Stereoselective synthesis of chiral pinene[5,6]bipyridine ligands and their coordination chemistry.
The C(2)-symmetric chiral pinene[5,6]bipyridine V (Chart 1) was synthesized according to a procedure published by our group recently (Kolp, B.; Abeln, D.; Stoeckli-Evans, H.; Zelewsky, A. v. Eur. J. Inorg. Chem. 2001, 1207). A series of stereoselectively alkylated derivatives (Va-Vo) (Table 1) was prepared. The solid-state structures of the compounds Vc and Vk were determined by single-crystal X-ray diffraction, where both compounds show a transoid conformation of the bipyridine unit and proved to be alkylated stereoselectively from the sterically less hindered side of the pinene moiety. The X-ray structure of the cobalt complex 4 shows the metal ion to be tetrahedrally coordinated by one chiral bipyridine V and two chloride ligands. If 2 equiv of ligand V was used, 2:1 complexes were obtained with Cu(I), Ag(I), and Co(II) ions.
Lötscher
D
D
Department of Chemistry, University of Fribourg, Pérolles, CH-1700 Fribourg, Switzerland.
Rupprecht
S
S
Collomb
P
P
Belser
P
P
Viebrock
H
H
von Zelewsky
A
A
Burger
P
P