Synthesis, structures and coordination behaviour of [As(NR)3]3− trianions

Abstract

Re-examination of the X-ray structure of the imido As(III) complex previously formulated as [{As(N^tBu)₃}₂Li₆]·benzene (1·benzene) indicates that the disorder within the [{As(N^tBu)₃}₂Li₆] cage can be better explained by the molecular formulae [{As(N^tBu)₃}₂Li₆]·[LiNH^tBu]₆ or [{As(N^tBu)₃}Li₃·(^tBuNHLi)₃]. The syntheses and X-ray structures of the new complexes [{As(N(2-MeO-C₆H₄)₃)}₂Li₆·2TMEDA] (3) and [As{N(2-py)}₃·LiN(2-py)·3thf]₂·2thf (4·2thf), containing [As(NR)₃]³⁻ anions, are reported. Attempts to prepare the heteroleptic trianion [As(NCy)₂(NCH₂Ph)]₃⁻via reaction of the arsazane dimer [CyNHAs(μ-NCy)]₂ (5) with PhCH₂NHLi (1 ∶ 6 equivalents) led to the unexpected formation of Zintl compounds containing the As₇³⁻ anion. The X-ray structure of [As₇Li₃·3(CyNH₂)·3thf] 6 is also reported.