[1]FERROCENOPHANES CONTAINING A GROUP-4 TRANSITION-METAL IN THE BRIDGE - X-RAY STRUCTURE OF ONE REPRESENTATIVE

New [1]ferrocenophanes (RC5H4)2ML2 (1) (R = H, t-Bu; L2 = (C5H4)2Fe; M = Ti, Zr, Hf) containing a transition metal in the “phane” bridge have been obtained when the 1,1’-dilithioferrocene-TMEDA complex was reacted with metallocene dichloride at room temperature. Compounds 1 exposed to air led to µ-oxo complexes [(C5H5)ML5]2O (L’= (C5H5)(C5H4)Fe). Spectroscopically speaking, the ferrocene part of the molecules is the most affected by structural strains and by the bridging metal electronegativity. The molecular structure of [(H3C)3CC5H4]2Zr(C5H4)2Fe has been determined by a single-crystal X-ray diffraction study. The crystal was found to be monoclinic, C2/c, with a = 18.715 (2) Å, b = 9.691 (1) Å, c = 14.923 (2) Å, μ = 122.47 (1)°, V = 2283 (1) Å3, and Z = 4. The structure was refined to R = 0.026 and Rw = 0.029 with use of 2685 unique reflections with I ⩾ 3s(I) recorded at room temperature. The Zr-Fe distance equal to 2.9621 (5) Å might suggest the occurrence of a weak dative bond between electron-rich and electron-poor metal centers. © 1990, American Chemical Society. All rights reserved.