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The enantioselective synthesis of a novel-type C(3)-symmetric tripodal ligand that is composed of a central mesitylene-derived core and three functionalized, axially chiral biaryl subunits is described. The triol (M,M,M)-3 is a suitable catalyst for the enantioselective addition of dialkylzinc to various aromatic aldehydes with asymmetric inductions of up to 98% ee.

The Ðrst half sandwich cyclopentadienyl complexes 2È5 with a carbene complex subtituent at the cyclopentadienyl ring are presented. These complexes deserve interest because one metal atom (Cr, Mo, W, Fe) is incorporated in the p system of the ligand in conjugation to the cyclopentadienyl ring complexed to iron. In addition to intermetallic interactions these complexes o †er the possibility of reactions at both metal atoms. An X-ray structure analysis of 2 reveals, however, that the carbeneÈchromium p bond is not perfectly coplanar with the cyclopentadienyl ring. Cyclic voltammetry of some of the complexes prepared shows a decrease in oxidation potential upon carbene complex substitution at the cyclopentadienyl ring for 2 and 7 by 118 and 63 mV, respectively. A ligand exchange reaction with bis(diphenylphosphino)ethane (dppe) under irradiation results in the incorporation of two dppe molecules.