Redox transmetallation approaches to the synthesis of extremely bulky amido-lanthanoid(II) and -calcium(II) complexes

Redox transmetallation protolysis reactions between HgPh2, elemental metals, M = Ca, Eu, or Yb, and the bulkyl arylsilylamine (LH)-L-Ph-H-dagger (HN(SiPh3)(Ar-dagger), Ar-dagger = C(6)H(2)Pri(dagger)C(H) Ph-2}(2)-4,2,6), or the borylsilylamine PhLBoH (HN(SiPh3){B(DipNCH)(2)}, Dip = C6H3Pr2i-2,6) pro-ligands yielded complexes incorporating doubly deprotonated, N, C-chelating amido/organyl ligands, viz. [M(L-H) (thf)(x)](n), L-H = Ph-L dagger-H (1-3) or L-Ph(Bo-H) (4-5); M = Ca (1, 4), Eu (2) or Yb (3, 5); x = 0 (5) or 2 (1-4); n = 1 (1-4) or 2 (5). Structural differences between 4 and 5 represent a rare divergence in the chemistry of divalent calcium and ytterbium. Utilisation of a less hindered bis(aryl) amine, (LH)-L-D-H-M (HN(Dip)(Mes), Mes = C6H2Me3-2,4,6) in a similar reaction yielded a threecoordinate, trigonal planar ytterbium complex [Yb(L-D(M))(2)(thf)] (6). Direct redox transmetallation reactions between an amido-mercurial iodide [(L-Me(dagger)) HgI] (7, L-Me(dagger) = -N(SiMe3)(Ar-dagger)) and ytterbium or europium metal afforded homoleptic [Yb(L-Me(dagger))(2)] (8) and heteroleptic [{Eu(L-Mc(dagger))(mu-I)(thf)}(2)] (9) respectively. This study highlights the versatility of redox transmetallation pathways to amido-lanthanoid complexes, especially where such compounds are difficult to access using conventional salt metathesis pathways.