Easy Synthesis of New Chiral Tetradentate N 4 Schiff Bases and Their Use as Ligands for Metal Complexes

The chiral N 4 Schiff bases (1 R, 2 R )‐ N , N ′‐bis(2‐ p ‐tosylaminobenzylidene)‐1,2‐diaminocyclohexane (H 2 CyTs, 1 ), (1 R, 2 R ) N , N ′‐bis(2‐trifluoromethylsulfonaminobenzylidene)‐1,2‐diaminocyclohexane (H 2 CyTf, 2 ), (1 R, 2 R )‐ N , N ′‐bis(2‐aminobenzylidene)‐1,2‐diaminocyclohexane ( 3 ) and (1 R, 2 R )‐ N , N ′‐bis(2‐nitrobenzylidene)‐1,2‐diaminocyclohexane ( 4 ) were synthesized by a new and easy method in high purity and good yields. All the organic compounds were characterized by elemental analysis, mass spectrometry, IR and 1 H and 13 C NMR spectroscopy. Divalent Co, Cu and Ni complexes 5−8 , containing the sulfonamide ligands 1 or 2 , have been prepared and characterized. The X‐ray crystal structures of complexes [Co(1 R, 2 R )‐CyTs] ( 6 ) and [Ni(1 R, 2 R )‐CyTf] ( 8 ) have been solved. These complexes are potential precursors for homogeneous asymmetric catalysis of a variety of reactions. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)