Actinide‐Pnictide Chemistry: A Uranium Primary Alkyl Stibinide and a Diuranium Hexaantimonide‐Tetralithium Zintl Cluster

Abstract

AbstractStructurally characterised U−Sb bonds are rare. Here, the synthesis and characterisation of [U(TrenDMBS){Sb(H)C(H)(SiMe3)2}] (5, TrenDMBS=N(CH2CH2NSiMe2But)3) and [{U(TrenTIPS)}2{Sb3(μ6‐Li)(μ‐Li[THF]2)3Sb3}] (6, TrenTIPS=N(CH2CH2NSiPri3)3) are reported. Complex 5 is an unprecedented primary stibinide actinide complex and 6 can be formulated as containing a unique triple decker 20 skeletal‐electron distorted closo tricapped Zintl cluster (Sb3Li4Sb3)2− that is analogous to the D3h closo tricapped trigonal prism form of [Ge9]2−. Quantum chemical calculations emphasise polar U−Sb bonding in 5 and 6, and that viewing (Sb3Li4Sb3)2− as a single unit rather than two distinct but contiguous (Sb3)3− units, themselves unprecedented in molecular actinide chemistry, is valid due to the presence of three weak (Sb3)⋯(Sb3) (3, −1)‐bond critical points. Complexes 5 and 6 highlight the challenges of preparing polar U−Sb bonds and the underlying tendency for unpredictable cluster formation with Sb.