Chiral Bis(η5,η1-Pentafulvene) Titanium Complexes
M. Diekmann, G. Bockstiegel, A. Lützen, M. Friedemann, D. Haase, W. Saak, R. Beckhaus
Organometallics 2006, 25(2), 339-348.
The series of bis(pentafulvene)titanium complexes (h6-C5H4:CR2)2Ti (:CR2 = C(p-tol)2 (3), adamantyl (4)) and their corresponding bis(benzofulvene) derivs. (h6-C9H6:CR2)2Ti (:CR2 = C(p-tol)2 (7), adamantyl (8)) have been synthesized by reaction of TiCl3×3THF with the pentafulvene ligands (2 equiv.) and magnesium as reducing agent (1.5 equiv.). The bis(fulvene) complexes 7 and 8 have been obtained as diastereomerically pure compds. All complexes have been characterized by spectroscopy and by single-crystal x-ray diffraction. The bonding situation is best described as a p-h5:s-h1 coordination mode. The bis(fulvene) complex 3 is approx. C2 sym., whereas 7 crystallizes as a conglomerate in the monoclinic space group P21 and one of the enantiomers was identified as a (S,pS,pR) stereoisomer showing C1 symmetry. The adamantyl benzofulvene complex 8 crystallizes in the monoclinic space group P21/c; both benzofulvene ligands are coordinated as optical antipodes, and a (S,pS,pR)/(R,pR,pS) configuration is found in the solid state. Reaction of 3 and 7 with HCl/Et2O leads to the corresponding bis(cyclopentadienyl)titanium chlorides (h5-C5H4-CHR2)2TiCl2 (R = p-tol) and the bis(indenyltitanium) deriv. (h5-C9H6-CHR2)2TiCl2 (R = p-tol2).