REACTIONS OF LANTHANIDE HALIDES WITH ALKALIBENZYL COMPOUNDS - SYNTHESIS AND CRYSTAL-STRUCTURES OF [(TMEDA)(C6H5CH2)(2)Y(MU-BR)(2)LI(TMEDA)], [(TMEDA)(2)SMBR(MU-BR)(2)LI(TMEDA)] AND [(DME)(2)SMBR(MU-BR)](2)

Alkali-benzyl compounds react via a metathesis reaction with lanthanid e halides to benzyl complexes of the rare earths. Reaction of [(C6H5CH 2)Li(tmeda)] with YBr3 leads to the complex [(tmeda)Y(C6H5CH2)(2)(mu-B r)(2)Li(tmeda)] 1, in which Yttrium and lithium are linked via two bro mide bridges. However, the reaction of [(C6H5CH2)Li(tmeda)] with SmBr3 in toluene/tmeda leads under reduction of the Sm ion to the compound [(tmeda)(2)SmBr(mu-Br)(2)Li(tmeda)] 2. 2 reacts with DME to yield the dimeric compound [(dme)(2)SmBr(mu-Br)](2) 3. The structures of 1-3 wer e determined by X-ray single crystal structure analysis: 1: Space grou p P2(1)/c, Z = 4, a = 829.5(6) pm, b = 1477.9(11) pm, c = 2575.0(10) p m, beta = 92.03(6)degrees, 2: Space group P2(1), Z = 2, a = 954.7(3) p m, b = 1338.5(6) pm, c = 1244.9(5) pm, beta = 107.51(3)degrees, 3: Spa ce group P (1) over bar, Z = 1, a = 797.2(7) pm, b = 515.3(7) pm,c = 1 169.7(5) pm, alpha = 100.96(6)degrees, beta = 92.03(6)degrees, gamma = 91.75(7)degrees.