] (TlBi )⋅0.5 en (1 b) with [Ru(cod)(H CC(Me)CH ) ] (A) in 1,2-diaminoethane (en) led to the formation of two compounds with new bismuth-rich cluster anions, [K(crypt-222)] [Bi {Ru(cod)} ]⋅1.5 en (2) and [K(crypt-222)] [Tl Bi {Ru(cod)}]⋅2 tol (3), alongside the salt of a binary nido cluster, [K(crypt-222)] (Tl Bi )⋅2 en (4). The anions in 2 and 3 are two further examples of rare heterometallic clusters containing Ru atoms. As one cod ligand is retained on each Ru atom in both clusters, the anions may be viewed as intermediates on the way towards larger, ligand-free intermetalloid clusters. Quantum-chemical studies provided insight into the bonding situation in these clusters. According to these studies, the anion of 2 features both electron-precise and electron-deficient parts. Electrospray ionization mass spectrometry analysis indicated that the clusters undergo stepwise fragmentation.