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

Abstract

The reactivity of the organosamarium(II) indenyl complex (C9H7)2Sm(THF)x, 1, has been compared with that of (C5Me5)2Sm(THF)2, 2, and (C5Me5)2Sm, 3, by examination of characteristic organosamarium(II) reactions which form trivalent oxide, iodide, cyclo‐octatetraenyl and azobenzene complexes. Complex 1 reacts with excess N2O to form [(C9H7)2Sm(THF)]2(μ‐O), 4, and (C9H7)3Sm(THF), 5, as the major products. Two equivalents of 1 react with one equivalent of 1,2‐di‐iodoethane in THF to give (C9H7)SmI2(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 (C9H7)Sm(C8H8)(THF)x, 7, which has been fully characterized as the 2,2′‐bipyridine adduct (C9H7)Sm(C8H8)(C10H8N2), 7a. The reaction of 1 with azobenzene in a 2:1 ratio forms [(C9H7)Sm(N2Ph2)(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 P1― [C 11; 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) Å3 and Z = 1 for Dcalcd = 1.704 Mgm−3. Least‐squares refinement of the model based on 3924 reflections (|F0|)>3.0 σ (|F0|)) converged to a final RF=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 P63 [C 66; No. 173] with unit cell parameters at 163 K of a = 11.7370(14) Å, c = 10.1994(12) Å, V = 1216.8(3) Å3 and Z = 2 for Dcalcd = 1.550 Mg m−3. Least‐squares refinement of the model based on 976 reflections (|F0|> 3.0σ (|F0|) converged to a final RF = 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 (C9H7)SmI2(THF)3, 6a, in space group P21/n [C 2h5; 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) Å3 and Z = 8 for Dcalcd = 2.031 Mg m−3. Least‐squares refinement of the model based on 5664 reflections (|F0|> 2.0 σ (|F0|)) converged to a final RF = 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 P1 [C 11; 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) Å3 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.

Mono(cyclopentadienyl) Complexes of the Rare-Earth Metals

“…29 The indenyl complex [Ho(η 5 -C 9 H 7 )Cl 2 (THF) 3 ] was synthesized from HoCl 3 and Na(C 9 H 7 ) in THF, and its molecular structure was characterized by singlecrystal X-ray diffraction, showing the holmium atom with the common distorted octahedral, mer-trans configuration of type K. 30 In analogy to the reactions of related samarocene complexes [Sm(η 5 -C 5 R 5 ) 2 (THF) x ], 2 equiv of indenyl samarium(II) complex [Sm(η 5 -C 9 H 7 ) 2 (THF) x ] reacted with 1 equiv of 1,2-diiodoethane in THF to give [Sm- 3 ], displaying the common K-type configuration. 31 NdI 3 (THF) x reacted with 1 equiv of K(C 5 Me 5 ) to produce the mono(pentamethylcyclopentadienyl) complex [Nd(η 5 -C 5 Me 5 )I 2 (THF) 3 ] in moderate yield, which upon treatment with an excess of pyridine in toluene led to displacement of all the THF ligands and formation of the tris-pyridine adduct [Nd(η 5 -C 5 Me 5 )-I 2 (py) 3 ]. According to a single-crystal X-ray diffraction study, [Nd(η 5 -C 5 Me 5 )I 2 (py) 3 ] adopts the pseudooctahedral geometry of type K in the crystalline state.…”

“…Oxidation of [Sm(η 5 -C 9 H 7 ) 2 (THF) x ] with azobenzene gave a compound of composition [Sm(η 5 -C 9 H 7 )(N 2 Ph 2 )(THF)] x , which is expected to be analogous to the previously structurally characterized C 5 Me 5 analogue [Sm(η 5 -C 5 Me 5 )-(THF)(µ-η 2 :η 2 -N 2 Ph 2 )] 2 . 31 The crystallographically characterized 67 dimeric lutetium complex [Lu(η 5 -C 5 H 5 )-(THF)(µ-η 2 :η 2 -N 2 Ph 2 )] 2 was obtained by reaction between the naphthalenide complex [Lu(η 5 -C 5 H 5 )(C 10 H 8 )-(THF) 2 ] 68 or the anthracenide complex [Lu(η 5 -C 5 H 5 )-(C 14 H 10 )(THF) 2 ] 67 and azobenzene in THF and can be regarded as an analogous complex containing two bridging 1,2-diphenylhydrazido(2-) ligands.…”

A Holmium(III) `Carbons Adjacent' Carborane Cluster, [Li(C6H16N2)2][Li2(C6H16N2)2{HoCl2(C8H22B4Si2)2}].0.5C6H6

“…H atoms, except for those of the C2B4-cage atoms, and the exopolyhedral Li(TMEDA)2 unit are omitted for clarity. et al, 1995) and in the dinuclear Ho III 'carbons apart' carborane cluster , and similar to those of the d o Group 4 metallocene, lanthanocene and actinocene derivatives (Rogers & Rogers, 1991;Evans, 1985Evans, , 1987Wilkinson, Stone & Abel, 1982;Wilkinson, Gillard & McCleverty, 1987;Cotton & Wilkinson, 1988) as well as their carborane analogues . This work, together with our recent results on the analogous Er m carborane complex and the Ho In 'carbons apart' carborane sandwich complex, indicates that the reactivity of the lanthanide reagents with the carborane ligand systems is dependent upon the solvents in which the reactions are being carried out.…”

“…Nevertheless, it was speculated that the methoxide and 02-ions might be the decomposition products of a side-reaction between the solvent and the reactant species. This speculation is not entirely inconceivable when one considers the high reactivity and great oxophilicity of the lanthanide compounds in general (Evans, 1985). In order to verify whether thf is the actual source for both the O 2-and the OMeunits, we carried out a reaction between HoC13 and the TMEDA-solvated dilithiacarborane (I) in a 1:2 ratio in an exclusively nonoxygen-containing solvent, benzene, at 273 K. We obtained the title compound, (II), as an air-sensitive orange crystalline solid in over 90% yield (Hosmane et al, unpublished results).…”

A Dinuclear Holmium(III) `Carbons Apart' Carborane Cluster, [C34H92B8Cl4Ho2Li2N6Si4].C10H8

“…Although the bridging of the sandwiched metal atom (Hol in Fig. Nonetheless, the distorted tetrahedral geometry of the centrally located Ho atom (Hol. (Rogers & Rogers, 1991;Evans, 1985Evans, , 1987Wilkinson, Stone & Abel, 1982;Wilkinson, Gillard & McCleverty, 1987;Cotton & Wilkinson, 1988) and their carborane analogues known to date . Nonetheless, the distorted tetrahedral geometry of the centrally located Ho atom (Hol. (Rogers & Rogers, 1991;Evans, 1985Evans, , 1987Wilkinson, Stone & Abel, 1982;Wilkinson, Gillard & McCleverty, 1987;Cotton & Wilkinson, 1988) and their carborane analogues known to date .…”