Synthesis, structure and bonding of hexaphenyl thorium(iv): observation of a non-octahedral structure

Abstract

We report herein the synthesis of the first structurally characterized homoleptic actinide aryl complexes, [Li(DME)₃]₂[Th(C₆H₅)₆] (1) and [Li(THF)(12-crown-4)]₂[Th(C₆H₅)₆] (2), which feature an anion possessing a regular octahedral (1) or a severely distorted octahedral (2) geometry. The solid-state structure of 2 suggests the presence of pseudo-agostic ortho C–H⋯Th interactions, which arise from σ(C–H) → Th(5f) donation. The non-octahedral structure is also favoured in solution at low temperatures.