Reactivity of U3+ Metallocene Allyl Complexes Leads to a Nanometer-Sized Uranium Carbonate, [(C5Me5)2U]6(μ‑κ1:κ2‑CO3)6

The U3+ allyl complexes (C5Me5)2U­[CH2C­(R)­CH2] (R = H, Me) display three different types of reactivity, as exemplified by reactions with PhNNPh, cyclooctatetraene, and CO2. Two equivalents of (C5Me5)2U­[CH2C­(R)­CH2] effect a four-electron reduction of PhNNPh to form the bis­(imido) complex (C5Me5)2U­(NPh)2 and the bis­(allyl) species (C5Me5)2U­[CH2C­(R)­CH2]2. Two-electron reduction of C8H8 occurs to form (C5Me5)­(C8H8)­U­[CH2C­(R)­CH2] products that contain only one cyclopentadienyl ring per metal. With CO2 at 80 psi, both reduction and insertion occur. A hexametallic uranium carbonate, [(C5Me5)2U]6(μ-κ1:κ2-CO3)6, is isolated as well as the bis­(carboxylate) complexes (C5Me5)2U­[κ2-O,O′-O2CCH2C­(R)CH2]2. The polymetallic carbonate complex can also be synthesized from [(C5Me5)2U]2(μ-η6:η6-C6H6) and [(C5Me5)2U]­[(μ-Ph)2BPh2] and CO2.