Menthyl-Functionalized Chiral Nonracemic Bis(indenyl) Complexes of Zirconium, Iron, Nickel, and Ruthenium

Optically active complexes of Zr, Fe, Ni, and Ru containing the chiral, menthyl-substituted indenyl ligands (−)-3-menthyl-4,7-dimethylindene and (−)-2-menthylindene are described. Metathetic reaction of the chiral main-group-metal salts of these indenyl systems with the appropriate starting materials of Zr, Fe, and Ni yielded the complexes ( pR )( pR )-/( pR )( pS )-(1-menthyl-4,7-dimethylindenyl) 2 ZrCl 2 ( 4a / 4b ), ( pR )-/( pS )-(cyclopentadienyl)(1-menthyl-4,7-dimethylindenyl)ZrCl 2 ( 5a / 5b ), ( pR )( pR )-/( pR )( pS )-/( pS )( pS )-(1-menthyl-4,7-dimethylindenyl) 2 Fe ( 6a / 6b / 6c ), ( pR )( pR )-/( pR )( pS )-/( pS )( pS )-(1-menthyl-4,7-dimethylindenyl) 2 Ni ( 7a / 7b / 7c ), (+)-(2-menthylindenyl) 2 Fe ( 8 ), and (−)-(2-menthylindenyl) 2 Ni ( 9 ). Ru(acac) 3 reacts with (−)-(2-menthylindenyl)lithium ( 3 ), yielding (−)-(2-menthylindenyl) 2 Ru ( 10 ). Depending on the reaction conditions, compounds 4 − 7 were formed as mixtures of diastereomers with respect to the planar chirality of the indenyl ring system. The apparent diasteromeric excess varied between 13 and 50% de. The Fe, Ni, and Ru complexes were purified by chromatography via dried alumina under nitrogen. The structures of 4b and 8 were determined by single-crystal X-ray diffractometry.