1) Coordination compound 
Diimines are organic compounds containing two imine (RCH=NR`) groups. The most popular derivatives are 1,2-diketones and 1,3-diimines. These compounds are used as ligands and as precursors to heterocycles. Diimines are prepared by condensation reactions: the dialdehydes or diketones is treated with an imine and water is eliminated. Similar method....