SYNTHESIS, STRUCTURE AND PROPERTIES OF DIVALENT BIS(DI-TERT-BUTYLCYCLOPENTADIENYL)YTTERBIUM COMPLEXES WITH DIETHYL-ETHER AND 1,2-DIMETHOXYETHANE

The reaction between YbI2 and 1,3-(Bu2C5H3Na)-Bu-t containing some 1,2 -(Bu2C5H3Na)-Bu-t in diethyl ether or 1,2-dimethoxyethane afforded (1, 3-(Bu2C5H3)-Bu-t)(2)Yb . OEt2, (1), (1,3-(Bu2C5H3)-Bu-t)(2)Yb . DME (2 ) and (1,2-(Bu2C5H3)-Bu-t)(2)Yb . DME (2a). The crystal structures of 1 and 2a were determined. Crystals of 1 are monoclinic: a = 11.302(2) Angstrom, b = 19.018(4) Angstrom, c = 14.404(3) Angstrom, beta = 90.41 (3)degrees, d(calc), = 1.291 g cm(-3), space group P2(1)/n, z = 4. Mea n bond distances Yb-C, Yb-O and the bond angle Cp-Yb-Cp are 2.69(2) An gstrom, 2.430(14) Angstrom, and 133.0 degrees, respectively. Crystals of 2a are monoclinic: a = 13.782(3) Angstrom, b = 10.299(2) Angstrom, c = 10.849(2) Angstrom, beta = 95.04(3)degrees, d(calc) = 1.337 g cm(- 3), space group C2, z = 2. Mean bond distances Yb-C, Yb-O and the bond angle Cp-Yb-Cp are 2.72(2) Angstrom, 2.53(2) Angstrom, and 143.2 degr ees, respectively. The ether-free complex (1,3-(Bu2C5H3)-Bu-t)(2)Yb (3 ) displays low catalytic activity in the polymerization of ethene. (C) 1998 Elsevier Science S.A. All rights reserved.