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We prepared the 2-hydroxy-5-trimethylsilylferrocenecarbaldiminesystems 13enantioselectively by a short synthetic routestarting from the chiral ferrocene carbaldehyde acetal 5. The imines 13a–cwere used to synthesize thezwitterionic (“ferrocene-salaldiminato”)2ZrCl4complexes 14a–c. Activation with MAO gave homogeneous Ziegler–Natta catalysts,which showed only a moderate ethylene polymerization activity, similarto the unsubstituted parent “ferrocene-salaldiminato”zirconium systems. Consequently, a synthetic route was devised andcarried out to make the corresponding 2-hydroxy-3,5-bis(trimethylsilyl)ferrocenecarbaldimines(21) available. The enantiomerically highly enrichedligands (pS)-21aand-dderived from the aldehyde and aniline or cyclohexylamine,respectively, were used to synthesize the corresponding (“ferrocene-salaldiminato”)2ZrCl4complexes 22a,d. Both gave highly active homogeneous Ziegler–Natta catalystsupon activation with MAO for the formation of linear low molecularweight polyethylene. Complex 22dand many ligand precusorsfrom both sequences were characterized by X-ray diffraction. [ABSTRACT FROM AUTHOR]

The chromium-templated benzannulation of the chromium cymanthrene-type carbene 3with 3-hexyne affords the heterobimetallic chromium−manganese hydroquinoid dibenzo[c,e]indene complexes anti-4and syn-5, in which the chromium entities are coordinated regioselectively to the hydroquinoid ring. Both diastereomers undergo a thermoinduced haptotropic migration of the chromium moiety to give their haptotropomers anti-6and syn-7in comparable yields, independent of the relative configuration of both metal centers, while the manganese fragment remains coordinated to the cyclopentadienyl ring. The molecular structures of all heterobimetallic complex structures were established by X-ray analysis. A kinetic NMR study of the chromium migration revealed first-order kinetics for the anticomplex 4, supporting the intramolecular nature of the metal rearrangement. [ABSTRACT FROM AUTHOR]