Synthesis and Insertion Chemistry of Mixed Tether Uranium Metallocene Complexes

AbstractThe synthesis of mixed tethered alkyl uranium metallocenes has been investigated by examining the reactivity of the bis(tethered alkyl) metallocene [(η5‐C5Me4SiMe2CH2‐κC)2U] (1) with substrates that react with only one of the UC linkages. The effect of these mixed tether coordination environments on the reactivity of the remaining UC bond has been studied by using CO insertion chemistry. One equivalent of azidoadamantane (AdN3) reacts with 1 to yield the mixed tethered alkyl triazenido complex [(η5‐C5Me4SiMe2CH2‐κC)U(η5‐C5Me4SiMe2‐CH2NNN‐Ad‐κ2N1,3)]. Similarly, a single equivalent of CS2 reacts with 1 to form the mixed tethered alkyl dithiocarboxylate complex [(η5‐C5Me4SiMe2CH2‐κC)U(η5‐C5Me4SiMe2‐ CH2C(S)2‐κ2S,S′)], a reaction that constitutes the first example of CS2 insertion into a U4+C bond. Complex 1 reacts with one equivalent of pyridine N‐oxide by CH bond activation of the pyridine ring to form a mixed tethered alkyl cyclometalated pyridine N‐oxide complex [(η5‐C5Me4SiMe2CH2‐κC)(η5‐C5Me4SiMe3)U(C6H4NO‐κ2C,O)]. The remaining (η5‐C5Me4SiMe2CH2‐κC)2− ligand in each of these mixed tethered species show reactivity towards CO and tethered enolate ligands form by insert