Studies of V(III) complexes with selected α-N-heterocyclic carboxylato NO donor ligands: structure of a new seven-coordinated pentagonal bipyramidal complex containing picolinato ligands

Some highly stable V(III) complexes involving the biologically important and chemically interesting ONO donor ligand pyridine-2,6-dicarboxylic acid (dipicolinic acid, DPAH2) are reported. They include both homo- and hetero-chelates involving DPAH2 and some other bidentate chelating ligands and one of them is a new highly stable seven- coordinated mononuclear V(III) complex, [V(DPA)(PA)(H2O)2]·H2O 4 (PA = picolinate anion). The complex 4 containing two different α-N-heterocyclic carboxylates has a pentagonal bipyramidal structure with the equatorial plane accommodating the ONO and NO donor points while the two water molecules occupy the axial positions.