Asymmetric catalyses. Part 19. X-ray structure analysis of RNiCl2 and R2Ni, R=trans-2.3-bis(diphenylphosphino)-bicyclo[2.2.1] heptane

Renorphos, trans-2,3-bis(diphenylphosphino)bicyclo [2.2.1] heptane, has been used as a ligand to prepare the complexes (renorphos)NiCl2, I, and (renorphos)2Ni, II. X-ray structure analyses of which have been carried out. For square-planar I there is an optional self-resolution on crystallization, whereas the crystal of tetrahedral II consists of pairs of enantiomers, whose components contain identical renorphos ligands. Two of the four phenyl rings of each renorphos ligand, responsible for the chirality transmission in asymmetric catalysis, are of the equatorial and axial type respectively. For the orientation of the phenyl planes a new measure, the setting angle, is proposed.