SYNTHESIS AND REACTIVITY OF BIS(TRIMETHYLSILYL)CYCLOPENTADIENYL SAMARIUM COMPLEXES INCLUDING THE X-RAY CRYSTAL-STRUCTURE OF [(ME3SI)2C5H3]3SM

SmI2(THF)2 reacts with two equivalents of K[1,3-(Me3Si)2C5H3] to form [(Me3Si)2C5H3]2Sm(THF) (1). 1 can be desolvated by sublimation at 80°C and 4 × 10-6 Torr to give [(Me3Si)2C5H3]2Sm (2). 1 polymerizes ethylene and reacts under 90 psi of CO to form [(Me3Si)2C5H3]3Sm (3) which can also be synthesized directly from SmCl3 and KC5H3(SiMe3)2. 3 crystallizes from toluene in space group P21/c with unit cell dimensions a = 17.961(3), b = 13.748(2), c = 19.327(3) Å, β = 112.80(1)°, V = 4397.9(11) Å3 and Z = 4 for Dcalcd = 1.17 g cm-3. Least squares refinement on the basis of 6173 observed reflections led to a final RF value of 5.3%. The three 1,3-(Me3Si)2C5H3 ring-centroids form a trigonal plane around the samarium center with an average SmC(ring) distance of 2.76(4) Å. The silyl-substituted part of each ring is tilted away from the samarium atoms such that individual SmC distances vary from 2.698(5) to 2.806(5) Å within the same ring. © 1990.