New benzyl complexes of the lanthanides. Synthesis and crystal structures of [(C(5)Me(5))(2)Y(CH2C6H5)(thf)], [(C(5)Me(5))(2)Sm(CH2C6H5)(2)K(thf)(2)](infinity), and [(C(5)Me(5))Gd(CH2C6H5)(2)(thf)]

YBr3 reacts with potassium benzyl and [K(C(5)Me(5))] in THF to give KBr and the monobenzyl compound [(C(5)Me(5))(2) . Y(CH2C6H5)(thf)] 1. The analogous reaction with SmBr3 in THF leads to the polymeric product [(C(5)Me(5))(2)Sm(CH2C6H5)(2) . K(thf)(2)](infinity) 2, with GdBr3 to [(C(5)Me(5))Gd(CH2C6H5)(2)(thf)] 3. The structures of 1-3 were determined by X-ray single crystal structure analysis: 1: Space group <P(1)over bar>, Z = 2, a = 851.2(4) pm, b = 952.7(4) pm, = 1858.6(8) pm, alpha = 79.90(4)degrees, beta = 77.35(4)degrees, gamma = 73.30(3)degrees. 2: Space group <P(1)over bar>, Z = 2, a = 903.3(2) pm, b = 1375.9(3) pm, c = 1801.1(4) pm, alpha = 100.92(3)degrees, beta = 100.77 degrees, gamma = 98.25(3)degrees. 3: Space group P2(1)/n(1) Z = 8, a = 1458.2(5) pm, b = 927.8(3) pm, c = 3792.9(15) pm, beta = 96.83(3)degrees.