Crystalline di- or trianionic metal (Al, Sm) β-diketiminates

Abstract

The new [Al(L^Tol)Br₂] (1) and the known [Al(L^Ph)Me₂] (2) were prepared as potential precursors to more novel aluminium compounds. In the event, only the latter was effective. Thus 2 and two equivalents of potassium was the source of [{Al(L^Ph)Me₂K₂(OEt₂)}₂] (3). The complexes [{KSm(L^Ph)₂}₂] (4), [Sm₂(L^Dph)₃] (5) and [Sm(L^Tol,Ad)(L^Tol,Ad−H)] (6) were obtained from SmI₂ and two equivalents of the appropriate potassium β-diketiminate [L^Ph or L^Tol or L^Dph = {N(SiMe₃)C(Ar)}₂CH, Ar = Ph or C₆H₄Me-4 or C₆H₄Ph-4; L^Tol,Ad = N(SiMe₃)C(C₆H₄Me-4)C(H)C(Ad)NSiMe₃, L^Tol,Ad−H = N(SiMe₃)C(C₆H₄Me-4)C(H)C(Ad)NSiMe₂CH₂, Ad = 1-adamantyl]. Crystalline complexes 3–6 were isolated in very low (4, 5) or satisfactory (3, 6) yield and characterised by X-ray diffraction. From comparisons of the M–N, N–C, C–C and C–C_Ar bond lengths with suitable standards, complexes 3–5 are assigned as containing Al³⁺/(L^Ph)³⁻ for 3, Sm³⁺/(L^Ph)⁻/(L^Ph)³⁻ for 4, and {Sm³⁺}₂/(L^Dph)⁻/(L^Dph)²⁻/(L^Dph)³⁻ for 5. Complex 6 is best formulated as a Sm³⁺ compound with one “normal” (L^Tol,Ad)⁻ and one deprotonated (L^Tol,Ad−H)²⁻ ligand.