Synthesis, structure and magnetism of bis[1,2,4-tris(trimethylsilyl)cyclopentadienyl]europium

Bis[tris(trimethylsilyl)cyclopentadienyl]europium, EU{C5H2[Si(CH3)(3)](3)}(2) (1), has been synthesized by a modified transmetallation route between Tl{C5H2[Si(CH3)(3)](3)} and europium powder in toluene. 1 crystallizes in the monoclinic space group C2/c (No. 15) with a = 20.293(5) angstrom, b = 20.221(5) angstrom, c = 9.654(2) angstrom, beta = 106.412(5)degrees, V = 3800.1(15)angstrom(3), Z = 4. The unit cell contains monomeric molecules that adopt a bent metallocene conformation with two partially staggered Cp''' ligands. Magnetic susceptibility measurements in the temperature range 2-300 K display ideal Curie paramagnetic behaviour of the 4171 system with Curie constant C = 9.6 x 10(-5) m(3) K mol(-1) corresponding to temperature independent mu(eff) = 7.8.