New Schiff bases derived from trans-pyrazolylcyclohexanol: synthesis, co-ordination chemistry and structural features

Abstract

Transformation of the OH function of trans-2-(pyrazol-1-yl)cyclohexan-1-ol into an amino group was achieved by various methods with inversion of the reaction centre and provided access to new polydentate Schiff bases bearing phenol, pyridine and furan donors. The co-ordination chemistry of these bases was investigated for Pd ^II , Re ^I and Re ^V . It was shown by means of NMR spectroscopy that the special stereochemical situation of the 1,2-cis-configurated cyclohexane backbone allows a flexible adaptation to different co-ordination conditions. On the other hand, the rigid asymmetrically substituted cyclohexane ring is responsible for an asymmetric arrangement of the donor fragments at the metal centre, which is required for applications of these compounds in enantioselective catalysis.