Synthesis, reactivity, and stability of di- and trivalent samarium amides

SmCl3(HF)(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(mu-Cl)(THF)](2) (1) in 80% yield, whereas reaction with (i-Pr)(2)NLi under similar conditions gave [(i-Pr2N)(2)SmCl3(Li(TMEDA))(2)] (2). Partial loss of THF from complex 1 reorganized the molecule into the tetranuclear (Cy(2)N)(6)SmCl6(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 = CH2C(CH3)(3); Nf = CH2C(CH3)(2)Ph]. Direct synthesis of Sm(II) amides from SmI2(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: C56H105N4O2Sm2Cl2, triclinic, <P(1)over bar>, a = 14.344(1) Angstrom, b = 23.897(2)Angstrom, c = 10.2031(9) Angstrom, alpha = 88.479(9)degrees. beta = 121.83(1)degrees, gamma = 93.73(1)degrees, Z = 2. 2: C24H60N6SmCl3Li2 triclinic, <P(1)over bar>, a = 11.552(1) Angstrom, b = 15.483(1) Angstrom, c = 11.330(1) Angstrom, alpha = 101.69(1)degrees, beta = 106.13(1)degrees, gamma = 88.89(2)degrees. 3: C80H148N6Cl6O2Sm4, triclinic, <P(1)over bar>, a = 16.508(1) Angstrom, b = 16.7795(9) Angstrom, c = 16.4030(8) Angstrom, a = 89.794(1)degrees, beta = 88.688(2)degrees, gamma = 79.531(1)degrees, Z = 2. 4: C56H106N4O2LiSm, orthorhombic, Pna2(1), a = 16.6145(9) Angstrom, b = 17.5858(9) Angstrom, c = 19.7754(9) Angstrom, V = 5778.0(9) Angstrom(3), Z = 4. 5: C47H82N3OSm, monoclinic, P2(1)/c, a = 10.250(2) Angstrom, b = 23.305(2) Angstrom, c = 19.088(1) Angstrom, B = 100.90(1)9 Z = 4. 6: C60H72N(8)SmNa2, tetragonal. I4(1)/acd, a = 18.0004(9) Angstrom, c = 34.106(1) Angstrom, Z = 8. 7: C44H60N2O5Sm, monoclinic, C2, a = 19.066(1) Angstrom, b = 11.932(1) Angstrom, c = 9.200(1) Angstrom, P = 93.89(1)degrees, Z = 2.