Selective Oxidation of a Single Metal Site of Divalent Calix[4]pyrrolide Compounds [Ln 2 (N 4 Et 8 )(thf) 4 ] (Ln = Sm or Eu), Giving Mixed Valent Lanthanoid(II/III) Complexes.

The samarium(II) calix[4]pyrrolide complex [Sm 2 (N 4 Et 8 )(thf) 4 ] (N 4 Et 8 = meso -octaethylcalix[4]pyrrolide) undergoes selective oxidation of one Sm II site on reaction with a range of metal carbonyls giving mixed valence Sm(II/III) complexes. Thus, reactions with TM(CO) 6 (TM = Mo or Cr) entrap M 2 (CO) 10 2- ions between two mixed valence hosts in [{(thf) 2 Sm II (N 4 Et 8 )Sm III (thf)(μ-OC)TM(CO) 4 } 2 ]·PhMe (TM = Mo, 1 ; Cr, 2 ), while W(CO) 6 on a different stoichiometry traps W(CO) 5 2- in [{(thf) 2 Sm II (N 4 Et 8 )Sm III } 2 {(μ-OC)W(CO) 4 }]·PhMe 3 in which the isocarbonyl group is disordered over two sites. In contrast, [Sm 2 (N 4 Et 8 )(thf) 4 ] reacts with dicobalt octacarbonyl, bis (cyclopentadienyl)tetracarbonyl diiron, and dimanganese decacarbonyl to give the mixed valence species [(thf) 2 Sm II (N 4 Et 8 )Sm III (thf)(μ-OC)TM(CO) 3 ]·2PhMe (TM = Co, 4 ; Fe, 5 ) and [(thf) 2 Sm II (N 4 Et 8 )Sm III (thf)(μ-OC)Mn(CO) 4 ]·1.5PhMe 6 . However, both Sm II sites of [Sm 2 (N 4 Et 8 )(thf) 4 ] can be oxidized as its reaction with cyclooctatetraene (COT) yields the Sm III species [(thf)Sm III (N 4 Et 8 )Sm III (COT)] 7 . The analogous Eu II reagent, [Eu 2 (N 4 Et 8 )(thf) 4 ] induces C-halogen activation of perfluorodecalin, hexachloroethane, and bromoethane to form the mixed oxidation state species [(thf) 2 Eu II (N 4 Et 8 )Eu III (μ-X)] 2 (X = F, 8 ; Cl, 9 ; Br, 10 ) despite the use of a sufficient reagent to oxidize both Eu II sites. The synthetic potential of the halogenido complexes was illustrated by the reaction of 10 with sodium bis (trimethylsilyl)amide to give the mixed oxidation state [(thf) 2 Eu II (N 4 Et 8 )Eu III (N(SiMe 3 ) 2 )] 11 .