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

• Published in: Organometallics 2001-05, Vol.20 (10), p.1983-1991
• Main Authors: Schumann, Herbert, Stenzel, Oleg, Dechert, Sebastian, Halterman, Ronald L
• Format: Article
• Language: English
• ISSN: 0276-7333; 1520-6041
• DOI: 10.1021/om001084n

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)2ZrCl2 (4a/4b), (pR)-/(pS)-(cyclopentadienyl)(1-menthyl-4,7-dimethylindenyl)ZrCl2 (5a/5b), (pR)(pR)-/(pR)(pS)-/(pS)(pS)-(1-menthyl-4,7-dimethylindenyl)2Fe (6a/6b/6c), (pR)(pR)-/(pR)(pS)-/(pS)(pS)-(1-menthyl-4,7-dimethylindenyl)2Ni (7a/7b/7c), (+)-(2-menthylindenyl)2Fe (8), and (−)-(2-menthylindenyl)2Ni (9). Ru(acac)3 reacts with (−)-(2-menthylindenyl)lithium (3), yielding (−)-(2-menthylindenyl)2Ru (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.