ORGANONICKEL(II) COMPLEXES CONTAINING ARYL LIGANDS WITH CHIRAL PYRROLIDINYL RING-SYSTEMS - SYNTHESES AND USE AS HOMOGENEOUS CATALYSTS FOR THE KHARASCH ADDITION-REACTION

New chiral organonickel(II) complexes 3a-d have been synthesized conta ining monoanionic terdentate ligands of the type 2,6-bis[(1-pyrrolidin yl)methyl]phenyl. Chirality is [GRAPHICS] introduced at the nitrogen d onor atoms, which are part of the pyrrolidinyl ring systems, by placin g substituents on the 2 or 5 positions of the rings. The complexes hav e been characterized variously by H-1- and C-13-NMR spectroscopy, UV/V is spectroscopy and X-ray crystallography. Crystals of 3b are monoclin ic, space group P2(1), with a = 11.572(2), b = 11.804(2), c = 13.249(3 ) beta = 107.00(2)-degrees, Z = 4, final R = 0.043 for 3043 observed r eflections. Crystals of 3c are tetragonal, space group P4(1)2(1)2(1), with a = b = 12.2957(14) angstrom, c = 26.418(3) angstrom, Z = 8, fina l R = 0.052 for 1479 observed reflections. Crystals of 3d are tetragon al, space group P4(1)2(1)2, with a = b = 11.0869(5), c = 21.718(2) ang strom, Z = 4, final R = 0.046 for 1469 observed reflections. The catal ytic ability of the nickel complexes in the addition reaction of polyh alogenated compounds with alkenes (Kharasch addition) is markedly infl uenced by the geometry around the nickel atom and only 3a and 3b prove to be effective catalysts. The highest enantiomeric excesses of 16-17 % obtained with 3b and L-menthyl methacrylate in this catalytic reacti on indicate that the C2 chiral fence produced by the Me-substituted py rrolidinyl rings is not very effective for the transfer of chiral info rmation.