Synthesis and reactivity of neodymium(III) amido-tethered N-heterocyclic carbene complexes

The reaction of the heteroleptic Nd(III) iodide, [Nd(L')(N '')(mu-I)] with the potassium salts of primary aryl amides [KN(H)Ar'] or [KN(H)Ar*] affords heteroleptic, structurally characterised, low-coordinate neodymium amides [Nd(L')(N '')(N(H)Ar')] and [Nd(L')(N '')(N(H)Ar*)] cleanly(L' = t-BuNCH(2)CH(2)[C{NC(SiMe(3))CHNt-Bu}], N '' = N(SiMe(3))(2), Ar' = 2,6-Dipp(2)C(6)H(3), Dipp = 2,6-Pr(2)(i)C(6)H(3), Ar* = 2,6-(2,4,6-Pr(3)(i)C(6)H(2))(2)C(6)H(3)). The potassium terphenyl primary amide [KN(H)Ar*] is readily prepared and isolated, and structurally characterised. Treatment of these primary amide-containing compounds with alkali metal alkyl salts results in ligand exchange to give alkali metal primary amides and intractable heteroleptic Nd(III) alkyl compounds of the form [Nd(L')(N '')(R)] (R = CH(2)SiMe(3), Me). Attempted deprotonation of the Nd-bound primary amide in [Nd(L')(N '')(N(H)Ar*)] with the less nucleophilic phosphazene superbase Bu'N = P{N = P(NMe(2))(3)}(3) resulted in indiscriminate deprotonations of peripheral ligand CH groups.