I 11 Under these experimental conditions. UV spectroscopic investigations [lo] have revealed that I and 2 are present as solvent-separated ion pairs. The NMR chemical shifts of 1 and 2 (Table ) largely correspond to those of simple fluorenyllithium systems . The differences in the 6 H and 6C values observed for 1 and 2 provide no evidence of an interaction between the fluorenyl moieties. 1121 Crystal structure analyses of 1 and 2 : Enraf-NoniusCAD4 diffractometer, Cu,, radiation, i = 1.5405 A, graphite monochromator. The structures were solved by direct methods (DIRDIF). Empirical absorption correction, anisotropic temperature factors for 0, C, Li, refinement of the H atoms in the "riding mode" with fixed isotropic temperature factors. 1: T = 120 K, triclinic, space group Pi, u = 17.350(2), h = 10.091 (6). c = 17.870(1)A, I = 104.91 (5). , 8 = 66.24(6), 9 = 105.33( )", V = 2721 A3, Z = 2. pEalcd = 1.16 g ~m -~. ~(CU,,) = 5.477cm-I. 5984 reflections, of which 3564 were observed [I > 3 o ( I ) ] . R = 0.068, R, = 0.065. 2: T = 150 K. triclinic. space group Pi, u = 18.610(3), b = 18.836(3), c = 9.751 ( I ) & a = 100.07(1), 1 = 104.52(1). 7 = 63.12(2);. V = 2942 A3, 2 = 2, pca,cd = 1.13 gcm-', ~(CU,,) = 5.274 cm-'. 4879 reflections, of which 3235 were observed [I > 3 cr (I)]. R = 0.094, R, = 0.096.