The reactivity of Samarium(II) in a Bis(indenyl) coordination environment

The reactivity of the organosamarium(II) indenyl complex (C 9 H 7 ) 2 Sm(THF) x , 1, has been compared with that of (C 5 Me 5 ) 2 Sm(THF) 2 , 2, and (C 5 Me 5 ) 2 Sm, 3, by examination of characteristic organosamarium(II) reactions which form trivalent oxide, iodide, cyclo‐octatetraenyl and azobenzene complexes. Complex 1 reacts with excess N 2 O to form [(C 9 H 7 ) 2 Sm(THF)] 2 (μ‐O), 4, and (C 9 H 7 ) 3 Sm(THF), 5, as the major products. Two equivalents of 1 react with one equivalent of 1,2‐di‐iodoethane in THF to give (C 9 H 7 )SmI 2 (THF) 2 , 6, as well as 5. Complex 1 reacts with 1,3,5,7‐cyclo‐octatetraene in a 2:1 ratio in THF to form 5 and (C 9 H 7 )Sm(C 8 H 8 )(THF) x , 7, which has been fully characterized as the 2,2′‐bipyridine adduct (C 9 H 7 )Sm(C 8 H 8 )(C 10 H 8 N 2 ), 7a. The reaction of 1 with azobenzene in a 2:1 ratio forms [(C 9 H 7 )Sm(N 2 Ph 2 )(THF)] x , 8, and 5. Complexes 4–6 and 7a have been definitively identified by X‐ray crystallography. Complex 4 crystallizes from THF in space group P 1― [C ; No. 2] with unit cell parameters at 163 K of a = 8.072(2) Å, b = 9.502(2) Å, c = 12.250(3) Å, α = 101.42(2)°, β = 90.71(2)°, γ = 102.50(2)°, V = 897.7(4) Å 3 and Z = 1 for D calcd = 1.704 Mgm −3 . Least‐squares refinement of the model based on 3924 reflections (| F 0 |)>3.0 σ (| F 0 |)) converged to a final R F =2.4%. The geometry around each Sm atom is a distorted tetrahedron and the Sm–O–Sm angle is 180°. Complex 5 crystallizes from THF/hexanes at −35°C in space group P 6 3 [ C ; No. 173] with unit cell parameters at 163 K of a = 11.7370(14) Å, c = 10.1994(12) Å, V = 1216.8(3) Å 3 and Z = 2 for D calcd = 1.550 Mg m −3 . Least‐squares refinement of the model based on 976 reflections (|F 0 |> 3.0σ (| F 0 |) converged to a final R F = 2.3%. The three ring centroids and the THF oxygen atom define a distorted tetrahedron around samarium with a (ring centroid)–Sm–(ring centroid) angle of 116.0°. Complex 6 crystallizes from THF/hexanes as the trisolvate (C 9 H 7 )SmI 2 (THF) 3 , 6a, in space group P 2 1 / n [C ; No. 14] with unit cell parameters at 163 K of a = 8.3969(12) Å, b = 17.165(5) Å, c = 33.592(7) Å, β = 96.468(15)°, V = 4811(2) Å 3 and Z = 8 for D calcd = 2.031 Mg m −3 . Least‐squares refinement of the model based on 5664 reflections (|F 0 |> 2.0 σ (|F 0 |)) converged to a final R F = 3.3%. The six ligands around Sm in 6a describe a distorted octahedron. The iodide ligands are trans to each other with a 153.8(1)° I–Sm–I angle. Adduct 7a crystallizes from hot THF/toluene in space group P 1 [ C ; No. 2] with a unit cell parameters at 163 K of a = 7.886(7) Å, b = 16.72(2) Å, c = 17.48(2) Å, α = 62.96(7)°, β = 85.17(7)°, γ = 85.23(9)°, V = 2042(3) Å 3 and Z = 4. The cyclooctateraenyl and indenyl ligands generate a bent metallocene structure for 7a which contains a chelating bipyridyl group in the plane bisecting the two rings.