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

Re-examination of the X-ray structure of the imido As(III) complex previously formulated as [{As((NBu)-Bu-t)(3)}(2)Li-6].benzene (1.benzene) indicates that the disorder within the [{As((NBu)-Bu-t)(3)}(2)Li-6] cage can be better explained by the molecular formulae [{As((NBu)-Bu-t)(3)}(2)Li-6].[(LiNHBu)-Bu-t](6) or [{As((NBu)-Bu-t)(3)}Li-3.((BuNHLi)-Bu-t)(3)]. The syntheses and X-ray structures of the new complexes [{As(N(2-MeO-C6H4)(3))}(2)Li-6.2TMEDA] (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(mu-NCy)](2) (5) with PhCH2NHLi (1 : 6 equivalents) led to the unexpected formation of Zintl compounds containing the As-7(3-) anion. The X-ray structure of [As7Li3.3(CyNH2).3thf] 6 is also reported.