Novel Co complexes containing fluorescent coumarin-N-acylhydrazone hybrid ligands: Synthesis, crystal structures, solution studies and DFT calculations.

A series of new Co complexes of the type [Co(dien)(L1-L3)]ClO (1-3), containing fluorescent coumarin-N-acylhydrazonate hybrid ligands, (E)-N'-(1-(7-oxido-2-oxo-2H-chromen-3-yl)ethylidene)-4-R-benzohydrazonate [where R=H (L1), OCH (L2) or Cl (L3)], were obtained and isolated in the low spin Co configuration. Single-crystal X-ray diffraction showed that the coumarin-N-acylhydrazones act as tridentate ligands in their deprotonated form (L). The cation (+1) complexes contain a diethylenetriamine (dien) as auxiliary ligand and their structures were calculated by DFT studies which were also performed for the Co (S=1/2 and S=3/2) configurations.