Chiral bis(η5:η1-pentafulvene)titanium complexes

The series of bis(pentafulvene)titanium complexes (eta(6)-C5H4=CR2)(2)Ti (=CR2 = C(p-tol)(2) (3), adamantyl (4)) and their corresponding bis(benzofulvene) derivatives (eta(6)-C9H6=CR2)(2)Ti (=CR2 = C(p-tol)(2) (7), adamantyl (8)) have been synthesized by reaction of TiCl3 center dot 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 compounds. All complexes have been characterized by spectroscopy and by single-crystal X-ray diffraction. The bonding situation is best described as pi-eta(5):sigma-eta(1) coordination mode. The bis(fulvene) complex 3 is approximately C, symmetric, whereas 7 crystallizes as a conglomerate in the monoclinic space group P2(1) and one of the enantiomers was identified as a (S,pS,pR) stereoisomer showing C, symmetry. The adamantyl benzofulvene complex 8 crystallizes in the monoclinic space group P2(1)/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 (eta(5)-C5H4-CHR2)(2)TiCl2, (R = p-tol (9)) and the bis(indenyltitanium) derivative (eta(5)-C9H6-CHR2)(2)TiCl2 (R = p-tol(2) (10)).