Structural Diversity and Multielectron Reduction Reactivity of Samarium(II) Iodido-β-diketiminate Complexes Dependent on Tetrahydrofuran Content.

The molecular structures of complexes [Sm(Nacnac)I(thf) n ] (Nacnac = HC(C(Me)Ndipp) 2 - , dipp = 2,6-diisopropylphenyl, thf = tetrahydrofuran) depending on the number of thf ligands are studied. The complete removal of thf from a known complex [Sm(Nacnac)I(thf) 2 ] leads to a tetranuclear product [Sm(Nacnac)I] 4 ( 4 ). The partial removal of thf results in mixtures of dinuclear [Sm 2 (Nacnac) 2 I 2 (thf)] ( 2 ), trinuclear [Sm 3 (Nacnac) 3 I 3 (thf)] ( 3 ), and tetranuclear [Sm 4 (Nacnac) 4 I 4 (thf) 2 ] ( 4* ) complexes and 4 , depending on the conditions. The reaction of solvent-free SmI 2 with 1 equiv of K(Nacnac) results mainly in [Sm(Nacnac) 2 ] ( 1 ), while the interaction of 4 with certain amounts of thf allows obtaining pure 2 and 3 (with the admixture of 4* ). Complex 4* is the exact dimer of 2 , and both compounds are stable in solutions. Reactions with 3 and 4 as reductants are studied. 4 is oxidized by I 2 to stoichiometrically yield two products, mixed-valent tetranuclear [Sm 4 (Nacnac) 4 I 5 ] ( 5 ) and binuclear [Sm(Nacnac)I 2 ] 2 ( 6 ) complexes. In the reaction of 4 with n Bu 3 PTe, a trinuclear complex [Sm 3 (Nacnac) 3 (μ-I) 3 (μ 3 -E) 2 ] ( 8 , E = I or Te) is formed in small amounts, with the formation of 6 as the second product. 3 serves as a two-electron reductant in the reaction with n Bu 3 PTe to yield a trinuclear complex [Sm 3 (Nacnac) 3 I 3 (μ-Te 2 )] ( 7 ). Complexes 2 , 4 , 4* , 5 , 6 , and 8 possess a unique flat Sm x I y core of heavy atoms, which is assumed to be a consequence of the Nacnac ligand geometry.