Synthesis, Reactivity, and Stability of Di- and Trivalent Samarium Amides

SmCl 3 (THF) 3 (THF = tetrahydrofuran) reacts with anionic dialkylamides R 2 N - [R = Cy (cyclohexyl), i-Pr (isopropyl), Ph (phenyl)] to give different products, depending on the nature of the R substituents. Reaction with Cy 2 NLi in a 1:2 molar ratio formed [(Cy 2 N) 2 Sm(μ-Cl)(THF)] 2 ( 1 ) in 80% yield, whereas reaction with (i-Pr) 2 NLi under similar conditions gave [(i-Pr 2 N) 2 SmCl 3 (Li(TMEDA)) 2 ] ( 2 ). Partial loss of THF from complex 1 reorganized the molecule into the tetranuclear (Cy 2 N) 6 Sm 4 Cl 6 (THF) 2 ( 3 ). Attempts to reduce complex 1 with a number of reagents gave [(Cy 2 N) 3 SmTHF]·toluene ( 5 ), while [(Cy 2 N) 4 SmLi(THF)] ( 4 ) was isolated upon alkylation reactions carried out with either NpLi or NfLi [Np = CH 2 C(CH 3 ) 3; Nf = CH 2 C(CH 3 ) 2 Ph]. Direct synthesis of Sm(II) amides from SmI 2 (THF) 2 starting material was successful only in the case of diphenylamide anion (Ph 2 N - ). Depending on the stoichiometry, -ate (Ph 2 N) 4 Sm[Na(TMEDA)] 2 ( 6 ) or neutral [(Ph 2 N) 2 Sm(THF) 4 ]·THF ( 7 ) was obtained. The crystal structures of 1 − 7 were demonstrated by X-ray diffraction analysis. Crystal data are as follows. 1: C 56 H 105 N 4 O 2 Sm 2 Cl 2, triclinic, P 1̄, a = 14.344(1) Å, b = 23.897(2) Å, c = 10.2031(9) Å, α = 88.479(9)°, β = 121.83(1)°, γ = 93.73(1)°, Z = 2. 2: C 24 H 60 N 6 SmCl 3 Li 2 triclinic, P 1̄, a = 11.552(1) Å, b = 15.483(1) Å, c = 11.330(1) Å, α = 101.69(1)°, β = 106.13(1)°, γ = 88.89(2)°. 3: C 80 H 148 N 6 Cl 6 O 2 Sm 4, triclinic, P 1̄, a = 16.508(1) Å, b = 16.7795(9) Å, c = 16.4030(8) Å, α = 89.794(1)°, β = 88.688(2)°, γ = 79.531(1)°, Z = 2. 4: C 56 H 106 N 4 O 2 LiSm, orthorhombic, Pna 2 1, a = 16.6145(9) Å, b = 17.5858(9) Å, c = 19.7754(9) Å, V = 5778.0(9) Å 3, Z = 4. 5: C 47 H 82 N 3 OSm, monoclinic, P 2 1 / c, a = 10.250(2) Å, b = 23.305(2) Å, c = 19.088(1) Å, β = 100.90(1)°, Z = 4. 6: C 60 H 72 N 8 SmNa 2, tetragonal, I 4 1 / acd, a = 18.0004(9) Å, c = 34.106(1) Å, Z = 8. 7: C 44 H 60 N 2 O 5 Sm, monoclinic, C 2, a = 19.066(1) Å, b = 11.932(1) Å, c = 9.200(1) Å, β = 93.89(1)°, Z = 2.