Chiral Bis(η51-pentafulvene)titanium Complexes

The series of bis(pentafulvene)titanium complexes (η6-C5H4CR2)2Ti (CR2 = C(p-tol)2 (3), adamantyl (4)) and their corresponding bis(benzofulvene) derivatives (η6-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 compounds. All complexes have been characterized by spectroscopy and by single-crystal X-ray diffraction. The bonding situation is best described as a π-η5:σ-η1 coordination mode. The bis(fulvene) complex 3 is approximately C2 symmetric, 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 (η5-C5H4−CHR2)2TiCl2 (R = p-tol (9)) and the bis(indenyltitanium) derivative (η5-C9H6−CHR2)2TiCl2 (R = p-tol2 (10)).