Synthesis, characterization and crystal structures of bismuth(III) complexes with triethylenetetraaminehexaacetic acid and trans-cyclohexane-1,2-diaminetetraacetic acid

Abstract

Two new water-soluble bismuth(III) complexes with polyaminocarboxylate ligands have been prepared, characterized by IR spectroscopy and crystal-structure analysis. The complex with triethylenetetraaminehexaacetic acid (H₆ttha) has the stoichiometry Bi(H₃ttha)·3H₂O 1. It crystallizes in the space group P2/c with two independent ½(H₃ttha·Bi) units in which the cations are located on the crystallographic two-fold axis. It is the first example of a polyaminocarboxylate complex of Bi^III displaying a co-ordination number of ten, through four nitrogen atoms and six oxygens belonging to the acetates. The ligand is wrapped round the cation in a bicapped square-antiprismatic geometry. In the complex with trans-cyclohexane-1,2-diaminetetraacetic acid (H₄cydta), Bi(Hcydta)·5H₂O 2, the co-ordination number is eight with a square-antiprismatic geometry around the Bi. For each Bi atom two of the co-ordinated oxygen atoms belong to neighbouring molecules; these bridging oxygen atoms are different in the two subunits and connect the complexed entities in a polymeric network.