Synthesis, Structure, and Reaction Chemistry of Samarium(II), Europium(II), and Ytterbium(II) Complexes of the Unsymmetrical Benzamidinate Ligand [PhC(NSiMe₃)(NC₆H₃Pr^<i>i</i>₂-2,6)]⁻

Neutral mononuclear lanthanide(II) bis(amidinate) complexes [LnL2(THF)x] [L = PhC(NSiMe3)(NC6H3Pri2-2,6)−; Ln = Sm, x = 2 (3); Ln = Eu, x = 2, (4); Ln = Yb, x = 1 (5)] were synthesized by the reaction of the appropriate LnI2(THF)2 with potassium amidinate [KL]n (2). The reduction chemistry of 3−5 was also examined. The reaction of the Sm(II) and Eu(II) amidinates 3 and 4 with diphenyl dichalcogenides PhEEPh (E = Se, Te) led to the binuclear lanthanide(III) amidinate-chalcogenolate complexes [LnL2(μ-EPh)]2 [Ln = Sm, E = Se (6); Ln = Eu, E = Se (7); Ln = Sm, E = Te (9)], whereas reacting the Yb(II) bis(amidinate) 5 with PhSeSePh yielded the mononuclear [YbL2(SePh)(THF)] (8). The reaction of 5 with iodine led to the Yb(III) bis(amidinate) iodide complex [YbL2(I)(THF)] (10). Treatment of 3 with N,N′-dicyclohexylcarbodiimide afforded the mixed-ligand Sm(III) tris(amidinate) [SmL2{CyNC(H)NCy}] (11) (Cy = cyclohexyl). The molecular structures of complexes 2−5 and 7−11 were elucidated by X-ray diffraction analyses.