One-step synthesis of heteroleptic rare-earth amide complexes featuring fluorenyl-tethered N-heterocyclic carbene ligands

Abstract

Reaction of the fluorenyl-tethered imidazolium bromide salt [9-(C13H9)C2H4N(CH)C2H2N(Me)][Br] (I) with [Y{N(SiMe3)2}3] generated the heteroleptic yttrium complex [Y{(η5-C13H8)C2H4N(κ-C)C2H2N(Me)}(Br){N(SiMe3)2}] (1), which contains an Y centre with a piano-stool geometry and four different donors. The reaction of I with [Nd{N(SiMe3)2}3] led to single crystals of the dimeric Nd complex [Nd{(η5-C13H8)C2H4N(κ-C)C2H2N(Me)}(μ-Br){N(SiMe3)2}]2 (2), likely due to the larger ionic radius of Nd3+. Reactions of I with [La{N(SiMe3)2}3], which contains the larger La3+ ion, demonstrated the formation of multiple products from ligand redistribution, including [La{(η5-C13H8)C2H4N(κ-C)C2H2N(Me)}{N(SiMe3)2}2] (3) and [La{(η5-C13H8)C2H4N(κ-C)C2H2N(Me)}2(Br)] (4).