Reactivity of U<sup>3+</sup> Metallocene Allyl Complexes
Leads to a Nanometer-Sized
Uranium Carbonate, [(C<sub>5</sub>Me<sub>5</sub>)<sub>2</sub>U]<sub>6</sub>(μ‑κ<sup>1</sup>:κ<sup>2</sup>‑CO<sub>3</sub>)<sub>6</sub>
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Abstract
The U<sup>3+</sup> allyl complexes
(C<sub>5</sub>Me<sub>5</sub>)<sub>2</sub>U[CH<sub>2</sub>C(R)CH<sub>2</sub>] (R = H, Me) display
three different types of reactivity, as exemplified by reactions with
PhNNPh, cyclooctatetraene, and CO<sub>2</sub>. Two equivalents
of (C<sub>5</sub>Me<sub>5</sub>)<sub>2</sub>U[CH<sub>2</sub>C(R)CH<sub>2</sub>] effect a four-electron reduction of PhNNPh to form
the bis(imido) complex (C<sub>5</sub>Me<sub>5</sub>)<sub>2</sub>U(NPh)<sub>2</sub> and the bis(allyl) species (C<sub>5</sub>Me<sub>5</sub>)<sub>2</sub>U[CH<sub>2</sub>C(R)CH<sub>2</sub>]<sub>2</sub>. Two-electron
reduction of C<sub>8</sub>H<sub>8</sub> occurs to form (C<sub>5</sub>Me<sub>5</sub>)(C<sub>8</sub>H<sub>8</sub>)U[CH<sub>2</sub>C(R)CH<sub>2</sub>] products that contain only one cyclopentadienyl ring per
metal. With CO<sub>2</sub> at 80 psi, both reduction and insertion
occur. A hexametallic uranium carbonate, [(C<sub>5</sub>Me<sub>5</sub>)<sub>2</sub>U]<sub>6</sub>(μ-κ<sup>1</sup>:κ<sup>2</sup>-CO<sub>3</sub>)<sub>6</sub>, is isolated as well as the bis(carboxylate)
complexes (C<sub>5</sub>Me<sub>5</sub>)<sub>2</sub>U[κ<sup>2</sup>-<i>O</i>,<i>O</i>′-O<sub>2</sub>CCH<sub>2</sub>C(R)CH<sub>2</sub>]<sub>2</sub>. The polymetallic
carbonate complex can also be synthesized from [(C<sub>5</sub>Me<sub>5</sub>)<sub>2</sub>U]<sub>2</sub>(μ-η<sup>6</sup>:η<sup>6</sup>-C<sub>6</sub>H<sub>6</sub>) and [(C<sub>5</sub>Me<sub>5</sub>)<sub>2</sub>U][(μ-Ph)<sub>2</sub>BPh<sub>2</sub>] and CO<sub>2</sub>
