(C5Me4H)1−-based reduction of dinitrogen by the mixed ligand tris(polyalkylcyclopentadienyl) lutetium and yttrium complexes, (C5Me5)3−x(C5Me4H)xLn

Abstract

Synthesis of the mixed ligand complexes (C₅Me₅)(C₅Me₄H)₂Ln (Ln = Lu, Y) for comparison with (C₅Me₅)₂(C₅Me₄H)Ln to evaluate details of steric effects on reductive reactivity has revealed that (C₅Me₅)_3−x(C₅Me₄H)_xLn complexes can reduce dinitrogen to (NN)²⁻. (C₅Me₅)(C₅Me₄H)₂Lu reacts with N₂ to form [(C₅Me₅)(C₅Me₄H)Lu]₂(μ-η²:η²-N₂), (C₅Me₅)₂(C₅Me₄H)Y reduces N₂ to [(C₅Me₅)₂Y]₂(μ-η²:η²-N₂), and (C₅Me₄H)₃Sc converts N₂ to [(C₅Me₄H)₂Sc]₂(μ-η²:η²-N₂). Exclusive (C₅Me₄H)¹⁻ loss occurs in each case with formation of (C₅Me₄H)₂ as the byproduct. (C₅Me₅)₂, the signature byproduct of sterically induced reduction reactions, is not observed. Since these complexes do not exhibit unusual steric parameters and since the more crowded (C₅Me₅)₂(C₅Me₄H)Lu and (C₅Me₅)₃Y do not display analogous reactivity, these reactions do not appear to be sterically induced reductions and suggest a new type of ligand-based reduction pathway involving (C₅Me₄H)¹⁻.