Reactivity of U3+ Metallocene Allyl Complexes Leads to a Nanometer-Sized Uranium Carbonate, [(C5Me5)2U]6(μ‑κ1:κ2‑CO3)6
journal contributionposted on 09.09.2013, 00:00 by Christopher L. Webster, Joseph W. Ziller, William J. Evans
The U3+ allyl complexes (C5Me5)2U[CH2C(R)CH2] (R = H, Me) display three different types of reactivity, as exemplified by reactions with PhNNPh, cyclooctatetraene, and CO2. Two equivalents of (C5Me5)2U[CH2C(R)CH2] effect a four-electron reduction of PhNNPh 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.