First‐row transition‐metal complexes hold great potential as catalysts for hydrogenations and related reductive reactions. Homo‐ and heteroleptic arene/alkene metalates(1−) (M=Co, Fe) are a structurally distinct catalyst class with good activities in hydrogenations of alkenes and alkynes. The first syntheses of the heteroleptic cobaltates [K([18]crown‐6)][Co(η4‐cod)(η2‐styrene)2] (5) and [K([18]crown‐6)][Co(η4‐dct)(η4‐cod)] (6), and the homoleptic complex [K(thf)2][Co(η4‐dct)2] (7; dct=dibenzo[a,e]cyclooctatetraene, cod=1,5‐cyclooctadiene), are reported. For comparison, two cyclopentadienylferrates(1−) were synthesized according to literature procedures. The isolated and fully characterized monoanionic complexes were competent precatalysts in alkene hydrogenations under mild conditions (2 bar H2, r.t., THF). Mechanistic studies by NMR spectroscopy, ESI mass spectrometry, and poisoning experiments documented the operation of a homogeneous mechanism, which was initiated by facile redox‐neutral π‐ligand exchange with the substrates followed by H2 activation. The substrate scope of the investigated precatalysts was also extended to polar substrates (ketones and imines).

We report on the asymmetric occupation of a 12‐vertex cluster centered by a single metal atom. Three salts of related intermetalloid cluster anions, [Co@Sn6Sb6]3− (1), [Co2@Sn5Sb7]3− (2), and [Ni2@Sn7Sb5]3− (3) were synthesized, which have pseudo‐C4v‐symmetric or pseudo‐D4h‐symmetric 12‐vertex Sn/Sb shells and interstitial Co− ions or Ni atoms. Anion 1 is a very unusual single‐metal‐“centered” 12‐atom cluster, with the inner atom being clearly offset from the cluster center for energetic reasons. Quantum chemistry served to assign atom types to the atomic positions and relative stabilities of this cluster type. The studies indicate that the structures are strictly controlled by the total valence electron count—which is particularly variable in ternary intermetalloid cluster anions. Preliminary 119Sn NMR studies in solution, supported by quantum‐chemical calculations of the shifts, illustrate the complexity regarding Sn:Sb distributions of such ternary systems.

Small Co(0) nanoparticles catalyze hydrogenations of alkenes, alkynes, imines, and heteroarenes; the magnetic properties enabled catalyst separation and multiple recyclings.

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Wir berichten von dem asymmetrischen Einschluss eines einzelnen Metallatoms in einen 12‐atomigen Cluster. Drei Salze verwandter intermetalloider Clusteranionen, [Co@Sn6Sb6]3− (1), [Co2@Sn5Sb7]3− (2) und [Ni2@Sn7Sb5]3− (3) wurden synthetisiert, die pseudo‐C4v‐ oder pseudo‐D4h‐symmetrische 12‐atomige Sn/Sb‐Clusterhüllen und interstitielle Co−‐Ionen oder Ni‐Atome besitzen. 1 ist ein sehr ungewöhnlicher, durch ein einzelnes Metallatom “zentrierter” 12‐Atom‐Cluster, da das innere Atom aus energetischen Gründen klar aus einer zentralen Position ausgelenkt ist. Mittels quantenchemischer Rechnungen konnten die Atomsorten den Atompositionen zugeordnet und relative Stabilitäten möglicher Isomere dieses Clustertyps bestimmt werden. Die Studien zeigen, dass die Gesamtvalenzelektronenzahl der Cluster – die bei ternären intermetalloiden Clusteranionen besonders leicht variiert – ihre Struktur determiniert. Erste 119Sn‐NMR‐Studien in Lösung, die von quantenchemischen Rechnungen flankiert wurden, illustrieren die Komplexität solcher Systeme bezüglich der Sn:Sb‐Verteilung.