Mixed‐Donor Amido–Siloxo Actinide(IV) Halide and Alkyl Complexes with an Aryl Cipso Interaction

Abstract

AbstractThe synthesis and characterisation of a series of new actinide(IV) complexes supported by the mixed‐donor amido–amino–siloxo framework [RN(Li)SiMe2N(R)SiMe2OLi] ([RNNO]Li2; R = 2,4,6‐Me3Ph, 2,6‐iPr2Ph) are presented. The reaction of 1 equiv. of [RNNO]Li2 with ThCl4·2DME (DME = 1,2‐dimethoxyethane) in DME generated {Li·nDME}{[RNNO]2Th2Cl5} (1: R = 2,4,6‐Me3Ph, n = 2; 2: R = 2,6‐iPr2Ph, n = 3) in high yield, and the addition of [NNO]Li2 to UCl4 in tetrahydrofuran (THF) resulted in the formation of {[NNO]UCl3Li·THF}2 (3). The structures of 1–3 indicate that they retain LiCl as “ate” complexes. The addition of 2 equiv. of [NNO]Li2 to ThCl4·2DME and UCl4 gives the bis‐ligated complexes [NNO]2ThClLi (4) and [NNO]2U (5), respectively. In 1–5, the [RNNO]2– ligands all coordinate through the amido and siloxo donors as well as the ipso carbon atom of the phenyl group of the amido ligand but not through the central amino group. Complex 3 can be alkylated through the addition of 2 equiv. of LiCH2SiMe3 to give [NNO]U(CH2SiMe3)2 (6) or NaCp (Cp = cyclopentadienyl) to give [NNO]UCp2 (7); the latter has been structurally characterised.