Weak absolute helicity direction in Ni-salen by trans-cyclohexane-(1R,2R)-diamine

Helical Ni-salen foldamers were synthesized from enantiomerically pure cyclohexane-(1R,2R)-diamine, N, N'-bis-(N-phenyl (4-diphenylphosphine)-3-salicylidenato carboxamide)-(1R,2R)-cyclohexanediamina-to-nickel(II). X-ray structural characterization of the absolute helicities observed confirms our earlier assertions, based on solution spectroscopic evidence, that trans-cyclohexane-diamine, a common component of chiral salen catalysts, is a weak director of absolute helicity for Ni-salen. (C) 2010 Elsevier B. V. All rights reserved.