The tetrakis(triphenylphosphine)palladium-catalyzed cross coupling of 2-bromoindene or 2-bromo-4,7-dimethylindene with menthylmagnesium chloride gave the novel ligands 2-menthylindene (10) and 2-menthyl-4,7-dimethylindene (11) in 66 and 57% yields. These indenes were deprotonated with n-BuLi to give isolated indenyllithium complexes which were metalated with zirconium tetrachloride to give bis(2-menthylindenyl)zirconium dichloride ( 14) and bis(2-menthyl-4,7-dimethylindenyl)zirconium dichloride (15) in 40 and 66% yields. Both complexes formed as their single possible stereoisomer and were characterized by X-ray crystallography and MS, NMR, and IR spectroscopy. The variable-temperature 1 H NMR spectrum of bis(2-menthyl-4,7-dimethylindenyl)zirconium dichloride (15) showed that it interconverts with a rotational activation barrier of about 12.5 ( 0.5 kcal/mol, and that a 60:40 mixture of C 2 -symmetric diastereomeric conformations was present at -50 °C. The 1 H NMR spectrum of bis(2-menthylindenyl)zirconium dichloride ( 14) was invariant between -50 and +50 °C. Complexes 14 and 15 polymerized propene in the presence of methylaluminumoxane (MAO) and hydrogen (10 960 and 33 750 g PP/g Zr h, respectively). The molecular weights and stereoregularity of the polymers produced were low.

Optically active complexes of Rh, Ir, Co, and Mo containing the chiral, menthyl-substituted indenyl ligands (-)-3-menthyl-4,7-dimethylindene, (-)-4,7-diisopropyl-3-menthylindene, and (+)-3-neomenthylindene are described. Metathetic reaction of the chiral main group metal salts of these indenyl systems with the appropriate starting materials of Rh and Ir yielded the complexes (-), formed by transmetalation of Mo(CO) 6 , is oxidized by I 2 , yielding (pR)/ (pS)-(1-menthyl-4,7-dimethylindenyl)Mo(CO) 3 I (17a/b). Depending on the reaction conditions, all compounds were formed as mixtures of diastereomers with respect to the planar chirality of the indenyl ring system. The diasteromeric excess varied between 9% and 71% de. Diastereomerically pure compounds were obtained after chromatography by dried alumina under nitrogen. The structures of 7a, 7b, 9a, 9b, and 14a were determined by single-crystal X-ray diffractometry.

Optically active complexes of Rh, Ir, Co, and Mo containing the chiral, menthyl-substituted indenyl ligands (−)-2-menthylindene and (−)-2-menthyl-4,7-dimethylindene are described. Metathetic reaction of the chiral lithium salts of these indenyl systems (1, 2) with the appropriate starting materials of Rh and Ir yielded the complexes (−)-(2-menthylindenyl)Rh(COD) (3), (−)-(2-menthyl-4,7-dimethylindenyl)Rh(COD) (4), (−)-(2-menthylindenyl)Rh(C2H4)2 (5), (−)-(2-menthyl-4,7-dimethylindenyl)Rh(C2H4)2 (6), (−)-(2-menthylindenyl)Ir(COD) (7), (−)-(2-menthylindenyl)Ir(C2H4)2 (8), (−)-(2-menthyl-4,7-dimethylindenyl)Ir(C2H4)2 (9), and (−)-(2-menthyl-4,7-dimethylindenyl)Ir(COE)2 (10). Co2(CO)8 and CoCl2(dppe) react with (−)-2-menthylindenyllithium (1) yielding (−)-(2-menthylindenyl)Co(CO)2 (11) and (+)-(2-menthylindenyl)Co(dppe) (12). (−)-Li[(2-menthylindenyl)Mo(CO)3](THF)2 (13), formed by transmetalation of Mo(CO)6, is oxidized by I2, yielding (−)-(2-menthylindenyl)Mo(CO)3I (14), or by allylic chloride, yielding (allyl)(2-menthylindenyl)Mo(CO)2 (15). All compounds were formed stereomerically pure and were obtained after chromatography by dried alumina under nitrogen. The structures of 3, 4, 6, 7, and 14 were determined by single-crystal X-ray diffractometry. Variable temperature 1H NMR spectra of 5, 6, 8, and 9 were recorded to determine the energy barriers for rotation of ethylene along the metal−indenyl and metal−ethylene axes.