Heteroleptic Lanthanide Complexes with Aryloxide Ligands. Synthesis and Structural Characterization of Divalent and Trivalent Samarium Aryloxide/Halide and Aryloxide/Cyclopentadienide Complexes

Synthesis of a new class of heteroleptic samarium aryloxide complexes has been achieved by the use of homoleptic samarium(II) bis(aryloxide) Sm(OAr)₂(THF)₃ (1, Ar = C₆H₂Bu^t₂-2,6-Me-4) as a starting material, which is easily obtained by reaction of Sm(N(SiMe₃)₂)₂(THF)₂ with 2 equiv of ArOH in THF. 1 reacts with 1 equiv of SmI₂ in THF to give Sm(II) mixed aryloxide/iodide [(ArO)Sm(μ-I)(THF)₃]₂ (2), which adopts a dimeric structure via very weak Sm···I (3.534(2) Å) interactions. Reaction of 2 with C₅Me₅K in THF/HMPA affords the corresponding Sm(II) aryloxide/cyclopentadienide (C₅Me₅)Sm(OAr)(HMPA)₂ (3). Oxidation of 1 with 0.5 equiv of I₂ in THF gives monomeric samarium(III) aryloxide/iodide (ArO)₂SmI(THF)₂ (4), while the similar reaction of 1 with ClCH₂CH₂Cl or ^tBuCl in THF affords dimeric samarium(III) aryloxide/chloride [(ArO)₂Sm(μ-Cl)(THF)]₂ (5). Crystal data for 1:  monoclinic, space group P2₁, a = 9.903(3) Å, b = 16.718(5) Å, c = 13.267(2) Å, β = 95.17(2)°, V = 2187(2) ų, Z = 2, D_c = 1.223 g cm^-3, R = 0.0634. Crystal data for 2·2THF:  monoclinic, space group P2₁/a, a = 18.330(6) Å, b = 14.320(4) Å, c = 13.949(3) Å, β = 103.16(2)°, V = 3563(2) ų, Z = 2, D_c = 1.46 g cm^-3, R = 0.0606. Crystal data for 3:  triclinic, space group P1̄, a = 10.528(1) Å, b = 12.335(2) Å, c = 19.260(2) Å, α = 101.33(1)°, β = 95.230(9)°, γ = 108.54(1)°, V = 2293.1(5) ų, Z = 2, D_c = 1.25 g cm^-3, R = 0.0358. Crystal data for 4:  monoclinic, space group C2/c, a = 17.191(7) Å, b = 10.737(6) Å, c = 21.773(7) Å, β = 98.80(3)°, V = 3971(3) ų, Z = 4, D_c = 1.44 g cm^-3, R = 0.0467. Crystal data for 5:  monoclinic, space group P2₁/n, a = 13.750(3) Å, b = 17.231(3) Å, c = 14.973(6) Å, β = 95.81(2)°, V = 3529(2) ų, Z = 2, D_c = 1.31 g cm^-3, R = 0.0557.