title: Synthesis and insertion chemistry of mixed tether uranium metallocene complexes.
abstract: The synthesis of mixed tethered alkyl uranium metallocenes has been investigated by examining the reactivity of the bis(tethered alkyl) metallocene [(η(5)-C(5)Me(4)SiMe(2)CH(2)-κC)(2)U] (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 (AdN(3)) reacts with 1 to yield the mixed tethered alkyl triazenido complex [(η(5)-C(5)Me(4)SiMe(2)CH(2)-κC)U(η(5)-C(5)Me(4)SiMe(2)-CH(2)NNN-Ad-κ(2)N(1,3))]. Similarly, a single equivalent of CS(2) reacts with 1 to form the mixed tethered alkyl dithiocarboxylate complex [(η(5)-C(5)Me(4)SiMe(2)CH(2)-κC)U(η(5)-C(5)Me(4)SiMe(2)-CH(2)C(S)(2)-κ(2)S,S')], a reaction that constitutes the first example of CS(2) insertion into a U(4+)-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 [(η(5)-C(5)Me(4)SiMe(2)CH(2)-κC)(η(5)-C(5)Me(4)SiMe(3))U(C(6)H(4)NO-κ(2)C,O)]. The remaining (η(5)-C(5)Me(4)SiMe(2)CH(2)-κC)(2-) ligand in each of these mixed tethered species show reactivity towards CO and tethered enolate ligands form by insertion. Subsequent rearrangement have been identified in [(η(5)-C(5)Me(4)SiMe(3))U(C(5)H(4)NO-κ(2)C,O)(η(5)-C(5)Me(4)SiMe(2)C(=CH(2))O-κO)] and [(η(5)-C(5)Me(4)SiMe(2)CH(2)NNN-Ad-κ(2)N(1,3))U(η(5)-C(5)Me(4)SiMe(2)C(=CH(2))O-κO)].
authors.affiliation: Department of Chemistry, University of California, Irvine, 92627-2025, USA.
authors.forename: Nathan A
authors.initials: NA
authors.lastname: Siladke
authors.forename: Jennifer
authors.initials: J
authors.lastname: LeDuc
authors.forename: Joseph W
authors.initials: JW
authors.lastname: Ziller
authors.forename: William J
authors.initials: WJ
authors.lastname: Evans