Conformational preferences of titanocene dichlorides with ligands derived from menthol: Comparison of structures in solution and in the crystal

A comparison of the structures of three titanocenes, 1, 2, and 3, with liga nds derived from menthol in the solid state and in solution determined by X -ray crystallography and by modern NMR methods has been carried out. The re spective structures are essentially the same in solution and in the crystal . It seems that an examination of this type has not appeared in the literat ure as yet. Complexes 1 and 2 are conformationally fixed by interactions of the cyclopentadienyl ring with the menthol substitutents. This remote effe ct has to the best of our knowledge not been observed before and leads to e fficient chirality transfer to the distant part of the chiral pockets. The results are of relevance for catalyst design in metallocene-catalyzed react ions and for structure determination of similar metallocenes both in the so lid state and in solution.