A Heterobimetallic Complex With an Unsupported Uranium(III)−Aluminum(I) Bond: (CpSiMe₃)₃U−AlCp* (Cp* = C₅Me₅)

Abstract

The discovery of molecular metal-metal bonds has been of fundamental importance to the understanding of chemical bonding.1 For the actinides, examples of unsupported metalmetal bonds are relatively uncommon, consisting of Cp 3 USnPh 3 , and several actinide-transition metal complexes. Traditionally, bonding in the f-elements has been described as electrostatic; however, elucidating the degree of covalency is a subject of recent research. 3 In carbon monoxide complexes of the trivalent uranium metallocenes, decreased ν CO values relative to free CO suggest that the U(III) atom acts as a π-donor. 4 Ephritikhine and coworkers have demonstrated that π-accepting ligands can differentiate trivalent lanthanide and actinide ions, an effect that renders this chemistry of interest in the context of nuclear waste separation technology.

Non-traditional ligands in f-block chemistry

“…It was therefore proposed that the lower magnetic moment of 59 was due to the cationic nature of 59 resulting in a shorter uranium-iron distance and better orbital overlap. (60), which was isolated as dark brown crystals from cold (K808C) pentane (Minasian et al 2008). An X-ray diffraction study revealed an unsupported uranium-aluminium bond with a uranium-aluminium bond distance of 3.117(3) Å, which is within the sum of the covalent radii of uranium and aluminium (3.17 Å) (Cordero et al 2008).…”

Substituent‐Free Gallium by Hydrogenolysis of Coordinated GaCp*: Synthesis and Structure of Highly Fluxional [Ru2(Ga)(GaCp*)7(H)3]

“…[2] Much work has been done elucidating the bonding properties of similar d/f-block compounds of the general formula…”

“…These data are quite comparable to the Ru À Ga distances in related RuÀGaCp* complexes and clusters. [14,15] Following usual electron-counting rules, 1 can be viewed as being formally composed of the unsaturated neutral 16 electron fragment {(GaCp*) 3 (H) 2 Ru II } and the saturated neutral 18 electron fragment {(GaCp*) 4 . [9] Note, that the Pt dimer [Pt 2 H(Ga)-(GaCp*) 7 ] 2+ is isoelectronic to 1 (a total of 34 valence electrons for both M 2 Ga 8 core structures).…”

Ein substituentenfreier Galliumligand durch Hydrogenolyse von koordiniertem GaCp*: Synthese und Struktur des hoch fluktionalen [Ru2(Ga)(GaCp*)7(H)3]

“…[1] Ein jüngeres Glanzlicht ist der Komplex [h 5 -{(Me 3 Si)C 5 H 4 } 3 U(AlCp*)] mit der ersten freien ActinoidAluminium-Bindung. [2] Viel Arbeit wurde in die Untersuchung der Bindungseigenschaften von ähnlichen d-f-BlockVerbindungen der allgemeinen Formel [L a M b (ER) c ] investiert, [3] während über ihre metallorganischen Reaktionen und die damit verbundenen Anwendungsmöglichkeiten deutlich weniger berichtet wurde. Die homoleptischen Verbindungen [M a (ECp*) b ] sind wegen der flexiblen Bindungseigenschaften der Cp*-Gruppen am Gruppe-13-Metallatom von besonderem Interesse.…”

“…Diese Daten entsprechen den Ru-Ga-Abständen verwandter Ru-GaCp*-Komplexe und -Cluster. [14,15] Unter Verwendung üblicher Elektronenzählregeln (mit dem 2e-Donorligand H À und dem "nackten" Ga-Ligand als 0e-Donor Ga + ) setzt sich 1 formell zusammen aus einem ungesättigten neutralen 16e-Fragment {(GaCp*) 3 (H) 2 Ru II } und einem gesättigten 18e-Fragment {(GaCp*) 4 (H)Ru 0 (Ga)}. Die lineare Ru-Ga-Ru-Anordnung von 1 begründet sich durch die starken s-und p-Akzeptoreigenschaften von "nacktem" Ga…”