Samarium and ytterbium complexes based on sterically hindered 1,2-bis(imino)acenaphthene

Reactions of the samarium complex [(Ar BIG -bian) 2− Sm 2+ ] ( 1 ) (Ar BIG -bian is the 1,2-bis-[(2,6-dibenzhydryl-4-methylphenyl)imino]acenaphthene dianion) with iodine (0.5 mol. equiv.) or triphenyltin chloride lead to the oxidation of the metal and afford the corresponding derivatives [(Ar BIG -bian) 2− Sm 3+ I(dme)] ( 2 ) and [(Ar BIG -bian) 2− Sm 3+ Cl(dme)] ( 3 ). Meanwhile, the reaction of the related ytterbium complex [(Ar BIG -bian) 2− Yb 2+ (dme)] ( 4 ) with iodine (2:1) or copper(I) chloride resulted in the oxidation of the dianionic ligand rather than the metal to form the compounds [(Ar BIG -bian) − Yb 2+ I(dme)] ( 5 ) and [(Ar BIG -bian) − Yb 2+ Cl] 2 ( 6 ), respectively. The reaction of 2 with one molar equivalent of potassium pentamethylcyclopentadienide gave the adduct [(Ar BIG -bian) 2− Sm 3+ (I)Cp*][K(dme) 4 ] ( 7 ). The reaction of samarium complex 1 with 2,2′-bipyridine (bipy) (1:2) is accompanied by the oxidation of Sm II to Sm III to form the derivative [(Ar BIG -bian) 2− Sm 3+ (bipy) 2 ] ( 8 ) containing the radical-anion and neutral bipy ligands. The coordination of a neutral bipyridine molecule to the metal atom in ytterbium iodine complex 5 leads to the metal—ligand electron transfer giving [(Ar BIG -bian) 2− Yb 3+ I(bipy)] ( 9 ). All the newly synthesized compounds 2, 3 , and 5–9 were characterized by IR spectroscopy (complexes 5 and 6 were also characterized by EPR spectroscopy) and elemental analysis. The molecular structures of complexes 2, 3 , and 5–9 were determined by X-ray diffraction.